**The Role of Weed and Cover Crops on Soil and Water Conservation in a Tropical Region**

Cezar Francisco Araujo-Junior, Bruno Henrique Martins, Vinicius Yugi Higashi and Carlos Alberto Hamanaka

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/59952

#### **1. Introduction**

Weed control is one of the most intensive management practices in different production systems in tropical regions and can influence both agricultural productivity and impact the environment. Despite the importance of this issue, studies reporting the action of different methods of weed control on soil physical properties and their effects on the management and conservation of soil and water are scarce, requiring a greater understanding of the adequacy of management systems. Weeds are considered one of the major constraints in crop production and may substantially reduce yields when not controlled properly. Potential yield reductions caused by uncontrolled weeds are estimated at 45 % to 95 % depending on the crop, ecological and climatic conditions [1].

A key to effectiveness weed management is a holistic approach regarding the scenario considered and must include a combination of tactics and practices in order to successfully and economically reduce the potentially negative impacts inherent to weeds incidence [2]. There are numerous methods of mechanical control of weeds including mowing, cultivation, hoeing, flaming, mulching, and hand weeding. Chemical control of weeds mainly consists of using pre and post-emergence herbicides and soil fumigants [2]. Herbicides and tillage are the dominant practices in many production systems due to efficiency and facilities for weed control [3]. However, these methods may be inadequate for weed control in tropical conditions and may have negative impacts on soil and to the environment most of these impacts are related to hydric erosion [4-7] and soil compaction, which affect soil quality [8-11]. Weed management and cover crops also affects micropedological [6], biological [12-13], chemical soil properties [12, 14-17].

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Given the complexity and limitations inherent to each of these methods, integrated weed management systems is an alternative to traditional methods and can be useful for soil and water conservation in Tropical conditions. One of the goals of the integrated weed manage‐ ment systems is to develop methods that provide better use of resources. In addition, to optimize crop production and growth yield through the concerted use of preventive tactics, scientific knowledge, management skills, monitoring procedures, and efficient use of control practices [1]. It is known that, weed control and cover crops management has several impact on soil properties and effects soil and water conservation due changes on soil structure in the row and interrow crop.

The alternative weed control in a newly developed orchard through three years with mowing in Spring, Summer and Fall and tillage in winter improved soil biological and fertility properties compared to conventional weed control methods (chemical and tillage control) [12]. The authors observed that this alternative weed control method improved microbial biomass carbon, phosphorus-solubilizing microbial activity, mycorrhizal fungal spores numbers and soil organic matter.

At Analândia, State of São Paulo, Brazil in a coffee plantation, the constant use of the mechan‐ ical mower between coffee rows caused reduction in the coffee plants yield due to weed infestation. However, at Autumn / Winter seasons, when weed management is performed by herbicide applications, such effect is not observed. [5]. Soil compaction is the main ongoing degradation process and concerns in mechanical weed control. Soils under weed control with rotary shredder may experience detrimental effects, such as increased soil strength, measured by a portable recording penetrometer [8], and soil load bearing capacity [18].

Integrated weed management systems and cover crops used as a green manure can be useful in Tropical region, since it may protect soil against degradation processes, such as compaction and erosion. The integrated weed management systems consists in selection and use of the different weed control based on cost-benefit analysis, taking into account the benefits to the production system and the environment as important strategies in Conservation Agriculture.

Conservation Agriculture (CA) involves three basic practices: (i) significant reduction of soil tillage and disturbance, (ii) permanent, or at least semi-permanent, soil protection by using crop residues or selected cover crops, and (iii) diversification of crop rotations and intercropping [19]. CA practices often enhance and utilize soil and crop microenviron‐ ments to inhibit germination, growth, and spread of weeds while minimizing the use of synthetic herbicides. Examples of conservation tillage that may fit into a weed manage‐ ment control/suppression program include reduced tillage, cover crops, crop rotation, variable row spacing, and timing of crop planting [20].

Cover crops and cropping residues used in Conservation Agriculture systems serve as a protection for the soil surface against weather aggressions and water erosion, to maintain soil moisture, to suppress weed growth and to provide shelter and food for the soil biota [21]. Also, under Conservation Agriculture regime, the use of crop rotations or intercropping is consid‐ ered essential, as it offers an option for pest/ weed management that is no longer realized through soil tillage [22].

In perennial crops (such as coffee and apples), cover crops species and weed between rows of the crops may be helpful on nutrient cycling. Results from six trials conducted in Inceptisol and Oxisol by Chaves et al. [17] denoted that the total amount of plant nutrient accumulated in the above ground dry matter varied from 31 to over 400 kg ha-1 of nitrogen, from 20.6 to more 273 kg ha-1 of calcium, from 4 to over 40 kg ha-1 of magnesium, from 22 to over 224 kg ha-1 of potassium, and from 2.2 to over 26 kg ha-1 for phosphorus. In addition, the plant residues were found to decrease soil acidity [17]. The authors concluded that in Tropical conditions, cover crops are recommended as an important management strategy for coffee and apple production because they provide large quantities of dry matter and plant nutrients to improve soil fertility of the degraded acid soils.

Given the complexity and limitations inherent to each of these methods, integrated weed management systems is an alternative to traditional methods and can be useful for soil and water conservation in Tropical conditions. One of the goals of the integrated weed manage‐ ment systems is to develop methods that provide better use of resources. In addition, to optimize crop production and growth yield through the concerted use of preventive tactics, scientific knowledge, management skills, monitoring procedures, and efficient use of control practices [1]. It is known that, weed control and cover crops management has several impact on soil properties and effects soil and water conservation due changes on soil structure in the

The alternative weed control in a newly developed orchard through three years with mowing in Spring, Summer and Fall and tillage in winter improved soil biological and fertility properties compared to conventional weed control methods (chemical and tillage control) [12]. The authors observed that this alternative weed control method improved microbial biomass carbon, phosphorus-solubilizing microbial activity, mycorrhizal fungal spores numbers and

At Analândia, State of São Paulo, Brazil in a coffee plantation, the constant use of the mechan‐ ical mower between coffee rows caused reduction in the coffee plants yield due to weed infestation. However, at Autumn / Winter seasons, when weed management is performed by herbicide applications, such effect is not observed. [5]. Soil compaction is the main ongoing degradation process and concerns in mechanical weed control. Soils under weed control with rotary shredder may experience detrimental effects, such as increased soil strength, measured

Integrated weed management systems and cover crops used as a green manure can be useful in Tropical region, since it may protect soil against degradation processes, such as compaction and erosion. The integrated weed management systems consists in selection and use of the different weed control based on cost-benefit analysis, taking into account the benefits to the production system and the environment as important strategies in Conservation Agriculture.

Conservation Agriculture (CA) involves three basic practices: (i) significant reduction of soil tillage and disturbance, (ii) permanent, or at least semi-permanent, soil protection by using crop residues or selected cover crops, and (iii) diversification of crop rotations and intercropping [19]. CA practices often enhance and utilize soil and crop microenviron‐ ments to inhibit germination, growth, and spread of weeds while minimizing the use of synthetic herbicides. Examples of conservation tillage that may fit into a weed manage‐ ment control/suppression program include reduced tillage, cover crops, crop rotation,

Cover crops and cropping residues used in Conservation Agriculture systems serve as a protection for the soil surface against weather aggressions and water erosion, to maintain soil moisture, to suppress weed growth and to provide shelter and food for the soil biota [21]. Also, under Conservation Agriculture regime, the use of crop rotations or intercropping is consid‐ ered essential, as it offers an option for pest/ weed management that is no longer realized

by a portable recording penetrometer [8], and soil load bearing capacity [18].

variable row spacing, and timing of crop planting [20].

row and interrow crop.

2 Weed Biology and Control

soil organic matter.

through soil tillage [22].

Also, perennial crops like coffee crop, eucalyptus plantations and orange orchard are good examples for row-interrow management concept developed by Larson [23] *apud* Pierce and Lal [24]. In this concept, row area is managed to provide a good soil structure for plant germination, emergence, appropriate temperature, moisture, fertility, mechanical strength and weed control for the growth and development of the crop [24].

A well-established, living green manure crop can potentially inhibit the germination and establishment of weeds more effectively than desiccated cover crop residues or areas with natural plant residues [25]. Additional positive benefits to physical and chemical soil proper‐ ties are gained if the cover crop is a legume [26]. Leguminous and other species used as cover crop can release and add chemicals to the system. These substances, known as allelochemicals, can cause beneficial or detrimental effect on other species. This phenomenon is known as allelopathy [27] and is important to be observed when a cover crop is inserted, since there is a species-specific effect, which can inhibit both weeds and crop [28].

According to Meschede, [29], besides the allelopathic effects, a proper use of living mulch/ cover crop can provide control of weed plants by altering of several system features, such as: thermal regimes, incidence of light and physical barriers to emergence, and also increase of rain water retention, soil humidity, organic matter content, microbial activity, predation and overcoming of seed dormancy [29]. Nevertheless, the species cultivated for living mulching/ cover crops must be compatible with the demands of the agricultural system [30].

#### **2. Effects of weed on soil chemical properties in tropical regions**

Many studies done in Tropical conditions have shown the effects of weed control by different methods on soil chemical attributes. A long-term study conducted in a clayey Dystropherric Red Latosol at São Sebastião do Paraíso (Latitude 20°55'00'' S and longitude 47°07'10'' W Greenwich at an altitude of 885 m), State of Minas Gerais, Brazil, showed that different weed control methods in a coffee crop (18 years) affected the components of soil acidity, such as pH, potential acidity (H+Al), exchangeable aluminum (Al) and the saturation aluminum (% m), in both soil layers 0–15 cm and 15–30 cm [31]. The authors observed that no-weed control between coffee rows tends to alkalize soil, on the other hand, the constant use of pre-emergence herbicide acidified it. This increase in pH was attributed to the greater increment of organic matter in areas without weed control/suppression methods [9]. Nevertheless, their results showed that other weed control methods (mechanical mower, disk harrow, rotary tiller, postemergence herbicide and hand weeding) presented intermediate behavior between no-weed control and pre-emergence herbicide.

Other important study was done to determine the effects of weed extracts in the efficiency of lime applied on the soil surface [32]. Their results showed that weed extracts increased soil pH and cycling nutrients, reducing Al up to 20 cm of depth in acid subsoil. The chemical compo‐ sition of the plant material varies with the weeds species. High contents of nitrogen, potassium and calcium were obtained for *Synedrellopsis gresebachii*. The extracts of the plant materials obtained from *Galinsoga parviflora* and *Commelina benghalensis* were the most efficiency for increases pH followed by *Amaranthus hybridus*, *Ricinus communis* and *Parthenium hysterophorus.*

The improvement of the soil fertility proportioned by integrated weed control might be useful to make the plants grow faster and produce higher amount of shoot and root dry mass as well, providing improvements in physical quality of the soil and protecting the soil against physical agents of soil degradation. Also, integrated weed management might be useful to soil and water conservation. In different production systems, many studies done in different regions of Brazil have been shown the improvement in soil organic matter content provided by weeds [14;9;33;18].

Cover crop used as a green manure is other important strategy to management tropical soils and their residues have been reported to negatively affect germination and establishment of weed seeds. For example, as cited before, species that contain a high level of allelochemicals seem well-suited for residue mediated weed suppression. Still, in addition to allelopathic effects, crop residues can exert an effect on weed germination and establishment through other mechanisms, such as competition among crop/weed species for the nutrients released [34].

Besides acting as a tool on weed management, crop residues may also affect the physical properties of the soil. Residue-amended soil may for instance better conserve moisture. Residues left on the soil surface can lead to decreased soil temperature fluctuations and reduced light penetration, which both have been shown to inhibit weed germination [35].

Nevertheless, although there are clear indications about conservation agriculture biophysical and agronomical positive impacts, many unknowns remain about the continuous and complete trades-off in reducing tillage versus soil erosion or weeds control efficiency, or about exporting biomass versus soil protection, soil C storage or nutrient balance [36].

Therefore, there is a continuous need for new approaches and experimental research regarding the application of conservational tillage systems for weed controlling and suppression, the correct choice of cover crops, without causing any deleterious and harmful effects on crop yield and soil properties – whether chemical, physical or biological.

With this chapter, we describe some results of the trials done in Tropical regions related to weed control and cover crops management and its effects on soil and water conservation.

## **3. Field characterization**

matter in areas without weed control/suppression methods [9]. Nevertheless, their results showed that other weed control methods (mechanical mower, disk harrow, rotary tiller, postemergence herbicide and hand weeding) presented intermediate behavior between no-weed

Other important study was done to determine the effects of weed extracts in the efficiency of lime applied on the soil surface [32]. Their results showed that weed extracts increased soil pH and cycling nutrients, reducing Al up to 20 cm of depth in acid subsoil. The chemical compo‐ sition of the plant material varies with the weeds species. High contents of nitrogen, potassium and calcium were obtained for *Synedrellopsis gresebachii*. The extracts of the plant materials obtained from *Galinsoga parviflora* and *Commelina benghalensis* were the most efficiency for increases pH followed by *Amaranthus hybridus*, *Ricinus communis* and *Parthenium hysterophorus.*

The improvement of the soil fertility proportioned by integrated weed control might be useful to make the plants grow faster and produce higher amount of shoot and root dry mass as well, providing improvements in physical quality of the soil and protecting the soil against physical agents of soil degradation. Also, integrated weed management might be useful to soil and water conservation. In different production systems, many studies done in different regions of Brazil have been shown the improvement in soil organic matter content provided by weeds

Cover crop used as a green manure is other important strategy to management tropical soils and their residues have been reported to negatively affect germination and establishment of weed seeds. For example, as cited before, species that contain a high level of allelochemicals seem well-suited for residue mediated weed suppression. Still, in addition to allelopathic effects, crop residues can exert an effect on weed germination and establishment through other mechanisms, such as competition among crop/weed species for the nutrients released [34].

Besides acting as a tool on weed management, crop residues may also affect the physical properties of the soil. Residue-amended soil may for instance better conserve moisture. Residues left on the soil surface can lead to decreased soil temperature fluctuations and reduced light penetration, which both have been shown to inhibit weed germination [35].

Nevertheless, although there are clear indications about conservation agriculture biophysical and agronomical positive impacts, many unknowns remain about the continuous and complete trades-off in reducing tillage versus soil erosion or weeds control efficiency, or about

Therefore, there is a continuous need for new approaches and experimental research regarding the application of conservational tillage systems for weed controlling and suppression, the correct choice of cover crops, without causing any deleterious and harmful effects on crop

With this chapter, we describe some results of the trials done in Tropical regions related to weed control and cover crops management and its effects on soil and water conservation.

exporting biomass versus soil protection, soil C storage or nutrient balance [36].

yield and soil properties – whether chemical, physical or biological.

control and pre-emergence herbicide.

4 Weed Biology and Control

[14;9;33;18].

Some of studies to assess the effects of weed control and cover crops management in coffee plantations have been conducted at the Agronomic Institute of Paraná-IAPAR at Londrina County (Latitude 23 ° 21'30 "S and longitude 51 ° 10'17" W Greenwich), Northern of the Paraná State, Brazil at an average altitude of 550 m.

The soilfrom the Experimental Farm is basalt derived and is classified as a Dystroferric Red Latosol according to the Brazilian Soil Classification System; Typic Haplorthox according to Soil Taxonomy and Ferralsol according to FAO classification. More details about soil charac‐ terization, such as mineralogical composition can be found in Castro Filho and Logan [42].

Between 2008 and 2011, the study area had been planted with common beans and with black oat in the Autumn / Winter. In February 2012, for the establishment of the coffee crop, the preparation was carried out with a furrow plow with 40 cm wide and 30 cm deep. Inside the furrow, 250 g of sedimentary phosphate rock with 10–12 % P2O5 in neutral ammonium citrate solubility and total P2O5 content of 28-30 % was applied per meter. A subsoiling was held within the furrow to a depth of 25 cm to incorporate reactive phosphate. After subsoiling the furrow, 200 g of dolomitic limestone with total neutralizing power-PRNT ot the 75 %, 5 L of poultry litter and 100 g of the fertilizer 04-30-10 N, P2O5 e K2O were applied. Seedlings of coffee cultivar IPR 106 were transplanting at a spacing of 2.5 m (narrower spacing) x 1.0 m (between plants). After eight months, since planting in October 2012, infiltration rates were measured in the newly developed coffee plantation at the rows and between rows.

#### **4. Weed management post planting coffee seedlings**

The weed control methods used in two areas (row and interrow) of coffee plantations during the year 2012 are shown in Table 1. Hand weeding (HAWE): performed with the aid of a hoe, when the weed reached 45 cm height. Between March 2012 and November 2012 it was accomplished five times in the coffee rows and one time in the interrow. Preemergence herbicides (HERB): oxyfluorfen at a rate 4.0 L ha-1 of commercial product at 240 g L-1 (0.96 kg active ingredient ha-1), applied three times in the coffee row during the year of 2012. Brush cutting: accomplished with brush cutter model 2300 Jan® rotor speed 1,750 rpm, equipped with 64 curved knives, swing and reversible, static mass of 735 kg pulled by a tractor model TL 75 New Holland®. Coffee tandem disk harrow (CTDH): the equipment is composed by two sections in tandem; each section is equipped with seven flat disks with cut width of 1.3 m and static mass 300 kg. It's worked at 7 cm depth. Mechanical mowing: accomplished with mower model Rotter TDP 180 Jan® with two knifes with dimensions 1.95 m width and static mass 460 kg.

In August 2014, thirty months after seedling transplantation disturbed soil samples were obtained in two sampling positions of the coffee plantation to assessment the variability of soil chemical properties inside the coffee crop. Soil sampler was a hand gouge auger at four depths: 0–5 cm, 5–10 cm, 10–20 cm, 20–40 cm. In each plot and sampling position, fifteen sample point were taken and to make composite sample. The soil samples were stored in plastics bags and transported to the laboratory. The soil samples were air dried at room temperature in the laboratory and sieved at 2 mm.


Brush cutting-1: brush cutter model 2300 Jan®; Brush cutting-2: central brush cutter model TPPC 0.90 m cutting width; SOIL SAMPLING

**Table 1.** Management of weed in the row and between coffee rows post-planting coffee Cultivar IPR 106 in 2012.

#### **5. Soil analysis**

Chemical analysis of soil (pH in CaCl2, Ca, Mg, K, Al, Cation Exchange Capacity and Total Organic Carbon) were performed on air dried soil-TFSA described in Pavan et al. [38]. Briefly, in an air dried soil samples the pH was determined in a calcium chloride (CaCl2 0.01 mol L-1) at a 1:2.5 ratio (10 cm3 TFSA and 25 mL of H2O). The Ca and Mg content were determined after extraction with potassium chloride (KCl, 1.0 mol L-1) at a ratio of 10 cm3 TFSA to 100 mL extractor, stirring for fifteen minutes and settling for 16 h. Measurements of calcium and magnesium were performed by atomic absorption spectrophotometry-EAA. The K content was determined by flame spectrophotometer after extraction with Mehlich-1 solution (HCl 0.05 mol L-1 H2SO4+0.0125 mol L-1), at a ratio of 10 cm3 TFSA to 100 mL extractor shaking for five minutes and decanted for 16 h.

Extraction H+Al was carried out with Ca (OAc) 2 0.5 mol L-1, pH 7, at ratio of 5 to 75 cm3 TFSA mL extractor 10 min stirring and decanting for 16 h. The cation-exchange capacity (CEC at pH 7.0) was obtained by the sum of Ca+Mg+K+(H+Al). The levels of soil organic carbon were obtained by the wet combustion method with organic carbon oxidation with 5 mL of K2Cr2O7 (potassium dichromate) 0.167 mol L-1 and 10 ml of concentrated H2SO4 (sulfuric acid) concen‐ trate [39].

Physical characterization of the soil was performed by the soil particle-size analysis by the pipette method [40] with chemical dispersion with a 5 mL 1 N sodium hydroxide solution in contact with the samples for 24 hours Mechanical dispersion was accomplished by 2 hours, in a reciprocating shaker, which shakes 180 times per minute in a 38 mm amplitude [41]. Waterdispersible clay was determined by shaking in water as discussed above, except that NaOH was excluded [42].

#### **6. Results and discussion**

0–5 cm, 5–10 cm, 10–20 cm, 20–40 cm. In each plot and sampling position, fifteen sample point were taken and to make composite sample. The soil samples were stored in plastics bags and transported to the laboratory. The soil samples were air dried at room temperature in the

**DATE COFFEE ROW INTERROW** 20/03/2012 Hand weeding and pre-emergence herbicide Hand weeding 08/05/2012 Brush cutting-1

15/06/2012 Disk harrow - CTDH 14/08/2012 Hand weeding Mechanical mowing

22/11/2012 Brush cutting-2

26/12/2012 Brush cutting-2

Brush cutting-1: brush cutter model 2300 Jan®; Brush cutting-2: central brush cutter model TPPC 0.90 m cutting width;

**Table 1.** Management of weed in the row and between coffee rows post-planting coffee Cultivar IPR 106 in 2012.

Chemical analysis of soil (pH in CaCl2, Ca, Mg, K, Al, Cation Exchange Capacity and Total Organic Carbon) were performed on air dried soil-TFSA described in Pavan et al. [38]. Briefly, in an air dried soil samples the pH was determined in a calcium chloride (CaCl2 0.01 mol L-1)

extraction with potassium chloride (KCl, 1.0 mol L-1) at a ratio of 10 cm3 TFSA to 100 mL extractor, stirring for fifteen minutes and settling for 16 h. Measurements of calcium and magnesium were performed by atomic absorption spectrophotometry-EAA. The K content was determined by flame spectrophotometer after extraction with Mehlich-1 solution (HCl 0.05 mol L-1 H2SO4+0.0125 mol L-1), at a ratio of 10 cm3 TFSA to 100 mL extractor shaking for

Extraction H+Al was carried out with Ca (OAc) 2 0.5 mol L-1, pH 7, at ratio of 5 to 75 cm3 TFSA mL extractor 10 min stirring and decanting for 16 h. The cation-exchange capacity (CEC at pH 7.0) was obtained by the sum of Ca+Mg+K+(H+Al). The levels of soil organic carbon were

TFSA and 25 mL of H2O). The Ca and Mg content were determined after

laboratory and sieved at 2 mm.

6 Weed Biology and Control

SOIL SAMPLING

**5. Soil analysis**

at a 1:2.5 ratio (10 cm3

five minutes and decanted for 16 h.

10/06/2012 Hand weeding

09/10/2012 Hand weeding 22/10/2012 Pre-emergence herbicide

27/11/2012 Hand weeding 06/12/2012 Pre-emergence herbicide Chemical and physical properties of a very clayey Dystropherric Red Latosol (Typic Haplor‐ thox) at four depths in two sampling of positions of the coffee plantation Cultivar IPR 106 are given in Table 2. Soil pH values observed in the four soil depths in both sampling positions are considered low, providing higher soil acidity. Nevertheless those pH parameters are still lower than recommended for the growth and development of coffee in Paraná [43]. Although, the pH can be found inappropriate for coffee growth and development, these values are typical for the Latosol of this study cultivated with coffee [43; 15]. According to the later authors, in the state of Paraná, Brazil, soil acidity is an ongoing process in soils planted with coffee (*Coffea arabica* L.) because rainfall exceeds evapotranspiration and also, due to soil erosion and leaching [15].

In both sampling position of the coffee crop, the total soil organic carbon decreased with the depth (Table 2). Highest total soil organic carbon was found in the 0–5 cm depth as a result of the weed control and deposition of the straw from weeds. These results are similar to observed by Pavan et al. [15].

Among the sampling position, highest variability was for soil phosphorus. A high rate of this nutrient was added at the row area at the time of the planting coffee seedlings.

In each soil depth, the Al exchangeable increased in the inter row in relation to coffee row.

As can be seen from the data presented in Table 1, the chemical properties of the soil in the coffee row is most suitable for plant growth at all depths, which is assigned to the differential management of the crop rows relative to the lines. Besides the application of mineral fertilizers and non-revolving, the specific soil management of perennial crops which gives the soil a variation both vertically and horizontally [47], the weeds in the interrows were managed with the rotary crusher method mechanical weed control.

In both sampling position, water-dispersible clay are similar in two first soil layers (Table 2). It is important to highlight that for this soil, water-dispersible clay has close relationship in soil pH as demonstrated by Castro Filho and Logan [37]. However, the authors suggested that organic matter contentis more importantto aggregate stability andsoil erodibility than soilpH.


TOC – total organic carbon content; CEC – Cation-exchange capacity; WDC – Water-dispersible clay.

**Table 2.** Chemical and physical properties of a Dystropherric Red Latosol (Typic Haplorthox) very clayey in the Agronomic Institute of Paraná at Londrina coffee plantation Cultivar IPR 106.

It was observed in the field, that the mechanical weed control with brush cutter instead of mechanical mower promoted homogeneous distributions of the residue of the weed on the soil surface. With the brush cutter, in the interrow area is possible to create a rough surface to maximize infiltration rate and inhibit germination of weed seeds in addition increases on soil load bearing capacity to wheel traffic. This increase on soil load bearing capacity proportioned by brush cutter decreased soil compaction in relation to the soil managed with disk harrow, mechanical mower and cover crop (*Arachis pintoi*) as described by Pais et al. [11].

## **7. Rainfall simulations**

**SAMPLING POSITION**

**--------------------- COFFEE ROW --------------------- --------------------- INTERROW --------------------- 0 – 5 cm 5 – 10 cm 10 – 20 cm 20 – 40 cm 0 – 5 cm 5 – 10 cm 10 – 20 cm 20 – 40 cm**

pH: CaCl2 4.70 4.20 4.30 4.30 4.40 4.00 3.90 3.90 Al, cmolc dm-3 0.19 0.83 0.57 0.60 0.49 1.25 1.70 1.56 H + Al, cmolc dm-3 7.20 9.70 8.35 7.75 8.35 10.45 10.45 9.70 TOC, g dm-3 18.31 17.76 14.76 12.81 17.49 15.19 12.35 10.79 P, mg dm-3 101.5 77.7 110.0 49.1 24.2 12.8 4.1 4.2 Ca, cmolc dm-3 5.75 3.57 4.25 3.75 2.77 1.47 1.12 1.45 Mg, cmolc dm-3 1.64 0.94 0.90 0.98 1.52 0.57 0.37 0.53 K, cmolc dm-3 0.65 0.30 0.27 0.20 1.50 1.05 0.75 0.71 SB, cmolc dm-3 8.04 4.81 5.42 4.93 5.79 3.09 2.24 2.69 Ratio Ca:Mg 3.51 3.80 4.72 3.83 1.82 2.58 3.03 2.74 Ratio Ca:K 8.85 11.90 15.74 18.75 1.85 1.40 1.49 2.04 Ratio Mg:K 2.52 3.13 3.33 4.90 1.01 0.54 0.49 0.75 CEC, cmolc dm-3 15.24 14.51 13.77 12.68 14.14 13.54 12.69 12.39 V, % 52.75 33.14 39.36 38.88 40.94 22.82 17.65 21.71 Saturation Al, % 2.30 14.71 9.51 10.84 7.80 28.80 43.14 36.70 Ca / CEC, % 37.73 24.60 30.86 29.57 19.59 10.86 8.83 11.70 Mg / CEC, % 10.76 6.48 6.54 7.73 10.75 4.21 2.92 4.28 K / CEC, % 1.72 1.22 0.87 0.68 7.66 9.67 8.50 6.07 Clay, dag kg-1 80 80 82 81 80 80 82 82 Silt, dag kg-1 15 14 14 15 14 14 13 14 Sand, dag kg-1 5 6 4 4 5 6 5 4 WDC, dag kg-1 68 66 65 5 69 65 2 1

TOC – total organic carbon content; CEC – Cation-exchange capacity; WDC – Water-dispersible clay.

mechanical mower and cover crop (*Arachis pintoi*) as described by Pais et al. [11].

Agronomic Institute of Paraná at Londrina coffee plantation Cultivar IPR 106.

**Table 2.** Chemical and physical properties of a Dystropherric Red Latosol (Typic Haplorthox) very clayey in the

It was observed in the field, that the mechanical weed control with brush cutter instead of mechanical mower promoted homogeneous distributions of the residue of the weed on the soil surface. With the brush cutter, in the interrow area is possible to create a rough surface to maximize infiltration rate and inhibit germination of weed seeds in addition increases on soil load bearing capacity to wheel traffic. This increase on soil load bearing capacity proportioned by brush cutter decreased soil compaction in relation to the soil managed with disk harrow,

**PROPERTIES**

8 Weed Biology and Control

In tropical regions, infiltration rate and hydraulic conductivity are the most important soil physical properties to understand the hydric erosion. This way, the determination of infiltra‐ tion rates plays an important role because of the direct interrelation between erosion and infiltrability [45] and water movement to downwards layer of the soil profile.

In the field trial, infiltration rate and water and soil losses were measured using a portable. In this equipment, the drops falls inside the metal frame and the infiltration rate is calculated as the difference between rainfall intensity and runoff [46]. The rain simulator operated with rainfall intensity adjusted to 85 mm h-1, which represent the maximum rainfall intensity to Londrina, State of Paraná, Brazil. Runoff was collected through a spout and measured every minute.

The metal frame from rainfall simulator was installed in two positions in relation to the rows of the coffee plantation and in the interrows; weeds covered 100 % of the soil surface and between coffee plants without weed and bare soil.

As illustrated by Figure 1, the infiltration rate in the interrow area under weed cover was 100 % (85 mm h-1) after 60 minutes. In contrast, the infiltration rate in the coffee row area without weed cover was 7 mm h-1, which represent runoff equal to 78 mm h-1. The highest infiltration rate of water into the soil observed in the interrow after 60 minutes may be due to interception of raindrops provided by shoots of weeds in this area. Furthermore, as mentioned earlier, the soil surface between coffee rows are covered by the residues from the brush cutter which probably increases create a rough surface to maximize infiltration rate and inhibit germination of weed seeds, lower occurrence of surface crusting and soil compaction.

These results demonstrated the importance of maintaining permanent vegetative cover on the soil surface. This technique is especially important during the Spring / Summer season period with high intensity of rainfall in the tropical region and erosivity.

In the interrow area, the soil surface was 100 % of the area covered by weeds. On the other hand, in the row area the weeds were removed to provide the growth and development of the crop the soil was exposure without cover (data not shown). As pointed by Yang et al. [12] in perennial crops, weeds covered bare soil and prevented erosion during the rainy season in summer. Due to that is so important cover the soil surface in all areas included the row inside the coffee crop like shown in the Figure 2. This technique improves the water infiltration rate in the row area, and increases the availability water capacity to the coffee.

The weeds between coffee rows play an important role in water dynamics by intercepting raindrops impacts against soil surface, which probably reduces surface crusting and maintains a constant infiltration of water for one hour. On the other hand, in the coffee rows, weeds are controlled to provide the maximum growth and development of the coffee plants. By exclusion of the weeds there is a direct impact of raindrops on the soil surface, which reduces infiltration sharply due to the formation of surface crusting. Thus, a strategy to minimize soil loss and water after planting of perennial crops is to make mulch using waste weed (Figure 2).

**Figure 1.** Water infiltration rates in two positions of the coffee plantation after 60 minutes of rainfall intensity of the 85 mm h-1.

As mentioned earlier in the row area, weeds are controlled to provide the maximum growth and development of the coffee plants. In this region, the infiltration rate decreased to 7 mm h-1 at the 60 minutes (Figure 1) and the runoff began seven minutes after rainfall (Figure 3 and Figure 4). On the other hand, the infiltration rate in the interrow area between coffee rows where the weeds protect the soil surface, the infiltration rate was 85 mm h-1 at the 60 minutes of the rainfall intensity. In this region, there is a great influence of the brush cutting for weed control which promoted homogeneous distributions of the residue of the weed on the soil surface and protect the soil surface against raindrop impact.

By evaluating the effects of no-tillage on infiltration rate in the same soil analyzed in this study, Roth et al. [45] observed the constant infiltration rate to 10 min with rainfall intensity of the 68 mm h-1. The authors highlighted that in no-tillage plot the infiltration rate decreased to about 5 mm h-1 after 60 minutes. Also, they observed that runoff usually starter about 4-6 minutes after the began of rainfall. The data from present study showed that runoff starter 7 minutes after the rainfall began.

Thus, the weeds have great influence on water dynamics in this agrosystem and higher impacts on erosion due rainfall intensity will occur in the row area without soil cover (Figure 1). In this context, weed and cover crops between rows of the perennial crops helps to protect the soil against physical degradation processes.

The rainfall simulation time explain 75 % of the variation of the runoff (Figure 4) significant at 1 % probability level, by t-Student test.

Conservation Agriculture include reduced runoff, improved nutrient cycling, reduced soil degradation, reduced soil and water pollution, and enhanced activities of soil biota [47].

The Role of Weed and Cover Crops on Soil and Water Conservation in a Tropical Region http://dx.doi.org/10.5772/59952 11

As mentioned earlier in the row area, weeds are controlled to provide the maximum growth and development of the coffee plants. In this region, the infiltration rate decreased to 7 mm h-1 at the 60 minutes (Figure 1) and the runoff began seven minutes after rainfall (Figure 3 and Figure 4). On the other hand, the infiltration rate in the interrow area between coffee rows where the weeds protect the soil surface, the infiltration rate was 85 mm h-1 at the 60 minutes of the rainfall intensity. In this region, there is a great influence of the brush cutting for weed control which promoted homogeneous distributions of the residue of the weed on the soil

**Figure 1.** Water infiltration rates in two positions of the coffee plantation after 60 minutes of rainfall intensity of

By evaluating the effects of no-tillage on infiltration rate in the same soil analyzed in this study, Roth et al. [45] observed the constant infiltration rate to 10 min with rainfall intensity of the 68 mm h-1. The authors highlighted that in no-tillage plot the infiltration rate decreased to about 5 mm h-1 after 60 minutes. Also, they observed that runoff usually starter about 4-6 minutes after the began of rainfall. The data from present study showed that runoff starter 7 minutes

Thus, the weeds have great influence on water dynamics in this agrosystem and higher impacts on erosion due rainfall intensity will occur in the row area without soil cover (Figure 1). In this context, weed and cover crops between rows of the perennial crops helps to protect the soil

The rainfall simulation time explain 75 % of the variation of the runoff (Figure 4) significant

Conservation Agriculture include reduced runoff, improved nutrient cycling, reduced soil degradation, reduced soil and water pollution, and enhanced activities of soil biota [47].

surface and protect the soil surface against raindrop impact.

after the rainfall began.

the 85 mm h-1.

10 Weed Biology and Control

against physical degradation processes.

at 1 % probability level, by t-Student test.

**Figure 2.** Straw from weed used as mulch applied post-planting coffee seedlings for protection of the coffee row area against the direct impact of raindrops and surface crusting.

Our results showed that integrate weed control using the managing zones (row and interrow area) within the coffee crop in Tropical conditions are essentials for soil and water conservation and help the basic principle for Conservation Agriculture. This may suggest that, weed control has a high influence on soil chemical properties, water infiltration rate and runoff.

It is still a challenge to set a suitable weed control in terms of cover crops and soil quality maintenance. Weed control methods can lead to significant changes on soil organic matter which affects soil quality. Nevertheless, taking into account the dynamic character, the response to different weed control systems and the urgency on environmentally safe solutions there is a continuous need on ongoing soil science research in order to achieve suitable conservational practices.

**Figure 3.** Water infiltration rate in the coffee row area without weed, on a very clayey (80 dag kg-1 clay) Typical Hap‐ lorthox, at the Agronomic Institute of Paraná – IAPAR, Experimental Station in Londrina, State of Paraná, Brazil. Rain‐ fall intensity 85 mm h-1.

**Figure 4.** Runoff in the coffee row area without weed, on a very clayey (80 dag kg-1 clay) Typical Haplorthox, at the Agronomic Institute of Paraná – IAPAR, Experimental Station in Londrina, State of Paraná, Brazil. Rainfall in‐ tensity 85 mm h-1.

#### **Acknowledgements**

This study was funded by Agronomic Institute of Paraná – IAPAR, Coffee Program Research. Also, we appreciate the Coffee Research Consortium for projects financed with funds from the Coffee Economy Defense-FUNCAFÉ the Ministry of Agriculture, Livestock and Food Supply – MAPA. We also, are grateful to Brazilian Federal Agency for Support and Evaluation of Graduate Education – CAPES, Foundation within the Ministry of Education in Brazil for awarding scholarship grant to second author throughout Post-Doctoral National Program – PNPD.

### **Author details**

**Figure 3.** Water infiltration rate in the coffee row area without weed, on a very clayey (80 dag kg-1 clay) Typical Hap‐ lorthox, at the Agronomic Institute of Paraná – IAPAR, Experimental Station in Londrina, State of Paraná, Brazil. Rain‐

**Figure 4.** Runoff in the coffee row area without weed, on a very clayey (80 dag kg-1 clay) Typical Haplorthox, at the Agronomic Institute of Paraná – IAPAR, Experimental Station in Londrina, State of Paraná, Brazil. Rainfall in‐

fall intensity 85 mm h-1.

12 Weed Biology and Control

tensity 85 mm h-1.

Cezar Francisco Araujo-Junior1\*, Bruno Henrique Martins1 , Vinicius Yugi Higashi1,2 and Carlos Alberto Hamanaka1,3

\*Address all correspondence to: cezar\_araujo@iapar.br

1 Agronomic Institute of Paraná – IAPAR, Rodovia Celso Garcia Cid, Londrina – State of Paraná, Brazil

2 Scientific Initiation Program at Agronomic Institute of Paraná ProICI-IAPAR, Federal University Technology of Paraná – UTFPR, Londrina – PR, Brazil

3 Scientific Development and Innovation Grant from Brazilian Consortium for Coffee Research, Brazil

#### **References**


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16 Weed Biology and Control

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atualizada).


## **Weed Control by Chemical and Mechanical Means**

Algirdas Jasinskas, Dainius Steponavičius, Povilas Šniauka and Remigijus Zinkevičius

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/60002

#### **1. Introduction**

Crop production is one of the most important agriculture industries in an agricultural country. It involves not only the land, as the primary means of agricultural production, with all the biological processes taking place in it, but also the surrounding environment, the sun, living nature, the plants and the wide variety of techniques, instruments, tools and implements that are used. People are the main, active participants in the production process, involved in implementing and promoting it, as well as in educating others about it. Generally, there is a closely interacting complex of production factors determining the final outcome of the process, its quantitative and qualitative indicators.

In any case, when planning to perform one or other plant operation, tillage, sowing or crop care activity, one first of all needs to choose the proper, complete, correct technical equipment (machines, tools, operational parts), so that the negative impact on the living environment of the technological operations is minimal: the soil, the activity of microorganisms, the plants and environment, and the quality of work should all be maintained to the highest degree. By knowing the characteristics of the material, we can properly select the technical measure or construction for the intended job; this choice will affect the quality of the work's performance. Performing technological research, implementing and applying the prospective agriculture production technology and increasing production volume, the technology engineering professional has to not only know the engineering issues, but also absorb the agronomic and economic aspects of agricultural production.

An important link in the chain of technological crop supervision is weed control. In order to perform this technological operation properly, it is important to know the characteristics of weeds and properly select technical-technological measures to destroy them. The most commonly used and the most effective plant care and weed control methods are chemical

© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and eproduction in any medium, provided the original work is properly cited.

(using loose and liquid chemical products) and mechanical (using agricultural implements, cultivators and harrows). These basic weed control techniques will be analysed in this educational book.

The book *Weed* Biology and Control is intended for researchers and students of institutions of higher education and universities. We also believe that this educational book will interest not only the target groups of students, but also specialists in agricultural companies and farmers.

The authors of this educational work express their sincere gratitude to the reviewers for their valuable comments and suggestions that have helped improve the quality of the book.

### **2. Weed control by chemical means**

Plant protection machines using chemical products are classified into the following groups:


#### **2.1. Requirements for sprayers and distribution techniques of plant protection products**

Modern plant protection is more than just the use of appropriate agents. Liquid droplets of a working liquid should cover the tillable surfaces as evenly as possible. Only then can we expect the optimal result. Apart from this, when protecting the environment, no loss should arise due to drift of liquid droplets downwind, dripping or evaporation. For these reasons, very high demands are made on modern plant protection products, especially sprayers. The accuracy requirements for nozzles that are made today were simply impossible to fulfil several years ago.

The success of plant protection depends not only on the proper selection of a preparation and its optimal usage time, but also on the use of technology.

#### *2.1.1. Requirements for sprayers*

Sprayer pace should be free of defects. Pump capacity and the formed pressure should meet the technical characteristics of the sprayer. Performance deviations should not exceed 10 %. Measurements should be carried out having reached the nominal performance of 0.5 MPa (5 bar) pressure. Pump pressure pulsation levelling equipment should work properly. The safety valve has to work reliably. The pump must be sealed.

When the pump is running at nominal speed, the movement of the mixing solution in the tank should be clearly visible. The reservoir and the lid of the filling hole should be sealed; a sieve should be present in the filling hole, and the solution level scale should be clearly visible. There should be the possibility to collect all solution that is drained in the reservoir. Sprayer filling and devices for washing packages of preparations should operate. The filling device should have a non-return valve.

(using loose and liquid chemical products) and mechanical (using agricultural implements, cultivators and harrows). These basic weed control techniques will be analysed in this

The book *Weed* Biology and Control is intended for researchers and students of institutions of higher education and universities. We also believe that this educational book will interest not only the target groups of students, but also specialists in agricultural companies and farmers. The authors of this educational work express their sincere gratitude to the reviewers for their valuable comments and suggestions that have helped improve the quality of the book.

Plant protection machines using chemical products are classified into the following groups:

**•** Powder distributors, spreading toxic powder on trees and plants which are infested with

**2.1. Requirements for sprayers and distribution techniques of plant protection products**

Modern plant protection is more than just the use of appropriate agents. Liquid droplets of a working liquid should cover the tillable surfaces as evenly as possible. Only then can we expect the optimal result. Apart from this, when protecting the environment, no loss should arise due to drift of liquid droplets downwind, dripping or evaporation. For these reasons, very high demands are made on modern plant protection products, especially sprayers. The accuracy requirements for nozzles that are made today were simply impossible to fulfil several years

The success of plant protection depends not only on the proper selection of a preparation and

Sprayer pace should be free of defects. Pump capacity and the formed pressure should meet the technical characteristics of the sprayer. Performance deviations should not exceed 10 %. Measurements should be carried out having reached the nominal performance of 0.5 MPa (5 bar) pressure. Pump pressure pulsation levelling equipment should work properly. The safety

When the pump is running at nominal speed, the movement of the mixing solution in the tank should be clearly visible. The reservoir and the lid of the filling hole should be sealed; a sieve should be present in the filling hole, and the solution level scale should be clearly visible. There

**•** Sprayers, spraying the soil or plants with small poisonous liquid droplets;

**•** Fumigators used for the injection of fast-steaming toxic liquid into the soil;

educational book.

20 Weed Biology and Control

pests;

ago.

**2. Weed control by chemical means**

**•** Pickling machines used for dry or wet seed pickling.

its optimal usage time, but also on the use of technology.

valve has to work reliably. The pump must be sealed.

*2.1.1. Requirements for sprayers*

All pressure measurement, control and monitoring devices should be *operating and sealed*. In the control board of a garden sprayer, a switch-off button on the right and left sections should be present. Manometer scale must be greater than the maximum pressure developed by the spray. Manometer scale limits should be higher than the maximal pressure of the sprayer. If the working pressure is up to 0.5 MPa (5 bar), the value of a manometer scale division should not exceed 0.02 MPa (0.2 bar). The minimal frame diameter of a manometer is 63 mm; the measuring error should not exceed ± 0.02 MPa (0.2 bar).

The pipe system should be leak-proof, hoses should not be bent *or* broken, and should be wellfitted; they should not interfere with the spray gun parts or be sprayed.

At least one filter should be present in suction and pressure lines, and its net size should comply with the indications of sprayer producers. Filters should be *sealed* and undamaged.

The sprayer beam should be straight and stable in all directions. A beam longer than 10 m should be associated with a device allowing it to swing back *when meeting* the barrier. *Equal* spacing should be obtained between the nozzles and from the nozzle to *the treated* plants. The sprayer parts cannot be sprayed over. Beams longer than 10 m should have protections at the ends. If the length of a beam section is longer than 6 m, a folding device should be present. Beam lifting and damping devices should function properly.

All nozzles, filters and their instant shut-off valves should be compatible with each other; their types and sizes should *not* differ. Upon termination of spraying, there should be no dripping through the nozzles. Spreading uniformity of the sprayed solution droplets is described by a coefficient of the variation of transverse distribution, which is measured by an electronic bench with gutters, and should not exceed 15 %. While measuring transverse distribution by the manual tray with gutters and indicators showing the average meaning, no more than 15 % of cups should indicate a ± 15 % deviation from the average meaning. In the absence of meas‐ urement stands with gutters, smoothness of spraying may be temporarily established by special flow meters. They are used to measure performance of all nozzles located on a beam. The error of each nozzle performance should not exceed ± 5 %, compared to the average, or 15 % compared with the performance data of new nozzles indicated in the manufacturer's instructions. Spraying uniformity for pneumohydraulic garden sprayers is determined by measuring the performance of each nozzle. Their indication accuracy should not exceed ± 10 % compared to the average, or 15 % compared with the performance data of new nozzles indicated in manufacturer's instructions. The difference between inputs delivered to the left and right *side* cannot exceed 10 %. Spraying nozzles on the left and right sides of the garden sprayer should be identical. The maximum pressure difference in the nozzle should not exceed 15 %. The fan in the garden sprayer should have a separate switch; the air diversion device should operate *properly*; the sprayer parts cannot be sprayed over.

Sprayers must be designed in such a way that they are used to avoid downwind drift of a dangerous solution (fan with air intake channels, special nozzles reducing drift downwind, and so on).

#### *2.1.2. Application techniques of plant protection products*

Powder or granules of plant protection products may be simply scattered on the ground. The main point in this case is that there is no need for water, a low norm of preparation and high performance. Scattered plant protection products work for a long time; active substances excrete continuously. Work expenses for spreading the preparations are low. The biggest problem here is choosing the exact dosage and evenly spreading the plant protection products.

Liquid products, or those dissolved in water or mixed with water may be evenly sprayed on the plants or the soil surface and spread in the form of mist or spray.

The spray method is widely used because of the low risk to the user and the low danger of preparation drifting downwind. However, spraying of plant protection products requires a great deal of water, and is marked by high expenses and labour costs compared to relatively low productivity. The size of sprayed drops varies from 100 to 1000 µm.

Spreading plant protection products in the form of mist requires less water, and work efficiency is higher; expenses and labour costs also reduce. In addition, drops of preparation penetrate into the foliage. However, in this case, much power is needed to turn the fan; due to the higher concentration and drift of drops downwind, a higher risk to the user, the sprayed plants and the growing crop arises. The size of sprayed drops varies from 50 to 150 µm.

The most efficient work is achieved when spreading plant protection products in the form of mist. In this case, the need for water is very little, or water is not needed at all. Expenses and labour costs are also very low. Apart from this, plant protection products penetrate to hardto-reach places, and they are not washed away by the rain. However, in this case, we are very dependent on natural conditions; users must wear personal protection equipment since the drift of drops presents a serious risk to plants and environment. The size of the sprayed drops is less than 50 µm.

The quality of spraying of plant protection products depends on many factors. They may be divided into four groups:


The most important technical *requirements* for the sprayer are as follows: spray norm; running speed of a spray aggregate; operating pressure; spray height; nozzle type and spray angle; and the lateral distribution of the sprayed solution. Droplet formation and movement are affected by their size, speed, flight path and attack angle when reaching the pattern surface.

The pattern coverage ratio depends on the physical and chemical properties of the plant protection product or solution: concentration, viscosity, etc. The quality of spraying of plant protection products also depends on the size of leaves of a treated plant, hairiness, veininess, wax layer, crops density and height. The pattern coverage ratio also depends on the wind speed, relative humidity, temperature, and processes of thermals.

#### **2.2. Sprayers**

*2.1.2. Application techniques of plant protection products*

is less than 50 µm.

22 Weed Biology and Control

divided into four groups:

**•** The sprayed plant; **•** Climatic conditions.

the plants or the soil surface and spread in the form of mist or spray.

low productivity. The size of sprayed drops varies from 100 to 1000 µm.

the growing crop arises. The size of sprayed drops varies from 50 to 150 µm.

**•** Technical requirements for the sprayer, droplet formation and movement;

**•** Physical and technical properties of a product and solution (product + water);

by their size, speed, flight path and attack angle when reaching the pattern surface.

speed, relative humidity, temperature, and processes of thermals.

Powder or granules of plant protection products may be simply scattered on the ground. The main point in this case is that there is no need for water, a low norm of preparation and high performance. Scattered plant protection products work for a long time; active substances excrete continuously. Work expenses for spreading the preparations are low. The biggest problem here is choosing the exact dosage and evenly spreading the plant protection products. Liquid products, or those dissolved in water or mixed with water may be evenly sprayed on

The spray method is widely used because of the low risk to the user and the low danger of preparation drifting downwind. However, spraying of plant protection products requires a great deal of water, and is marked by high expenses and labour costs compared to relatively

Spreading plant protection products in the form of mist requires less water, and work efficiency is higher; expenses and labour costs also reduce. In addition, drops of preparation penetrate into the foliage. However, in this case, much power is needed to turn the fan; due to the higher concentration and drift of drops downwind, a higher risk to the user, the sprayed plants and

The most efficient work is achieved when spreading plant protection products in the form of mist. In this case, the need for water is very little, or water is not needed at all. Expenses and labour costs are also very low. Apart from this, plant protection products penetrate to hardto-reach places, and they are not washed away by the rain. However, in this case, we are very dependent on natural conditions; users must wear personal protection equipment since the drift of drops presents a serious risk to plants and environment. The size of the sprayed drops

The quality of spraying of plant protection products depends on many factors. They may be

The most important technical *requirements* for the sprayer are as follows: spray norm; running speed of a spray aggregate; operating pressure; spray height; nozzle type and spray angle; and the lateral distribution of the sprayed solution. Droplet formation and movement are affected

The pattern coverage ratio depends on the physical and chemical properties of the plant protection product or solution: concentration, viscosity, etc. The quality of spraying of plant protection products also depends on the size of leaves of a treated plant, hairiness, veininess, wax layer, crops density and height. The pattern coverage ratio also depends on the wind

#### *2.2.1. Sprayer classification*

Sprayers are classified according to a variety of features: power source, destination and spraying method (Table 1).


#### **Table 1.** Sprayer classification

Tractor sprayers may be suspended, tractor-drawn and put-on. Aerosol sprayers are also classified into cold and hot smoke. Powered sprayers may be carried on the back or trans‐ ported. Powered sprayers carried on the back are usually pneumohydraulic, and transported ones hydraulic. Manual sprayers may be carried on the back or held in the hands. Portable hand-held sprayers may be equipped with a pump, with a spray pipe or without it. Backcarried sprayers may have either a piston or a diaphragm pump. Hand-held sprayers are usually hydraulic.

#### *2.2.2. Structure of tractor-mounted hydraulic field sprayers*

Tractor-mounted hydraulic field sprayers are usually used for spraying plant protection products on the plants. The main parts of a tractor-mounted hydraulic field sprayer are the spray tank, pump, control equipment, filters, beam, injectors, equipment to pour agents into the tank, and equipment to wash the exterior of the sprayers and the frame.

The tractor-mounted hydraulic field sprayer works as follows (Figure 1): connector 32 is connected to a hydrant fill hose, and, having opened valve 27, three-quarters of the capacity of spray tank 1 is filled with water. Plant protection products are added to the preparation tank 34, and, having opened valve 35, the required preparation quantity is poured into the spray tank.

Powdered preparation or a higher quantity of carbamide is dissolved in the reservoir 15 by one of the taps 16 having turned on the nozzles 17 that are located in the arch. The tap 12 turns on the hydraulic blender 33. Having turned on the injector 13 by the tap 14, the dissolved products are added to the spray tank. Empty preparation utensils are washed with water three times by the nozzle 18, and the washings are poured into the spray tank. If the fluid does not reach the mark, more water should be added. Fluid mixing intensity may be changed by the tap 12. Having prepared the required quantity of spray liquid, the pump 6 draws solution from the reservoir 1 through the filter 5, and from the self-cleaning pressure line filter 8 delivers it to the control panel. Having set the required pressure by the reducing valve 7, the solution is supplied from the control panel to the hydraulic mixer 33, injector, preparation tanks and sections of spray bar 11 with nozzles. Nozzles spray the liquid on the sprayed surfaces. The surplus of the solution gets back into the tank by reversible lines. Having completed the work, residues of the sprayed liquid should be diluted with water at least 10 times and sprayed in the sprayed field. The empty interior of the sprayer should be twice washed by the rotating spray nozzle 20; some clean water should be added from tank 2 (about 10 % of the tank capacity). After each rinse, the contents of the sprayer tank should be sprayed in the field. The exterior of the sprayer is washed outside or in a special washing area. A small tank 24 for washing hands should be installed in a convenient place.

<sup>1 –</sup> tank; 2 – clean water tank; 3 – joint to connect suction hose to pump; 4 – joint to connect suction hose to injector; 5 – suction line filter; 6 – pump; 7 – reduction valve; 8 – self-cleaning pressure line filter; 9 – beam sections' control valves; 10 – manometer; 11 – beam section with nozzles; 12 – tap to adjust the intensity of liquid mixing; 13 – injector; 14 – injector control tap; 15 – tank to dissolve the powdered products; 16 – taps; 17 – nozzles located in the arch form; 18 – rotating nozzle; 19 – tap for turning the tank on and off; 20 – rotating tank wash nozzle; 21 – strainer; 22 – filler hole lid; 23 – remote-control box (spraying computer); 24 – clean water tank; 25 and 26 – a storage place; 27 – filling line tap; 28 – tap to turn the washing brush on and off ; 29 – drum for collection of washing hose; 30 – brush for washing the sprayer exterior; 31 – liquid level scale; 32 – filling hose connector to connect to the hydrant; 33 – hydraulic blender; 34 – preparation tank with rotating nozzle; 35 – shut-off valve [1]. *Suspended field tractor-mounted hydraulic sprayers* are mounted on the rear hydraulic lift of a tractor, and their entire 1 – tank; 2 – clean water tank; 3 – joint to connect suction hose to pump; 4 – joint to connect suction hose to injector; 5 – suction line filter; 6 – pump; 7 – reduction valve; 8 – self-cleaning pressure line filter; 9 – beam sections' control valves; 10 – manometer; 11 – beam section with nozzles; 12 – tap to adjust the intensity of liquid mixing; 13 – injector; 14 – injector control tap; 15 – tank to dissolve the powdered products; 16 – taps; 17 – nozzles located in the arch form; 18 – rotating nozzle; 19 – tap for turning the tank on and off; 20 – rotating tank wash nozzle; 21 – strainer; 22 – filler hole lid; 23 – remote-control box (spraying computer); 24 – clean water tank; 25 and 26 – a storage place; 27 – filling line tap; 28 – tap to turn the washing brush on and off ; 29 – drum for collection of washing hose; 30 – brush for washing the sprayer exterior; 31 – liquid level scale; 32 – filling hose connector to connect to the hydrant; 33 – hydraulic blender; 34 – preparation tank with rotating nozzle; 35 – shut-off valve [1].

1800 l, and operational width ranges from 6 to 24 m. **Figure 1.** Scheme of tractor-mounted hydraulic field sprayer

8 7

Figure 2. Suspended field tractor-mounted hydraulic sprayer:

Figure 1. Scheme of tractor-mounted hydraulic field sprayer:

1 2 Suspended field tractor-mounted hydraulic sprayers are mounted on the rear hydraulic lift of a tractor, and their entire weight during operation and transportation falls on the tractor wheels (Figure 2). Their tank capacity ranges from 300 to 1800 l, and operational width ranges from 6 to 24 m.

6 3 5

weight during operation and transportation falls on the tractor wheels (Figure 2). Their tank capacity ranges from 300 to

1 – tank for the sprayed fluid; 2 – the tank of clean water; 3 – preparation tank; 4 – three-position (spray-rinse-dilution) tap; 5 – pump; 6 – frame with supports; 7 – remote-control panel with computer; 8 – beam with nozzles [1].

**Figure 2.** Suspended field tractor-mounted hydraulic sprayer

to the control panel. Having set the required pressure by the reducing valve 7, the solution is supplied from the control panel to the hydraulic mixer 33, injector, preparation tanks and sections of spray bar 11 with nozzles. Nozzles spray the liquid on the sprayed surfaces. The surplus of the solution gets back into the tank by reversible lines. Having completed the work, residues of the sprayed liquid should be diluted with water at least 10 times and sprayed in the sprayed field. The empty interior of the sprayer should be twice washed by the rotating spray nozzle 20; some clean water should be added from tank 2 (about 10 % of the tank capacity). After each rinse, the contents of the sprayer tank should be sprayed in the field. The exterior of the sprayer is washed outside or in a special washing area. A small tank 24 for

2

14 16 18

17 15 32 35

hidraulinio maišiklio pripildymo liplovimo lini-

hydraulic mixer filling washing

34

24

29

30

11

27

washing hands should be installed in a convenient place.

26

siurbimo slėgio linija

suction pressure injector suction feedback

inžektoriaus siurbimo grįžtamosios lini-

10

Figure 1. Scheme of tractor-mounted hydraulic field sprayer:

preparation tank with rotating nozzle; 35 – shut-off valve [1].

– preparation tank with rotating nozzle; 35 – shut-off valve [1].

8 7

Figure 2. Suspended field tractor-mounted hydraulic sprayer:

1800 l, and operational width ranges from 6 to 24 m.

**Figure 1.** Scheme of tractor-mounted hydraulic field sprayer

12 19

28

8 7 20

33

6 5 3

1 – tank; 2 – clean water tank; 3 – joint to connect suction hose to pump; 4 – joint to connect suction hose to injector; 5 – suction line filter; 6 – pump; 7 – reduction valve; 8 – self-cleaning pressure line filter; 9 – beam sections' control valves; 10 – manometer; 11 – beam section with nozzles; 12 – tap to adjust the intensity of liquid mixing; 13 – injector; 14 – injector control tap; 15 – tank to dissolve the powdered products; 16 – taps; 17 – nozzles located in the arch form; 18 – rotating nozzle; 19 – tap for turning the tank on and off; 20 – rotating tank wash nozzle; 21 – strainer; 22 – filler hole lid; 23 – remote-control box (spraying computer); 24 – clean water tank; 25 and 26 – a storage place; 27 – filling line tap; 28 – tap to turn the washing brush on and off ; 29 – drum for collection of washing hose; 30 – brush for washing the sprayer exterior; 31 – liquid level scale; 32 – filling hose connector to connect to the hydrant; 33 – hydraulic blender; 34 –

1 – tank; 2 – clean water tank; 3 – joint to connect suction hose to pump; 4 – joint to connect suction hose to injector; 5 – suction line filter; 6 – pump; 7 – reduction valve; 8 – self-cleaning pressure line filter; 9 – beam sections' control valves; 10 – manometer; 11 – beam section with nozzles; 12 – tap to adjust the intensity of liquid mixing; 13 – injector; 14 – injector control tap; 15 – tank to dissolve the powdered products; 16 – taps; 17 – nozzles located in the arch form; 18 – rotating nozzle; 19 – tap for turning the tank on and off; 20 – rotating tank wash nozzle; 21 – strainer; 22 – filler hole lid; 23 – remote-control box (spraying computer); 24 – clean water tank; 25 and 26 – a storage place; 27 – filling line tap; 28 – tap to turn the washing brush on and off ; 29 – drum for collection of washing hose; 30 – brush for washing the sprayer exterior; 31 – liquid level scale; 32 – filling hose connector to connect to the hydrant; 33 – hydraulic blender; 34

*Suspended field tractor-mounted hydraulic sprayers* are mounted on the rear hydraulic lift of a tractor, and their entire weight during operation and transportation falls on the tractor wheels (Figure 2). Their tank capacity ranges from 300 to

1 2

Suspended field tractor-mounted hydraulic sprayers are mounted on the rear hydraulic lift of a tractor, and their entire weight during operation and transportation falls on the tractor wheels (Figure 2). Their tank capacity ranges from 300 to 1800 l, and operational width ranges from 6

6 3 5

1

13

22 4

31 21

9

24 Weed Biology and Control

23 25

to 24 m.

Suspended field tractor-mounted hydraulic sprayers do not have a chassis. When choosing a suspended field hydraulic sprayer, the following factors should be noted:


The entire weight of the suspended tractor-mounted hydraulic sprayer during operation and transportation falls on its chassis wheels (Figure 3). The modern suspended tractor-mounted hydraulic sprayers meet almost all the requirements of professional users. Their tank capacity ranges from 1,500 to 6,000 l. Larger-capacity tanks increase productivity, but also have some drawbacks: the soil is more burdened, and there is a lack of stability when spraying in hilly areas or on public roads if the speed rises to 50 km h-1 . Depending on the tank capacity, the working width of the suspended sprayers is usually between 12 and 36 m; however, there are manufacturers offering 48 m working width beams.

<sup>1 –</sup> support; 2 – drawbar with eye; 3 – hydraulic hoses; 4 – clean water tank; 5 – ladders; 6 – clean water tank; 7 – tank; 8 – beam sections; 9 – nozzles; 10 – circle; 11 – carriage; 12 – preparations tank; 13 – taps; 14 – pump [1].

**Figure 3.** Suspended tractor-mounted hydraulic sprayer

When choosing a suspended tractor-mounted hydraulic field sprayer, the following factors should be noted:


**•** Whether pump performance matches the working width of the sprayer - remember that injection pneumohydraulic nozzles with a long body require higher operational pressure; **•** The view of the sprayer, i.e., whether there are marks of corrosion, the state of the painted

The entire weight of the suspended tractor-mounted hydraulic sprayer during operation and transportation falls on its chassis wheels (Figure 3). The modern suspended tractor-mounted hydraulic sprayers meet almost all the requirements of professional users. Their tank capacity ranges from 1,500 to 6,000 l. Larger-capacity tanks increase productivity, but also have some drawbacks: the soil is more burdened, and there is a lack of stability when spraying in hilly

working width of the suspended sprayers is usually between 12 and 36 m; however, there are

5 6 7 8

2 1 14 13 12 11 10

8 – beam sections; 9 – nozzles; 10 – circle; 11 – carriage; 12 – preparations tank; 13 – taps; 14 – pump [1].

1 – support; 2 – drawbar with eye; 3 – hydraulic hoses; 4 – clean water tank; 5 – ladders; 6 – clean water tank; 7 – tank;

When choosing a suspended tractor-mounted hydraulic field sprayer, the following factors

**•** What the sprayer clearance is, i.e., it should not be less than 0.6 m, and preferably from 0.7 to 0.8 m. It should not be greater than the tractor clearance. The lower the sprayer tank is

**•** Whether a tank of more than 3000 l has intermediate walls to suppress liquid splashing;

. Depending on the tank capacity, the

surfaces and the quality of welds.

26 Weed Biology and Control

3

**Figure 3.** Suspended tractor-mounted hydraulic sprayer

attached, *the more stable the* machine is;

should be noted:

4

areas or on public roads if the speed rises to 50 km h-1

manufacturers offering 48 m working width beams.


It has been estimated that suspended hydraulic sprayers are worth buying if the size of a farm is 150-200 ha. Furthermore, in larger farms (more than 1000 ha), the maintenance costs of suspended sprayers are lower than those of self-propelled or put-on sprayers [2].

Put-on tractor-mounted hydraulic field sprayers are installed on certain types of tractor or selfpropelled chassis (e.g., MB-Trac, Unimog, JSB-Fastrac and Fendt-Xylon). The capacity of such sprayers is up to 3.000 l. It is limited by the tire load capacity and maximum permissible axle load. Put-on sprayers are much more manoeuvrable than suspended ones; however, their preparation time for operation is much longer. A fairly high performance is ensured by a beam of 27 m operational width. When choosing a hydraulic put-on sprayer, the following factors should be noted:

**•** Where the centre of gravity of the spray unit is. It should be a little further than rear axle force of the machine (i.e., the tractor or self-propelled chassis), and the spray beam should also be as close to the power machine as possible;


Requirements for sprayer tanks [3]:


The pump draws solution from the tank and supplies it to distribution pipe with nozzles. It should ensure the desired smooth solution flow rate and constant working pressure, and the flow needed for the hydraulic blender.

The required pump capacity of a tractor or self-propelled hydraulic field sprayer, for the normal course of solution spray rate (up to 600 l ha-1) and maximum allowable operating speed (up to 10 km h-1), is calculated as follows: under 5-10 l min-1 for each working metre wide, 10 % of the tank capacity for solution mixture is added if the pressure is 5 bar [3].

Pump capacity of a tractor or self-propelled pneumohydraulic field or garden sprayer: under 10-15 l min-1 , 10 % of the tank capacity for solution mixture is added if the pressure is 30 bar [3]. If the existing pump capacity is 15 % less than required, the pump is out of order. Sub‐ stantial reduction in pump performance worsens the quality of mixing.

Piston pump consists of a frame with a crankshaft on which connecting rods lift the pistons. Pistons slide in cylinders; there is a box with suction and pressure valves and a pressure equalization device over them. Advantages: durable, high pressure range, less wear and tear than with diaphragm pumps; if increasing the pressure, performance is almost unchanged; only a small piston surface area comes into contact with harmful solutions. Disadvantages: expensive, heavy, bulky; cannot be put on the tractor power supply shaft; when spraying suspensions or when there is sand in the water, pistons and cylinders wear out; idling can damage the pistons.

The main part of a membrane or a piston-diaphragm pump is a membrane which changes the size of the chamber due to its movement. The membrane is made convex by a cam or crank mechanism. Advantages: low weight, low wear, and low cost of maintenance and repair work; may work in idle mode for some time; large pressure range; when increasing operating pressure, performance decreases insignificantly; any formulation may be sprayed with it, since all moving parts are enclosed in a frame and are not in contact with the spray solution. Membrane or piston-diaphragm pump disadvantages: due to their large area, membranes are heavily exposed to mechanical and chemical effects; pump durability largely depends on membrane quality.

In a pinion pump, solution is pumped by two rotating pinions in a frame. On one side of the frame, there is suction, on another, pressure holes. Advantages: inexpensive, lightweight, no need for suction and pressure valves, easy to maintain. Disadvantages: pistons wear heavily if suspensions are sprayed or pollutants get on them; increasing pressure significantly reduces productivity; water quality is essential; not permitted to spray copper-containing products; dangerous to work in idle mode.

Pressure pulsation smoothing devices are required for all piston, membrane and pistonmembrane pumps. They are installed in the suction and pressure lines and made of two plastic or metal frames with membranes between them. The device installed in the suction line consists of a plastic frame and a rubber membrane. On the top of the valve the membrane is inflated. Air pressure is indicated in the pump manually. It depends on the spray pressure. When working pressure is 1.5-3 bar, the recommended air pressure in the pulsation smoothing device should be 0-1 bar; when pressure is 3-15 bar, air pressure should be 1-3 bar, and when working with 15-25 bar working pressure, it should be up to 3-4 bar.

A mixer is installed inside the sprayer tank and mixes the toxic solution so that during work the concentration should be the constant. Mixers may be mechanical*, hydraulic* or pneumatic. Mechanical mixers may be bladed or disc type. In hydraulic mixers, the solution gets into the tank through the mixing tube, through injection mixing nozzles or through tube and injection nozzles. Hydraulic mixers are designed so that most of the required flow for solution mixing is sucked through the holes on the injection mixing nozzle. Four litres per minute flow per 100 l tank capacity is needed to stir the solution, while 6 l min-1 flow is needed for emulsions, and as much as 8 l min-1 for suspensions [3].

In the operation process of a control panel operated sprayer, the usual equipment of the control panel is:


**•** Whether spray units can be mounted on the machine and removed from it quickly;

filled with liquid mineral fertilizers (e.g., urea-ammonium nitrate solution);

**•** Whether the tractor's hydraulic system is cooled sufficiently.

**•** Smooth surface, rounded edges, resistant to corrosion, easily washed;

**•** Sloping bottom with a solution drain tap and deep drip pan to collect it;

along a water carrier to the field;

28 Weed Biology and Control

rotated by the hydraulic engine;

Requirements for sprayer tanks [3]:

**•** Removable, deep filler strainer;

**•** 5 % reserve capacity of the reservoir;

flow needed for the hydraulic blender.

10-15 l min-1

damage the pistons.

**•** Solution level scale interval – 50 l (prominent);

**•** Rotating tank cleaning nozzle for tank washing.

(up to 10 km h-1), is calculated as follows: under 5-10 l min-1

**•** Whether or not the sprayer is blocked by the coupling parts, since it is convenient to take

**•** Whether or not the permissible total weight of the tractor exceeds the weight of a sprayer

**•** Whether there are enough hydraulic connections on the tractor in case the sprayer pump is

**•** Minimum filler diameter – 200 mm (up to capacity of 600 l) or 300 mm (> 600 l capacity);

The pump draws solution from the tank and supplies it to distribution pipe with nozzles. It should ensure the desired smooth solution flow rate and constant working pressure, and the

The required pump capacity of a tractor or self-propelled hydraulic field sprayer, for the normal course of solution spray rate (up to 600 l ha-1) and maximum allowable operating speed

Pump capacity of a tractor or self-propelled pneumohydraulic field or garden sprayer: under

[3]. If the existing pump capacity is 15 % less than required, the pump is out of order. Sub‐

Piston pump consists of a frame with a crankshaft on which connecting rods lift the pistons. Pistons slide in cylinders; there is a box with suction and pressure valves and a pressure equalization device over them. Advantages: durable, high pressure range, less wear and tear than with diaphragm pumps; if increasing the pressure, performance is almost unchanged; only a small piston surface area comes into contact with harmful solutions. Disadvantages: expensive, heavy, bulky; cannot be put on the tractor power supply shaft; when spraying suspensions or when there is sand in the water, pistons and cylinders wear out; idling can

, 10 % of the tank capacity for solution mixture is added if the pressure is 30 bar

% of the tank capacity for solution mixture is added if the pressure is 5 bar [3].

stantial reduction in pump performance worsens the quality of mixing.

for each working metre wide, 10


Pressure in sprayers is adjusted by reducing valve*s*. The reducing valve may be closed by an adjustable spring; in this case, pressure depends on tightening the valve springs. When the reduction valve is closed by a screw reducing the hole through which the solution returns to the reservoir, the pressure depends on the opening degree of the hole.

Working width of the sprayer is narrowed by closing the *control valves of* sections. If sprayer sections are turned off, pressure equalization devices maintain constant pressure since the solution is returned to the tank. Having changed the nozzles, the pressure equalization device should be adjusted.

The tractor driver, when working, has to reach the central closing tap, which is controlled by hand, the section taps and the reduction valve; he should also be able to see the gauge very well. This is very comfortable and efficient to control them from the tractor cabin by *electro‐ magnetic valves.* The most important factors conditioning the spraying of a solution to a hectare are precise and even operational speed, and the spraying norm. It is very important for every user to measure precisely these two indices. There are various devices for measuring driving speed and solution spraying norm.

*Spraying computers* measure both mentioned indices and maintain the necessary levels. They operate as follows: the desired solution norm is entered into the microprocessor (l ha-1). A radar sensor measures driving speed and sends data to the processor, which calculates the required spraying pressure to maintain the desired solution spraying norm. A flow meter measures the amount of the sprayed solution (l min-1) and delivers the data to the processor. The latter compares the present and desired meanings, and sends the necessary control commands to a regulator.

*Filters* clean solution from small admixtures and secure the sprayer pump against quick wear-out, and the nozzles and sprayers against jamming. The following filters may be present in sprayers: filling-in hole, pump line, centre pressure line, distribution pipe sec‐ tions and nozzles. It is easier to use the sprayer if one additionally equips distribution pipe sections with filters. Such a filter is made of a frame and equipped with a sieve or plate with 0.1–0.7 mm cells (100–25 cells per inch). It is advisable to choose smaller filters for sections than those for sprayers.

The self-cleaning pressure line filter is made of two plastic frame parts, a sieve, a flow directing stack and a damper. Liquid is supplied from the pump to filter through the pressure line. The stack increases flow speed and directs it to the sieve walls. Cleaned liquid is supplied through the pressure line to the control panel, and admixtures and unmelted preparation particles return to the tank through the damper by the return line. Damper size (from 3 to 6 mm) is chosen according to the model of the pump, the highest operational pressure and highest productivity of all sprayers. If the filter is polluted, solution may return to the tank through the secure valve by the return line.

Sprayer filters may be in cylinder, trapezium or half-circle form; they may be cleft or net. Disadvantages of net, half-circle form filters are as follows: they cannot be used with the hydraulic carrying away of small droplets or injection pneumohydraulic sprayers. Net sprayer filters are made of brass, aluminium or stainless steel, and cleft – from plastic.

The central pressure line filters should be the smallest; the cell size should be smaller than the area of the cross-section of the used nozzles. The water filling pipe's filter is the biggest. The cell size is up to 20 mm. The cell size of the preparation tank filter is up to 1 mm, and the cell size of the filling hole's sieve is from 0.5 to 2 mm. The recommended number of cells for the various filters is presented in Table 2.


**Table 2.** Recommended number of cells for various filters per inch [3].

reduction valve is closed by a screw reducing the hole through which the solution returns to

Working width of the sprayer is narrowed by closing the *control valves of* sections. If sprayer sections are turned off, pressure equalization devices maintain constant pressure since the solution is returned to the tank. Having changed the nozzles, the pressure equalization device

The tractor driver, when working, has to reach the central closing tap, which is controlled by hand, the section taps and the reduction valve; he should also be able to see the gauge very well. This is very comfortable and efficient to control them from the tractor cabin by *electro‐ magnetic valves.* The most important factors conditioning the spraying of a solution to a hectare are precise and even operational speed, and the spraying norm. It is very important for every user to measure precisely these two indices. There are various devices for measuring driving

*Spraying computers* measure both mentioned indices and maintain the necessary levels. They operate as follows: the desired solution norm is entered into the microprocessor (l ha-1). A radar sensor measures driving speed and sends data to the processor, which calculates the required spraying pressure to maintain the desired solution spraying norm. A flow meter measures the amount of the sprayed solution (l min-1) and delivers the data to the processor. The latter compares the present and desired meanings, and sends the necessary control commands to a

*Filters* clean solution from small admixtures and secure the sprayer pump against quick wear-out, and the nozzles and sprayers against jamming. The following filters may be present in sprayers: filling-in hole, pump line, centre pressure line, distribution pipe sec‐ tions and nozzles. It is easier to use the sprayer if one additionally equips distribution pipe sections with filters. Such a filter is made of a frame and equipped with a sieve or plate with 0.1–0.7 mm cells (100–25 cells per inch). It is advisable to choose smaller filters

The self-cleaning pressure line filter is made of two plastic frame parts, a sieve, a flow directing stack and a damper. Liquid is supplied from the pump to filter through the pressure line. The stack increases flow speed and directs it to the sieve walls. Cleaned liquid is supplied through the pressure line to the control panel, and admixtures and unmelted preparation particles return to the tank through the damper by the return line. Damper size (from 3 to 6 mm) is chosen according to the model of the pump, the highest operational pressure and highest productivity of all sprayers. If the filter is polluted, solution may return to the tank through

Sprayer filters may be in cylinder, trapezium or half-circle form; they may be cleft or net. Disadvantages of net, half-circle form filters are as follows: they cannot be used with the hydraulic carrying away of small droplets or injection pneumohydraulic sprayers. Net sprayer

filters are made of brass, aluminium or stainless steel, and cleft – from plastic.

the reservoir, the pressure depends on the opening degree of the hole.

should be adjusted.

30 Weed Biology and Control

regulator.

speed and solution spraying norm.

for sections than those for sprayers.

the secure valve by the return line.

The purpose of the *sprayer beam* is, during operation, to hold the nozzles parallel to the sprayed surface so that the sprayed solution is distributed evenly. The beam may be metal or plastic, made of several 3-4 mm wide parts connected by joints. Maximum length of the sprayer beam is 6 m [4].

Nozzles are fastened on a sprayer beam or distribution pipe with iron rings 0.5 m apart, one by one, or on heads in threes or fours with various sized holes. In this case, when wishing to change the nozzles and spraying norm, it is sufficient to turn the heads one-third or one-quarter of the circle, and turn on the other nozzles. If the real distance between the nozzles is not 0.5 m, the indicated norm of the sprayed liquid should be multiplied by a certain coefficient: e.g., coefficient 2.5 if the real distance between nozzles is 0.2 m, and likewise 2 (0.25 m), 1.67 (0.3 m), 1.43 (0.35 m), 1.25 (0.4 m), 1.11 (0.45 m), 0.91 (0.55 m), 0.83 (0.6 m) and 0.66 (0.75 m).

Cleft flat-flow nozzles on a hydraulic field sprayer beam should be mounted so that flows sprayed by separate nozzles would cover each other two or three times [5-7]. In order that liquid flows of adjacent nozzles do not interfere with each other, holes of cleft flat-flow nozzles should be turned at 7.5–10° angles in respect of the beam. In older nozzle frames (where nozzles are fastened by screws), this angle is determined by a special key; in new frames with quickjoint screws, nozzles are put into the necessary angle automatically.

Depending on the height of the sprayed plants, the beam may be lifted by one or two hydraulic cylinders or a line winch. There should be the possibility to change the height of the sprayer beam to the sprayed surface from 0.40 to 2 m. The distance of the cleft flatflow nozzles to the sprayed surface depends on the spraying angle. Thus, using spraying nozzles of 110° or 120°, the optimal distance to the sprayed surface is 0.50 m. It is very important to determine precisely the spraying height, since, if one lifts the sprayer beam 0.10 m higher, *twice as many* drops may drift downwind. If the sprayer beam is wider than 18 m, the optimal spraying height is 0.75 m. In this case, using cleft flat-flow nozzles with an 80° angle, a double interference of flows is created; indeed, when spraying with 110– 120° angle nozzles, a triple interference is obtained [6, 8].

In order for the beam not to swing while working in an uneven field, it is held by swing damp devices.

Lengthwise distribution of the sprayed solution mostly depends on the horizontal swinging of the sprayer beam, the driving speed and the field's evenness. Operational width sprayer beams longer than 12 m should be equipped with swinging damp devices and hang freely. In a hilly locality, it is advisable to use a sprayer with a beam position fixation mechanism.

Even distribution of protection preparations mostly depends on *nozzles.*They are also classified into a number of sorts:


Cleft flat-flow and injection nozzles may be of *symmetric* and *asymmetric stream*. Symmetric flow cleft flat-flow and injection nozzles may also be classified into *one-flow* and *two-flow*, and asymmetric into to *short-stream* and *long-stream*. One-symmetric-stream cleft flat-flow nozzles may be *standard*, *universal* and *with dispenser* (fewer drops drift downwind). One-symmetricstream injection nozzles may be *compound* and *compact.* Compact and injection nozzles may be of *low* and *high pressure.*

Stream nozzles may be *one-hole* and *multi-hole*. Multi-hole stream nozzles may be of *three*, *five*, *six* and *eight holes.*

Cone-stream nozzles may be standard and injection, of double or hollow cone-stream.

Often, the entire junction is called a nozzle; in this case, a nozzle is made of a frame with momentum closing valve, filter, tip and quick connection nut. The cleft sprayer nozzle is ceramic, steel, plastic or brass bushing with cleft pressed into a coloured frame. It is advisable to choose the material for bushing depending on usage sphere and volume.

nozzles of 110° or 120°, the optimal distance to the sprayed surface is 0.50 m. It is very important to determine precisely the spraying height, since, if one lifts the sprayer beam 0.10 m higher, *twice as many* drops may drift downwind. If the sprayer beam is wider than 18 m, the optimal spraying height is 0.75 m. In this case, using cleft flat-flow nozzles with an 80° angle, a double interference of flows is created; indeed, when spraying with 110–

In order for the beam not to swing while working in an uneven field, it is held by swing damp

Lengthwise distribution of the sprayed solution mostly depends on the horizontal swinging of the sprayer beam, the driving speed and the field's evenness. Operational width sprayer beams longer than 12 m should be equipped with swinging damp devices and hang freely. In a hilly locality, it is advisable to use a sprayer with a beam position fixation mechanism.

Even distribution of protection preparations mostly depends on *nozzles.*They are also classified

**•** According to operational mode, nozzles are classified into *hydraulic, pneumohydraulic* and

**•** According to the form of the sprayed liquid, hydraulic nozzles are classified into *flat-flow,*

**•** According to construction, rotational nozzles are classified into *disc* and *drum,* and pneu‐

**•** According to purpose, flat-flow nozzles are classified into *continuous*, *band spraying* and

Cleft flat-flow and injection nozzles may be of *symmetric* and *asymmetric stream*. Symmetric flow cleft flat-flow and injection nozzles may also be classified into *one-flow* and *two-flow*, and asymmetric into to *short-stream* and *long-stream*. One-symmetric-stream cleft flat-flow nozzles may be *standard*, *universal* and *with dispenser* (fewer drops drift downwind). One-symmetricstream injection nozzles may be *compound* and *compact.* Compact and injection nozzles may be

Stream nozzles may be *one-hole* and *multi-hole*. Multi-hole stream nozzles may be of *three*, *five*,

Often, the entire junction is called a nozzle; in this case, a nozzle is made of a frame with momentum closing valve, filter, tip and quick connection nut. The cleft sprayer nozzle is

Cone-stream nozzles may be standard and injection, of double or hollow cone-stream.

*cone-flow* and *cone-stream,* and pneumohydraulic into *flat-flow* and *cone-flow*;

**•** According to construction, flat-flow nozzles are classified into *cleft* and *deflector*;

**•** According to spraying angle: 25, 40, 60, 65, 80, 90, 110, 120, 130, 150°;

**•** According to productivity: 01, 015, 02, 025, 03, 04, 05, 06, 08, 09.

120° angle nozzles, a triple interference is obtained [6, 8].

devices.

32 Weed Biology and Control

into a number of sorts:

mohydraulic into *pressure* and *injection*;

*rotational*;

*washing*;

of *low* and *high pressure.*

*six* and *eight holes.*

The colour of a nozzle tip and nut indicates the size of a cleft: orange – 01, green – 015, yellow – 02, violet – 025, blue – 03, red – 04, brown – 05, grey – 06, white – 08. The tips are marked according to ISO standard. For instance, *LU 120 – 04S* means: LU – type of a nozzle, in this case – Lechler universal; 120 – nozzle angle, 03 – nozzle productivity, in this case – 0.3 American gallons per minute if the pressure is 40 psi (1 American gallon = 3.7854 l, and 1 psi = 0.0703 bar, in this case 1.136 l min-1, if pressure is 2.81 bar); S – bushing made of special stainless steel (letter "C" means that the bushing is ceramic).

*Standard or universal cleft flat-flow nozzles* are widely used and are inexpensive. When chang‐ ing pressure, solution may be sprayed in small, average or large drops. It is possible to spray in windyweatherwithwindspeedupto3ms-1.Solutionisdosedandsprayedthroughthe cleft[9].

*Cleft flat-flow nozzles for band spraying* (Figure 4 a and b), due to a special construction, evenly distribute solution drops in the sprayed area; therefore, they spray qualitatively with a pressure of 1 bar. Having duly chosen the spraying height, it is possible to spray very wide (10–25 cm width) stripes. These nozzles are used for field sprayers or mounted on sowing and rowing cultivators. Due to the exact flow limitations, the loss of plant protection preparation is minimal.

*In cleft small-drop blow nozzles*, there is an additional primary nozzle (dispenser) that forms a flat stream. In this case, the quantity of unwanted small drops which may be blown downwind or steamed is reduced. Drops of the sprayed solution are blown downwind five times less than usual; it is possible to work if the wind speed is up to 5 m s-1. In the primary nozzle (dispenser), when the area of the cross-section of a hole is smaller than the cleft area of the nozzle, it reduces pressure a little; the solution is sprayed in larger drops, and the main cleft of the nozzle wears less. Apart from that, it may be up to 50 % larger than that of the usual cleft nozzles, so it clogs rarely. Nozzles of this type may be fastened not only in the hydraulic field, but also in all pneumohydraulic garden sprayers. The biological effectiveness of plants sprayed by protec‐ tive products is the same as when sprayed with small drops; however, the sprayed surface is covered evenly, and with the low operational pressure fewer drops are blown downwind. Due to the flat flow, the air stream supply is optimal, and with the higher pressure, the liquid is sprayed by small drops [2]. The company Agrotop was the first to create this type of nozzle, the SD-Servodrop. Later on, similar nozzles were offered by other producers: AD-antidrift (Lechler), LO-drift (Lurmark), ADI (Desmarquest), and DG-drift guard (TeeJet Technical). The special advantage of such nozzles is the possibility to spray smaller liquid amounts in larger drops, i.e., 100–150l ha-1 [10, 11].

*Two-stream cleft nozzle* is a special nozzle for spraying small drops. A double flat-stream is sprayed in the driving direction at 30° forwards and back. When working, good coverage of vertical surfaces is achieved (e.g., stem, eras). *Two-stream nozzles for band spraying* are mostly suitable for spraying of herbicides, fungicides and insecticides in crops with abundant foliage (Figure 4 c),. They are ideal for spraying between rows and rows of plants. TwinJet™ twostream nozzles spraying at 40° angles should be set at the height of 25 cm for spraying a 20 cm wide stripe (80° spraying angle, 13 cm high); for a 25 cm wide stripe, at the height of 30 cm (80°, 15 cm high), and for a 30 cm wide stripe, at a height of 36 cm (80°, 18 cm).

*a* – cleft flat-flow Lechler ES; *b* – cleft flat-flow TeeJet® E-type; *c* – two-stream TwinJet™ E-type; *d* – fastening scheme on sprayer beam: A – width between rows, B – area of the sprayed stripe, H – spraying height [7, 9].

**Figure 4.** Nozzles for band pesticide spraying

*TwinSprayCap quick switch-on holders* have been created aiming to capture both the advantages of injection pneumohydraulic nozzles, reducing downwind flow of the sprayed drops, and those of two-stream spraying, which ensures better coverage of the sprayed surfaces. The holder is made of two parts. It is easily disassembled by pulling out a fixation, and it is suitable for all nozzles with an external diameter of 8 or 10 mm. Double flat-flow is sprayed with the driving direction of 30° forward and back. Aiming to achieve optimal transverse distribution of the sprayed liquid, the nozzle position is fixed automatically. Usage field:


*Deflector flat-flow sprayer* involves a ceramic or plastic tube on one end, which ends with a cut and shield: a deflector. Its spraying angle is up to 140°; it is rarely blocked. Spraying with the pressure of 1–2 bars, few drops are blown downwind. The nozzle is especially suitable for spraying soil herbicides. It is also advisable to use it in tubes spraying liquid mineral fertilizers. Separation of liquid dosage and spraying in deflector nozzles helps to spray the liquid in larger drops. In the deflector nozzles Turbo-FloodJet™ and Turbo-TeeJet™ produced by the com‐ pany TeeJet Technical, liquid is directed to a deflector that is turned by a small angle (about 15° of the vertical) and is very evenly sprayed in a wide and flat stream [12]. These nozzles, especially with an operational pressure of 2–3 bars, spray in larger drops than other flat-flow nozzles [12, 13].

*Cleft asymmetric stream nozzles* may be hydraulic (e.g., Lechler OC) and pneumohydraulic (e.g., Lechler IS). In hydraulic asymmetric stream nozzles, the cleft is on the side, and the liquid is sprayed at an angle of 90º. They are produced of brass or stainless steel. The recommended operational pressure is 1.5–2.5 bar. According to the width of the sprayed area, these nozzles are classified into short-stream and long-stream. The width of the sprayed flow of shortstream nozzles may vary from 1.2 to 2.5 m; and that of the long-stream may reach as much as 6–8 m. The width of the sprayed flow depends on the nozzle set angle, which may vary from 25 to 45º.

Short-stream asymmetric flow nozzles may be used:

wide stripe (80° spraying angle, 13 cm high); for a 25 cm wide stripe, at the height of 30 cm

*a* – cleft flat-flow Lechler ES; *b* – cleft flat-flow TeeJet® E-type; *c* – two-stream TwinJet™ E-type; *d* – fastening scheme on

*TwinSprayCap quick switch-on holders* have been created aiming to capture both the advantages of injection pneumohydraulic nozzles, reducing downwind flow of the sprayed drops, and those of two-stream spraying, which ensures better coverage of the sprayed surfaces. The holder is made of two parts. It is easily disassembled by pulling out a fixation, and it is suitable for all nozzles with an external diameter of 8 or 10 mm. Double flat-flow is sprayed with the driving direction of 30° forward and back. Aiming to achieve optimal transverse distribution

**•** Especially suitable for spraying contact, (partly) systematic plant protection preparations;

*Deflector flat-flow sprayer* involves a ceramic or plastic tube on one end, which ends with a cut and shield: a deflector. Its spraying angle is up to 140°; it is rarely blocked. Spraying with the pressure of 1–2 bars, few drops are blown downwind. The nozzle is especially suitable for spraying soil herbicides. It is also advisable to use it in tubes spraying liquid mineral fertilizers.

sprayer beam: A – width between rows, B – area of the sprayed stripe, H – spraying height [7, 9].

of the sprayed liquid, the nozzle position is fixed automatically. Usage field:

**Figure 4.** Nozzles for band pesticide spraying

**•** For spraying corn ears;

**•** For destruction of weeds;

**•** For band spraying.

**•** In gardening;

34 Weed Biology and Control

(80°, 15 cm high), and for a 30 cm wide stripe, at a height of 36 cm (80°, 18 cm).


*Long-stream asymmetric flow nozzles* are used for overhead irrigation and irrigation of riding halls. They are fastened at the ends of the beam. Liquid is supplied to the nozzles by separate or already existing pipe-lines forming T-form branches. It is important that a sprayer should obtain a pump of a sufficient productivity, since two long-stream nozzles need an additional flow of about 80 l min-1.

*Hydraulic cone-stream nozzles* may be full cone-flow and hollow cone-flow. In hollow cone-flow, due to a special insert, liquid flow starts to turn and flows in the borders of the hole. The insert may be a cylinder with slantwise cut or a plate with slantwise holes or slantwise surfaces.

Cone-flow nozzles are often used in pneumohydraulic garden sprayers. Their spraying angle may be from 20° to 120° (usually 65° or 80°). Cone-flow nozzles spray liquid in smaller drops than flat-flow nozzles, and their size spectrum is narrower. However, slantwise liquid distribution (that is measured by a special stand with gutters) by cone-flow nozzles mounted on a hydraulic field sprayer beam is worse.

Operational pressure of cone-flow nozzles is between 3 and 20 bar [7, 9].

Even though marking of cone-flow nozzles is not standardized, a number of producers use the same colours as in flat-flow nozzles. Some producers of cone-flow nozzles indicate the diameter (in mm) of dosage plate holes and liquid flow holes.

*Pneumohydraulic nozzles* used for field sprayers were created more than 25 years ago. The aim was to reduce water and expenditure of plant protection products downwind.

<sup>1 –</sup> distribution pipe; 2 – moment closing valve; 3 – liquid channel; 4 – liquid dispenser; 5 – plate; 6 – flow of sprayed liquid; 7 – deflector tip; 8 – branch; 9 – mixing camera; 10 – tip for connection of air hose; top left – range of the sprayed drops (bubbles); bottom left – view of the sprayer mounted on the beam with dispensers of various size [1].

**Figure 5.** Pressure pneumohydraulic nozzle by Airtec

*In pressure pneumohydraulic nozzles* the liquid and air mix are supplied by separate channels and are sprayed with higher speed, so that smaller drops are not blown downwind.

*In injector pneumohydraulic nozzles,* the air taken in from the side holes mixes with the liquid and is sprayed by larger air-filled drops which are also blown less downwind.

Airtec pressure pneumohydraulic nozzles were created in the middle of the 1980s by the company Cleanacres (United Kingdom). In this nozzle, liquid passing through the dispenser (hole diameter 0.9 mm) is firstly sprayed on a plate in the mixing camera. Suppressed air is supplied to a mixing camera from a compressor by a separate line (Figure 5).

One nozzle requires about 60–70 l min-1 of air. In a mixing camera, some of the drops are filled with air, i.e., bubbles are formed. This mixture of air and liquid is sprayed through the deflector nozzle. The size of the sprayed drops (bubbles) is regulated by changing the liquid and air ratio. The higher the pressure, the smaller the drops (bubbles). Air flow gives higher initial speed to the drops (bubbles) of the sprayed drops (bubbles), so they may get deeper into the foliage. Due to complicated nozzle construction, there are few drops (bubbles) smaller than 100 µm or larger than 400 µm. The solution is sprayed by drops (bubbles) of the same size; so, more solution is usefully used (70 – 140 l of water to one hectare is enough). The composition of the pneumohydraulic nozzle AirJet produced by the company TeeJet Technical is very similar. Liquid pressure in it may be regulated from 0.7 to 4.0 bar, and air pressure from 0.3 to 2.0 bar. From 12 to 60 l min-1 of air may be supplied to one nozzle. Depending on the dosage plates used and air and liquid pressure, it is possible to spray up to one hectare from 10 to 240 l (if driving speed is 6 km h-1). The diameter of dosage plate holes may vary between 0.78, 0.89 and 1.06 mm. Changing the air pressure, the liquid may be sprayed by very small or very large drops. Productivity of pneumohydraulic nozzles depends on air pressure. If liquid pressure is equal, increasing air pressure productivity of the nozzle reduces. With increasing air pressure, the range of the sprayed drops changes, i.e., they become smaller. Thus, using pressure pneumohydraulic nozzles, it is harder to set the norm of the sprayed liquid [2].

ThepressurepneumohydraulicnozzleEurofoilcreatedbytheDanishcompanyDanfoilismeant for field sprayers. In this nozzle, liquid from the side is supplied to a plastic plate of stream‐ line form which is located in the middle of the rubber air nozzle (Figure 6). Air flow supplied from the top disperses the liquid in small drops which are sprayed with a high speed through the wide air nozzle hole, so only a few drops may be blown downwind. Liquid is dosed by a plate with a 0.7 mm diameter hole. Liquid and air mix swirls, so vertical surfaces are covered very well, as well as upper and lower sides of leaves. With these nozzles, up to a hectare may be sprayed from 20 to 100 l liquid. The size range of drops sprayed by Eurofoil nozzle is very wide: from the smallest 100 µm to 800 µm. The size of the sprayed drops may be regulated by changing the quantity of the air supplied to a nozzle. Even if in this case there are more drops smaller than 100 or 200 µm than when spraying by the usual flat-flow hydraulic nozzle, e.g., XR110-04, due to higher movement speed,fewer drops are still blown downwind. The optimal spraying height of Eurofoil pressure pneumohydraulic nozzles is 0.6–0.7 m, and the recom‐ mended driving speed of the spraying machine varies from 4 to 8 km h-1. Smaller drops cover the sprayed surfaces better; so using Eurofoil pressure pneumohydraulic nozzles, the norms of plant protection products and liquid mineral fertilizers may be reduced to 50 % [1].

The first confidently operating complex injector pneumohydraulic nozzle, TurboDrop®, was created by the company Agrotop in the beginning of the 1990s. A little later, the company Lechler created a simpler, compact injector pneumohydraulic nozzle. Later on, similar nozzles started to be produced by the companies TeeJet Technical, BfS (Billericay Farm Services Ltd.), Agrotop and Hardi.

**Figure 6.** Eurofoil pressure pneumohydraulic nozzle: 1 – rubber air nozzle, 2 – plate [1].

*In pressure pneumohydraulic nozzles* the liquid and air mix are supplied by separate channels

1 – distribution pipe; 2 – moment closing valve; 3 – liquid channel; 4 – liquid dispenser; 5 – plate; 6 – flow of sprayed liquid; 7 – deflector tip; 8 – branch; 9 – mixing camera; 10 – tip for connection of air hose; top left – range of the sprayed

6 7

8

9 10

*In injector pneumohydraulic nozzles,* the air taken in from the side holes mixes with the liquid

Airtec pressure pneumohydraulic nozzles were created in the middle of the 1980s by the company Cleanacres (United Kingdom). In this nozzle, liquid passing through the dispenser (hole diameter 0.9 mm) is firstly sprayed on a plate in the mixing camera. Suppressed air is

One nozzle requires about 60–70 l min-1 of air. In a mixing camera, some of the drops are filled with air, i.e., bubbles are formed. This mixture of air and liquid is sprayed through the deflector nozzle. The size of the sprayed drops (bubbles) is regulated by changing the liquid and air ratio. The higher the pressure, the smaller the drops (bubbles). Air flow gives higher initial speed to the drops (bubbles) of the sprayed drops (bubbles), so they may get deeper into the foliage. Due to complicated nozzle construction, there are few drops (bubbles) smaller than 100 µm or larger than 400 µm. The solution is sprayed by drops (bubbles) of the same size; so, more solution is usefully used (70 – 140 l of water to one hectare is enough). The composition of the pneumohydraulic nozzle AirJet produced by the company TeeJet Technical is very similar. Liquid pressure in it may be regulated from 0.7 to 4.0 bar, and air pressure from 0.3 to 2.0 bar. From 12 to 60 l min-1 of air may be supplied to one nozzle. Depending on the dosage plates used and air and liquid pressure, it is possible to spray up to one hectare from 10 to 240 l (if driving speed is 6 km h-1). The diameter of dosage plate holes may vary between 0.78, 0.89

and are sprayed with higher speed, so that smaller drops are not blown downwind.

drops (bubbles); bottom left – view of the sprayer mounted on the beam with dispensers of various size [1].

5

4

and is sprayed by larger air-filled drops which are also blown less downwind.

3

2

**Figure 5.** Pressure pneumohydraulic nozzle by Airtec

1

36 Weed Biology and Control

supplied to a mixing camera from a compressor by a separate line (Figure 5).

*A complex injector pneumohydraulic nozzle called TurboDrop®* (Figure 7) is made of an adaptor, quick connection nut, dosage plate, injector, mixing and pulsing damp camera, rubber tight and tip. Using the adaptor, it is possible to connect these two nozzles to any quick connection nuts 1. Round flow is sprayed to injector 8 through dosage plate 3. Air is pumped through holes present on injector sides. Air and liquid are mixed in camera 4. Liquid swirl is reduced in the widest zone of the mixing camera, and pulsing is damped in ring camera 5. Homoge‐ neous liquid and air mixture is sprayed through the nozzle tip 6. While flowing, air suppressed in the nozzle earlier becomes very wide; it increases movement speed of drops (bubbles) and possibilities to get into foliage. Larger and heavier bubbles are less sensitive to blowing downwind, so they reach the sprayed surface quickly and cover it well while blowing upward. Productivity of the nozzle depends only on the dosage plates. In this case, the tip is not important. Cleft, hole or deflector tips may be used in a complex injector nozzle. After mixing with air, the volume of liquid increases; so the area of the diameter of the hole of the nozzle tip may be bigger than the area of the injector hole (at least twice as large).

1 – quick connection nut; 2 – adaptor; 3 – dosage plate; 4 – mixing camera; 5 – liquid pulsing damp camera; 6 – tip; 7 – rubber seal; 8 – injector [13].

**Figure 7.** Complex injector pneumohydraulic nozzle TurboDrop®

Additional advantages of complex pneumohydraulic nozzles:

**•** *Two-part (injector and tip) module construction*, theoretically allowing any flow form and drop size to be reached. The bigger the hole of a tip is, the larger the liquid drops sprayed. The patented dosage plate ensures secure operation of a nozzle when the tip hole is much bigger than the injector hole;


Compact injector pneumohydraulic nozzles (Figure 8) operate by a principle of the spout pump. In the inlet hole of the nozzle, the pressure reaches 8 bar; the solution gets into the injector with high speed and pumps air through holes on the sides. Differently from other nozzles, solution is sprayed not in drops but bubbles, because the air pumped into the nozzle frame mixes with the solution. Through the nozzle tip, the solution is sprayed with the pressure of only about 2 bar by larger and heavier bubbles; the danger of blowing drops downwind reduces, and it is possible to operate if the wind speed reaches up to 7 m s-1. Not infringing the wax layer, bubbles adhere to a leaf surface and only when the surface strain is too great do they explode. The surface sprayed in such a manner is covered better. Injector nozzles are almost universal: they are suitable for herbicides, fungicides, insecticides and acaricides, as well as for spraying growth activators and liquid mineral fertilizers. Using injector nozzles, the usage time of a sprayer increases, since it is possible to operate with a higher wind speed, to spray preparation mixes or preparations and liquid mineral fertilizers. Apart from that, less investment is needed if compared to pneumohydraulic nozzles, fewer drops are blown downwind, less depreciation occurs, and it may operate with a pressure of 2–20 bar (optimal operational pressure – 5–8 bar). In compact high-pressure injector nozzles, air is pumped through holes on the sides of the frame (Figure 8 a), and with low pressure ones from the bottom (Figure 8 b).

Advantages of compact low-pressure injector cleft flat-flow nozzles:


*A complex injector pneumohydraulic nozzle called TurboDrop®* (Figure 7) is made of an adaptor, quick connection nut, dosage plate, injector, mixing and pulsing damp camera, rubber tight and tip. Using the adaptor, it is possible to connect these two nozzles to any quick connection nuts 1. Round flow is sprayed to injector 8 through dosage plate 3. Air is pumped through holes present on injector sides. Air and liquid are mixed in camera 4. Liquid swirl is reduced in the widest zone of the mixing camera, and pulsing is damped in ring camera 5. Homoge‐ neous liquid and air mixture is sprayed through the nozzle tip 6. While flowing, air suppressed in the nozzle earlier becomes very wide; it increases movement speed of drops (bubbles) and possibilities to get into foliage. Larger and heavier bubbles are less sensitive to blowing downwind, so they reach the sprayed surface quickly and cover it well while blowing upward. Productivity of the nozzle depends only on the dosage plates. In this case, the tip is not important. Cleft, hole or deflector tips may be used in a complex injector nozzle. After mixing with air, the volume of liquid increases; so the area of the diameter of the hole of the nozzle

1

2

5 4

3

tip may be bigger than the area of the injector hole (at least twice as large).

8

7

6

Additional advantages of complex pneumohydraulic nozzles:

**Figure 7.** Complex injector pneumohydraulic nozzle TurboDrop®

rubber seal; 8 – injector [13].

38 Weed Biology and Control

than the injector hole;

1 – quick connection nut; 2 – adaptor; 3 – dosage plate; 4 – mixing camera; 5 – liquid pulsing damp camera; 6 – tip; 7 –

**•** *Two-part (injector and tip) module construction*, theoretically allowing any flow form and drop size to be reached. The bigger the hole of a tip is, the larger the liquid drops sprayed. The patented dosage plate ensures secure operation of a nozzle when the tip hole is much bigger

**Figure 8.** Nozzles of compact injector cleft flat-flow tips: a – high pressure; b – low pressure [9].

*With injector pneumohydraulic asymmetric flow nozzles,* liquid is sprayed at an 80º angle, i.e., 20º from the symmetric axis to one side and 60º to the other side. They are made of plastic in sizes 02 to 06. The recommended operational pressure for herbicide spraying is from 3 to 8 bar. Injector asymmetric flow nozzles may be used:


Injector pneumohydraulic asymmetric flow nozzles IS 80 produced by the company Lechler are acknowledged by the German Federal Biology Service (BBA) as a spraying means that reduces 90 % of losses.

*Two-flow injector compact pneumohydraulic nozzles* (e.g., Lechler IDKT) obtain a spraying angle of 120°, and liquid flow is sprayed 30° forward and back (Figure 9). Nozzle inlet and dosage

a – general view; b – section: 1 – withdrawal injector, 2 – frame; c – distribution scheme of liquid flows [9].

**Figure 9.** Two-flow injector compact pneumohydraulic nozzle

plate are made of chemicals and wear-proof ceramics. The range of the sprayed drops is from large to average. If spraying with the pressure up to 3 bars, few drops are blown downwind.

Nozzles are very compact (length 22 mm), and they satisfy the requirements of the German Federal Biology Service (BBA).

They are especially suitable for:


*With injector pneumohydraulic asymmetric flow nozzles,* liquid is sprayed at an 80º angle, i.e., 20º from the symmetric axis to one side and 60º to the other side. They are made of plastic in sizes 02 to 06. The recommended operational pressure for herbicide spraying is from 3 to 8 bar.

**Figure 8.** Nozzles of compact injector cleft flat-flow tips: a – high pressure; b – low pressure [9].

*b*

Liquid

Air Air

Injector Frame

Injector

Frame

Liquid

*a*

Air Air

**•** For spraying lines and plant rows and continuous spraying with ID nozzles equipped on

**•** For spraying continuously along protective bands of open water ponds or field borders;

Injector pneumohydraulic asymmetric flow nozzles IS 80 produced by the company Lechler are acknowledged by the German Federal Biology Service (BBA) as a spraying means that

*Two-flow injector compact pneumohydraulic nozzles* (e.g., Lechler IDKT) obtain a spraying angle of 120°, and liquid flow is sprayed 30° forward and back (Figure 9). Nozzle inlet and dosage

Injector asymmetric flow nozzles may be used:

**•** For protection of sensitive, closely growing plants;

**•** For spraying herbicides under the leaves of accumulative plants;

**•** For limitation of flat-flow in ventilator sprayers (the first and last nozzles).

**•** For spraying herbicides in gardens, vineries and arboretums;

the beam ends;

40 Weed Biology and Control

reduces 90 % of losses.

**•** Spraying herbicides in beetroot crops and in gardening.

Advantages of the two-flow injector compact pneumohydraulic nozzles Lechler IDKT:


*Asymmetric two-flow complex injector pneumohydraulic nozzles* by Agrotop called TurboDrop® HiSpeed are meant for operation with higher speed (> 8 km h-1). The liquid flow is sprayed 10° forward and 50° back. They feature compact construction, optimal coverage of the sprayed surfaces, and few drops drifting downwind. They are very suitable for spraying fungicides, insecticides and herbicides (after sprouting of cultivated plants). Vertical (e.g., stems, ears) and slantwise located (e.g., leaves) surfaces are covered better. Optimal operational pressure is 4– 8 bar. The nozzle inlet is made of wear-proof ceramics. It is easy to clean because the system of quick connection nuts is used. Plant protection products sprayed with the TurboDrop® HiSpeed nozzles cover plants optimally because, due to driving speed (> 8 km h-1), the attack angle in respect to a plant of both flows changes, i.e., back-directed flow reduces, and forward spraying flow increases.

*Rotation nozzles* distribute liquid with centrifugal force. According to operational position, *poppet rotation nozzles* may be divided into those spraying *horizontally*, *vertically* and *slantwise.* Usually, poppet rotation nozzles spray horizontally or slantwise. Only Girojet poppet rotation nozzles produced by Tecnoma spray vertically. Apart from that, plate diameter and rotation frequency of rotation nozzles produced by different producers vary. Usually, poppet rotation nozzles are turned by electric engines. Rotation poppet nozzles disperse liquid in small drops, the size range of which is very narrow. The size of the sprayed liquid drops depends on the plate rotation frequency, nozzle efficiency, viscosity of the sprayed liquid and surface tension. It is possible to change rotation frequency in nozzles through a wide range, from 800 to 8000 min-1. Depending on the construction, plate rotation frequency may be regulated by the electric stream rheostat (from Tecnoma and Spraying Systems) if changing pulleys of the tough transmission (from Micron and Krobath) or by regulation valves if changing the quantity of oil supplied to hydraulic engines (UTS Corp.). Productivity of poppet rotation nozzles is regulated by dosage plates. Depending on the pressure before the dosage plate (from 1.0 to 3.5 bar), productivity of these nozzles may range from 0.1 to 3.5 l min-1. The distance between poppet rotation nozzles mounted on the beam may be from 0.75 to 1.5 m. Optimal spraying height for Air Cone nozzles is 0.45 m, for RotoJet, 0.75 m, and for Girojet, 0.8 m. If the spraying aggregate drives at the speed of 6 km h-1, from 10 to 50 l of liquid are sprayed to one hectare [2].

The *rotation drum nozzle* is made of cylindrical metal mesh which turns around the hollow axle. The air transition screw turns the mesh. Solution is supplied to a hollow axle, and through a sphere closing valve it is supplied on a turning mesh. The turning mesh disperses solution by small drops, the size of which depends on the size of mesh holes and turning frequency. Frequency of mesh turning depends on the diameter of air transition screw, the form of blade, nozzle set angle and mounting place, flying speed, solution spraying norm and the type of flying apparatus.

The *preparation pouring system* integrated in nozzles is made of a preparation reservoir with washing and mixing nozzles, control taps and injector with control tap; in some cases (e.g., in hydraulic field sprayers produced by the company Amazone), there is a separate reservoir for mixing of flour-form plant protection products. It distributes plant protection products quickly and evenly in a sprayer reservoir and ensures secure work. The calibrated preparation reservoir is mounted in a comfortable place; thus, no additional measuring vessel is needed. It is convenient to wash the preparation vessel by a rotating the washing nozzle mounted in a reservoir. Flour-form preparations or larger quantities of carbamate are dissolved after turning on the effective mixing nozzles. Holding it by a handle, it is possible to lift and fix the prepa‐ ration reservoir in a transportation position, and when preparing a sprayed solution, it is possible to lower it down.

The *tow-bar* of a suspended hydraulic field sprayer may be mounted higher or lower to the tractor power supply axle or to the lower pullers of a rear hydraulic lift. It may have one or two coupling points, and may be stiff or with a changing turning angle. If a tow-bar with a handle is mounted to a rear hook of a tractor hydraulic lift, the air gap of a sprayer is bigger; moreover, it may be safer when working on slopes. If a tow-bar is mounted to the lower rods of a rear tractor hydraulic lift, the wheels of the sprayer follow the tractor tracks; however, in this case, the rods are overloaded.

Modern suspended field sprayers with tractor-track tracing devices beat crop less; they are more manoeuvrable, and they need less power for pulling as their resistance is smaller. It is important that tractor-track tracing devices work well in a hilly area.

Usually, the chassis of a suspended field sprayer has a stiff or amortizing suspension (e.g., spring or pneumatic). Pneumatic suspension of suspended field sprayers is simple, secure and tough; also, it does not require maintenance. The chassis of suspended field sprayers may be without brakes or with pneumatic or hydraulic brakes.

#### *2.2.3. Peculiarities of self-propelled hydraulic field sprayer construction*

**•** If compared to "normal", i.e., one-flow injector nozzle, there are more drops in the flows of

*Asymmetric two-flow complex injector pneumohydraulic nozzles* by Agrotop called TurboDrop® HiSpeed are meant for operation with higher speed (> 8 km h-1). The liquid flow is sprayed 10° forward and 50° back. They feature compact construction, optimal coverage of the sprayed surfaces, and few drops drifting downwind. They are very suitable for spraying fungicides, insecticides and herbicides (after sprouting of cultivated plants). Vertical (e.g., stems, ears) and slantwise located (e.g., leaves) surfaces are covered better. Optimal operational pressure is 4– 8 bar. The nozzle inlet is made of wear-proof ceramics. It is easy to clean because the system of quick connection nuts is used. Plant protection products sprayed with the TurboDrop® HiSpeed nozzles cover plants optimally because, due to driving speed (> 8 km h-1), the attack angle in respect to a plant of both flows changes, i.e., back-directed flow reduces, and forward

*Rotation nozzles* distribute liquid with centrifugal force. According to operational position, *poppet rotation nozzles* may be divided into those spraying *horizontally*, *vertically* and *slantwise.* Usually, poppet rotation nozzles spray horizontally or slantwise. Only Girojet poppet rotation nozzles produced by Tecnoma spray vertically. Apart from that, plate diameter and rotation frequency of rotation nozzles produced by different producers vary. Usually, poppet rotation nozzles are turned by electric engines. Rotation poppet nozzles disperse liquid in small drops, the size range of which is very narrow. The size of the sprayed liquid drops depends on the plate rotation frequency, nozzle efficiency, viscosity of the sprayed liquid and surface tension. It is possible to change rotation frequency in nozzles through a wide range, from 800 to 8000 min-1. Depending on the construction, plate rotation frequency may be regulated by the electric stream rheostat (from Tecnoma and Spraying Systems) if changing pulleys of the tough transmission (from Micron and Krobath) or by regulation valves if changing the quantity of oil supplied to hydraulic engines (UTS Corp.). Productivity of poppet rotation nozzles is regulated by dosage plates. Depending on the pressure before the dosage plate (from 1.0 to 3.5 bar), productivity of these nozzles may range from 0.1 to 3.5 l min-1. The distance between poppet rotation nozzles mounted on the beam may be from 0.75 to 1.5 m. Optimal spraying height for Air Cone nozzles is 0.45 m, for RotoJet, 0.75 m, and for Girojet, 0.8 m. If the spraying aggregate drives at the speed of 6 km h-1, from 10 to 50 l of liquid are sprayed to one hectare [2]. The *rotation drum nozzle* is made of cylindrical metal mesh which turns around the hollow axle. The air transition screw turns the mesh. Solution is supplied to a hollow axle, and through a sphere closing valve it is supplied on a turning mesh. The turning mesh disperses solution by small drops, the size of which depends on the size of mesh holes and turning frequency. Frequency of mesh turning depends on the diameter of air transition screw, the form of blade, nozzle set angle and mounting place, flying speed, solution spraying norm and the type of

the sprayed liquid; so, better coverage of the sprayed surfaces is reached;

**•** Prolonged lateral walls optimally secure nozzle inlet from damage; **•** Little probability of blockage since air pump holes are on the tip sides.

**•** Leaves and vertical surfaces (stems, ears);

spraying flow increases.

42 Weed Biology and Control

flying apparatus.

*A sprayer is called self-propelled* if it obtains a chassis and engine (Figure 10 a).

These nozzles differ from the put-on nozzles because their separate knots are not removed. Arguments for the self-propelled pesticide spraying machinery are:


Content of self-propelled nozzles' reservoir is usually from 2000 to 4000 l, and in some cases even 6000 l. Engine power reaches from 100 to 200 AG.

All wheels of a self-propelled sprayer are motive. Their gear is hydrostatic. High wheels ensure about 0.8 m clearance, and in some cases it may even reach 2.0 m (e.g., in sprayers of the company Dammann). In some models of self-propelled sprayers, it is possible to control them separately. Usually, operational width of self-propelled sprayers is from 24 to 36 m, and they may reach 51 m.

Depending on operational width, in self-propelled sprayers there may be one or two pumps the productivity of which is 200–300 l min-1. They obtain productive filling devices.

In self-propelled sprayers, the cabin of the operator is usually in front, and the beam with nozzles on the back. Only in France are self-propelled sprayers with the beam in front popular. It is thought that it is easier to control the beam when equipped in front of the sprayer.

*a* – general view: 1 – beam with nozzles, 2 – beam lifting and swing damp devices, 3 – clean water reservoir, 4 – main reservoir, 5 – cabin, 6 – frame, 7 – chassis

*b*

3 4 3

**Figure 10.** Self-propelled hydraulic field sprayer

*b* – chassis: 1 – airy amortizes, 2 – pendulous fork, 3 – hydraulic engines, 4 – pendulous frame [1].

Work with a self-propelled sprayer is safe and comfortable. Such sprayers are expensive, so the minimal annual volume of spraying works should be about 2000 ha. If 4000 ha are sprayed annually, only then do the maintenance costs of self-propelled and suspended sprayers become equal [2].

When choosing a self-propelled sprayer, their technical indices, economy and usage possibil‐ ities are most important.

#### *2.2.4. Peculiarities of the frame of pneumohydraulic field sprayers*

All wheels of a self-propelled sprayer are motive. Their gear is hydrostatic. High wheels ensure about 0.8 m clearance, and in some cases it may even reach 2.0 m (e.g., in sprayers of the company Dammann). In some models of self-propelled sprayers, it is possible to control them separately. Usually, operational width of self-propelled sprayers is from 24 to 36 m, and they

Depending on operational width, in self-propelled sprayers there may be one or two pumps

In self-propelled sprayers, the cabin of the operator is usually in front, and the beam with nozzles on the back. Only in France are self-propelled sprayers with the beam in front popular. It is thought that it is easier to control the beam when equipped in front of the sprayer.

3 4 3

*b*

*a* – general view: 1 – beam with nozzles, 2 – beam lifting and swing damp devices, 3 – clean water reservoir, 4 – main

*b* – chassis: 1 – airy amortizes, 2 – pendulous fork, 3 – hydraulic engines, 4 – pendulous frame [1].

7

6

1 2 1

*a*

1

the productivity of which is 200–300 l min-1. They obtain productive filling devices.

3 4 5

may reach 51 m.

44 Weed Biology and Control

2

reservoir, 5 – cabin, 6 – frame, 7 – chassis

**Figure 10.** Self-propelled hydraulic field sprayer

The pneumohydraulic field sprayer is a sprayer which contains a ventilator or compressor that blows air to pneumohydraulic nozzles attached to a beam or to air distribution channels that are mounted above the sprayer beam. Air flow divides the solution sprayed through the nozzles into small drops and carries them to the sprayed surfaces. Having reached the sprayed crops, air flow stops and starts to swirl. Small drops of the sprayed liquid also settle down on rarely reached surfaces, e.g., the lower part of a leaf and stems. These sprayers are produced by a number of companies. It is possible to separate two conceptions of pneumohydraulic field sprayers. The companies Knight, Danfoil and John Deere produce sprayers with pneumohy‐ draulic nozzles (Airtec, Twin-Fluid, Danfoil), in which solution is mixed with air. In pneumo‐ hydraulic field sprayers produced by the companies Rau, Dammann, Hardi and Kyndestoft, additional air flow is used; this air flow helps the sprayed liquid drops to reach the sprayed surface.

The construction of pneumohydraulic field sprayers produced by the companies Knight and John Deere is similar. Air is supplied to pneumohydraulic nozzles by a compressor (Figure 11). The sprayer by John Deere has a special device, the Twin-Fluid Controller, which may automatically regulate the size of the sprayed drops by changing the air pressure depending on wind speed and liquid pressure.

In a pneumohydraulic sprayer by Danfoil, air is blown at a high speed (which may be changed depending on working conditions) from the top to the bottom through a special pneumohy‐ draulic nozzle (Eurofoil) that disperses the solution supplied from the side onto crop. Move‐ ment speed of drops is high, so few drops drift downwind, and plants are sprayed more precisely. Solution drops settle down on the rear part of a leaf since air flow swirls intensively. When spraying with these sprayers, it is possible to reduce water quantity to 30 l ha-1.

In pneumohydraulic field sprayers, air flow is created by one or two axial ventilators; usually, they are driven hydraulically. It is distributed by flexible fabric hoses or channels of light metal. Various producers offer air distribution hoses of various forms and holes for their flow, e.g., in the pneumohydraulic field sprayers Rau, Douven (Kyndestoft) and Degania, air flows through 38 mm holes, though the distance between them may vary from 80 to 125 mm. In the first pneumohydraulic field sprayers of the company Hardi, air was blown through the entire length of the distribution hose. In the first pneumohydraulic field sprayers of the company Dammann, air was distributed through 1500 mm diameter aluminium pipes. From a pipe, air flew through holes, the measurements of which were 3 x 150 mm.

The construction of pneumohydraulic field sprayers produced by the companies Knight and John Deere is similar. Air is supplied to pneumohydraulic nozzles by a compressor (Figure 11). The sprayer by John Deere has a special device, the

Figure 11. The scheme of a pneumohydraulic field sprayer: 1 – air filter; 2 – pump; 3 – compressor; 4 – air line control panel; 5 – cleaning brush; 6 – control taps of air line sections; 7 – control panel of pressure line; 8 – control taps of pressure sections; 9 – pneumohydraulic nozzles; 10 – section filters of 1 – air filter; 2 – pump; 3 – compressor; 4 – air line control panel; 5 – cleaning brush; 6 – control taps of air line sections; 7 – control panel of pressure line; 8 – control taps of pressure sections; 9 – pneumohydraulic nozzles; 10 – section filters of pressure line; 11 – clean water tank; 12 – reservoir; 13 – mixer; 14 – preparation tank [14].

In a pneumohydraulic sprayer by Danfoil, air is blown at a high speed (which may be changed depending on working

pressure line; 11 – clean water tank; 12 – reservoir; 13 – mixer; 14 – preparation tank [14]. **Figure 11.** The scheme of a pneumohydraulic field sprayer

In the newest pneumohydraulic field sprayers of the company Dammann, various cleft flatflow nozzles are used, and the sprayed drops are secured from wind effect by two air flows (in front of the spraying beam and behind it, Figure 12). Air is distributed through light metal pipes. This system creates an injector effect, i.e., it pumps drops to crop. Advantages: better effect of pesticides, lower expenditure, fewer drops blown downwind of the sprayed crops. conditions) from the top to the bottom through a special pneumohydraulic nozzle (Eurofoil) that disperses the solution supplied from the side onto crop. Movement speed of drops is high, so few drops drift downwind, and plants are sprayed more precisely. Solution drops settle down on the rear part of a leaf since air flow swirls intensively. When spraying with these sprayers, it is possible to reduce water quantity to 30 l ha-1. In pneumohydraulic field sprayers, air flow is created by one or two axial ventilators; usually, they are driven hydraulically. It is distributed by flexible fabric hoses or channels of light metal. Various producers offer air distribution

hoses of various forms and holes for their flow, e.g., in the pneumohydraulic field sprayers Rau, Douven (Kyndestoft) and Degania, air flows through 38 mm holes, though the distance between them may vary from 80 to 125 mm. In the first pneumohydraulic field sprayers of the company Hardi, air was blown through the entire length of the distribution hose. In the first pneumohydraulic field sprayers of the company Dammann, air was distributed through 1500 mm diameter

a – view of sprayer beams with integrated ventilator: 1 – air channel, 2 – ventilator, 3 – sprayer reservoir, 4 – beam lifting device;

b – view of sprayed liquid drops: 1 – flow of drops, 2 – nozzles, 3 – beam with air distribution channel; c – scheme of location of nozzles and air flow holes: 1 – holes for air flow, 2 – distribution pipe, 3 – nozzles [15].

**Figure 12.** Pneumohydraulic field sprayer of the company Dammann

In the newest pneumohydraulic field sprayers of the company Dammann, various cleft flatflow nozzles are used, and the sprayed drops are secured from wind effect by two air flows (in front of the spraying beam and behind it, Figure 12). Air is distributed through light metal pipes. This system creates an injector effect, i.e., it pumps drops to crop. Advantages: better effect of pesticides, lower expenditure, fewer drops blown downwind of the sprayed crops.

In pneumohydraulic field sprayers, air flow is created by one or two axial ventilators; usually, they are driven hydraulically. It is distributed by flexible fabric hoses or channels of light metal. Various producers offer air distribution hoses of various forms and holes for their flow, e.g., in the pneumohydraulic field sprayers Rau, Douven (Kyndestoft) and Degania, air flows through 38 mm holes, though the distance between them may vary from 80 to 125 mm. In the first pneumohydraulic field sprayers of the company Hardi, air was blown through the entire length of the distribution hose. In the first pneumohydraulic field sprayers of the company Dammann, air was distributed through 1500 mm diameter

In a pneumohydraulic sprayer by Danfoil, air is blown at a high speed (which may be changed depending on working conditions) from the top to the bottom through a special pneumohydraulic nozzle (Eurofoil) that disperses the solution supplied from the side onto crop. Movement speed of drops is high, so few drops drift downwind, and plants are sprayed more precisely. Solution drops settle down on the rear part of a leaf since air flow swirls intensively. When

1 – air filter; 2 – pump; 3 – compressor; 4 – air line control panel; 5 – cleaning brush; 6 – control taps of air line sections; 7 – control panel of pressure line; 8 – control taps of pressure sections; 9 – pneumohydraulic nozzles; 10 – section filters of

1 – air filter; 2 – pump; 3 – compressor; 4 – air line control panel; 5 – cleaning brush; 6 – control taps of air line sections; 7 – control panel of pressure line; 8 – control taps of pressure sections; 9 – pneumohydraulic nozzles; 10 – section filters

liquid return line

air line

The construction of pneumohydraulic field sprayers produced by the companies Knight and John Deere is similar. Air is supplied to pneumohydraulic nozzles by a compressor (Figure 11). The sprayer by John Deere has a special device, the Twin-Fluid Controller, which may automatically regulate the size of the sprayed drops by changing the air pressure

10 9

12

13 14

depending on wind speed and liquid pressure.

46 Weed Biology and Control

Figure 11. The scheme of a pneumohydraulic field sprayer:

liquid suction line liquid pressure line

**Figure 11.** The scheme of a pneumohydraulic field sprayer

1

4

5

pressure line; 11 – clean water tank; 12 – reservoir; 13 – mixer; 14 – preparation tank [14].

of pressure line; 11 – clean water tank; 12 – reservoir; 13 – mixer; 14 – preparation tank [14].

<sup>2</sup> <sup>3</sup>

6 8

7

11

spraying with these sprayers, it is possible to reduce water quantity to 30 l ha-1.

In the opinion of some producers (e.g., Kyndestoft and Douven), it would be enough to direct the trail of small drops to the crop. The smaller air quantity is needed for settling down liquid drops on the sprayed surfaces.

In Airsprayer sprayers of the company Kyndestoft, a ventilator supplies air by a round fabric channel that is mounted above the spraying beam. This air flow (the vertical angle of which may be modified from 0 to 40°) protects sprayed solution drops from downwind blow. If a vacuum is formed, the trail of drops is prolonged (to 1.20 m), and plants are covered more evenly and better (small drops); fewer drops are settled down on the ground. Preparations work better and more reliably; apart from this, productivity doubles since it is possible to reduce by up to 50 % expenditures on preparations and water. Usually, productivity of the ventilator in pneumohydraulic sprayers is regulated.

According to conception of the companies Degania and Rau, the fact that air flow directs all drops of the sprayed liquid to the crop is an advantage. In Rau AirPlus sprayers, additional air flow is supplied vertically downwards, and the solution is sprayed by small drops (as narrow a drop range as possible) using cleft cone-flow nozzles; spraying direction versus the vertical of these nozzles may be changed. Using sprayers of this company, it is possible to reduce expenditures on preparations by 25–30 %; 100 l ha-1 of water is enough. Apart from this, it is possible to almost double working speed and to spray if wind speed is up to 8 m s-1.

In pneumohydraulic field sprayers of the company Hardi, only cleft flat-flow nozzles are used; the angle between liquid and air flows remains constant, but it may be changed in respect to the vertical ± 30°. In this case, 100 l ha-1 of water is enough, and it is possible to use 25–30 % less pesticides and spray with wind speed up to 9 m s-1.

If spraying with pneumohydraulic field sprayers (e.g., Hardi Twin, Dammann DAS or Kyndestoft AirSprayer), a larger amount of air opens crops widely; however, too strong air flow may reduce the spraying angle of the cleft flat-flow nozzles, and, due to this, slantwise distribution of the sprayed liquid worsens. When crops are opened widely, drops of average size may also reach the lower part of a plant. In any case, spraying with pneumohydraulic sprayers, there should be as few large drops as possible because swirling air flow does not affect their flying trajectory. Additional air flow increases movement speed of these drops, so the possibility that they would spring back or roll down the sprayed surfaces increases significantly [16].

In pneumohydraulic field sprayers using cleft flat-flow nozzles, productivity may vary from 0.3 to 1.2 l min-1 (if operational pressure is 3 bar). Spraying height varies from 0.4 to 0.6 m. For one hectare, from 50 to 400 l of liquid may be sprayed [16, 17].

Usually, cone-flow nozzles for small drops are mounted on the sprayer beam at the distance of 0.25 m. Their optimal spraying height is 0.6–0.7 m, and operational pressure about 4.0 bar. It is not recommended to spray with cone-flow nozzles with the pressure less than 3 bar since spraying angle reduces and slantwise distribution of the sprayed liquid worsens. From 50 to 600 l may be sprayed for one hectare [18].

Many authors recommend a norm sprayed by pneumohydraulic field sprayers between 100 and 200 l ha-1 [10, 19]. The amount of air is determined depending on wind strength, type of sprayed cultivated plants, their height and density.

When spraying crops in their early growth periods, by pneumohydraulic field sprayers, amount of air should be minimal or the ventilator should be turned off. When plants are small, and the drops in the crop are not stopped, additional air flow increases drift of small liquid drops [20].

On the whole, farmers in Western Europe have a positive opinion of this complex and rather expensive machinery; however, the promised effect is not always achieved. For instance, using pneumohydraulic field sprayers, it is not always possible to reduce 30 % of expenditures on plant protection products. It depends on protection preparations and sprayed plants. The sprayed surfaces are covered very well; so, it is possible to reduce expenditures on contact preparations. However, it is not advisable to reduce norms of systemic plant protection products. Good results are obtained by spraying the reduced norms of herbicides when eliminating weeds in potato and sugar beet crops; however, it is not advisable to reduce norms of soil herbicides. Depending on the sprayed plants, insecticide effectiveness problems may appear because a higher water amount to each hectare is needed.

Using pneumohydraulic field sprayers, it is very important to appropriately set air pressure. If it is too high, solution may be sprayed by small drops that may be blown downwind or evaporate. If air pressure is too low, due to large drops, preparation activity may worsen. Using this spraying technique, solution concentration is very high; so it is important that its remains are small. Let us remember that 50 l of solution is enough to spray 0.5–1.0 ha. The diameter of the sprayer hoses should not exceed 10 mm, so that sediments are not formed.

Specialists advise checking new sprayers with pneumohydraulic nozzles in special work‐ shops, since it is rather difficult to determine the optimal liquid slantwise distribution. Nozzles of this type should be washed very well because even insignificant sediments on a deflector may considerably affect the evenness of liquid slantwise distribution.

#### **2.3. Automatic weed recognition systems**

distribution of the sprayed liquid worsens. When crops are opened widely, drops of average size may also reach the lower part of a plant. In any case, spraying with pneumohydraulic sprayers, there should be as few large drops as possible because swirling air flow does not affect their flying trajectory. Additional air flow increases movement speed of these drops, so the possibility that they would spring back or roll down the sprayed surfaces increases

In pneumohydraulic field sprayers using cleft flat-flow nozzles, productivity may vary from 0.3 to 1.2 l min-1 (if operational pressure is 3 bar). Spraying height varies from 0.4 to 0.6 m. For

Usually, cone-flow nozzles for small drops are mounted on the sprayer beam at the distance of 0.25 m. Their optimal spraying height is 0.6–0.7 m, and operational pressure about 4.0 bar. It is not recommended to spray with cone-flow nozzles with the pressure less than 3 bar since spraying angle reduces and slantwise distribution of the sprayed liquid worsens. From 50 to

Many authors recommend a norm sprayed by pneumohydraulic field sprayers between 100 and 200 l ha-1 [10, 19]. The amount of air is determined depending on wind strength, type of

When spraying crops in their early growth periods, by pneumohydraulic field sprayers, amount of air should be minimal or the ventilator should be turned off. When plants are small, and the drops in the crop are not stopped, additional air flow increases drift of small liquid

On the whole, farmers in Western Europe have a positive opinion of this complex and rather expensive machinery; however, the promised effect is not always achieved. For instance, using pneumohydraulic field sprayers, it is not always possible to reduce 30 % of expenditures on plant protection products. It depends on protection preparations and sprayed plants. The sprayed surfaces are covered very well; so, it is possible to reduce expenditures on contact preparations. However, it is not advisable to reduce norms of systemic plant protection products. Good results are obtained by spraying the reduced norms of herbicides when eliminating weeds in potato and sugar beet crops; however, it is not advisable to reduce norms of soil herbicides. Depending on the sprayed plants, insecticide effectiveness problems may

Using pneumohydraulic field sprayers, it is very important to appropriately set air pressure. If it is too high, solution may be sprayed by small drops that may be blown downwind or evaporate. If air pressure is too low, due to large drops, preparation activity may worsen. Using this spraying technique, solution concentration is very high; so it is important that its remains are small. Let us remember that 50 l of solution is enough to spray 0.5–1.0 ha. The diameter of

Specialists advise checking new sprayers with pneumohydraulic nozzles in special work‐ shops, since it is rather difficult to determine the optimal liquid slantwise distribution. Nozzles of this type should be washed very well because even insignificant sediments on a deflector

the sprayer hoses should not exceed 10 mm, so that sediments are not formed.

may considerably affect the evenness of liquid slantwise distribution.

one hectare, from 50 to 400 l of liquid may be sprayed [16, 17].

600 l may be sprayed for one hectare [18].

sprayed cultivated plants, their height and density.

appear because a higher water amount to each hectare is needed.

significantly [16].

48 Weed Biology and Control

drops [20].

In recent years, automatic recognition of weeds has been attempted in two ways. Some try to recognize weeds by optical-electronic sensors measuring their reflecting light spectrum, and others try to use digital video cameras and handling systems for the filmed views.

In the first approach, it is possible to separate only green plants from the soil surface. Using optical-electronic sensors, the daylight spectrum reflecting from green plants and the soil surface is measured; the obtained data are processed, and the nozzles are controlled accordingly. The weed recognition system Detectspay® (Figure 13) operates by this principle. This system is meant to spray herbicides in the mould humus or till sprouting of cultivated plants. According to Biller, if compared to general spraying, usage of the weed recognition system Detectspay® may reduce expenditures on plant protection products by an average of 52 %. As various research shows, under favourable conditions, it is possi‐ ble to reduce expenditures on plant protection products by 33–68 %, and under unfavour‐ able conditions by only 10–30 % [21, 22].

Wartemberg used optical-electronic sensors with DGPS equipment, and recognized weeds comparatively well and fixed their place in the field [23].

1 – sprayer beam; 2 – environment light sensor; 3 – spraying computer; 4 – wires; 5 – magnetic valve; 6 – spraying sensor [23].

**Figure 13.** Distribution scheme of optical-electronic sensors using weed recognition system Detectspay®

Kühbauch offered a totally different way to recognize weeds, i.e., by analysing images filmed by a video camera. Using GPS devices too, the location of the filmed views is determined very precisely (Figure 14). Analysing the filmed images by special programmes, types of weed and their distribution on the field are determined. The received data are transferred to digital weed maps (Figure 15). When using computers of the older generation, recognition of one sort weed took two seconds; thus, it was quite complicated to control the nozzles at the same time [2].

1 – video camera; 2 – computer; 3 – DGPS receiver; 4 – means of transportation [2].

**Figure 14.** Location scheme of equipment when filmed by the video camera used for weed recognition

weeds to be sprayed with herbicides

no weeds or their number does not exceed the limits of the damage

areas to be sprayed with herbicide

**Figure 15.** Maps of crop weeding (a) and spraying (b) [2].

With a speed of 25 frames per second, the computer determines the weed outline by analysing the saved images. According to the photos of weed outline and certain proportions, specific parameters are calculated, e.g., the ratio between the outline of each weed and photo. These specific parameters are used for weed recognition. The performed research shows that the accuracy of weed recognition using view analysis equipment may range from 60 to 90 %. Such precision is sufficient for making maps for crop weeding and spraying [2].

DGPS 3

2

1

50 Weed Biology and Control

1 – video camera; 2 – computer; 3 – DGPS receiver; 4 – means of transportation [2].

weeds to be sprayed with herbicides

areas to be sprayed with herbicide

**Figure 15.** Maps of crop weeding (a) and spraying (b) [2].

no weeds or their number does not exceed the limits of the damage

**Figure 14.** Location scheme of equipment when filmed by the video camera used for weed recognition

4

Since weed dispersion is related to a certain location, it is possible to use maps of crop weeding in subsequent years to make new maps of crop weeding and spraying. Using DGPS equipment, the place of spraying aggregate in the field is determined accurately, and the computer controls the spraying process according to a crop spraying map (Figure 16). Magnetic valves open the nozzles in exactly the place where the weeds were noticed while making a crop weeding map. It is thought that using this precise farming method, it is possible to save from 30 to 50 % of herbicides [2].

<sup>1 –</sup> sprayer's beam sections with nozzles; 2 – magnetic valves; 3 – valve for pressure regulation; 4 – pump; 5 – reser‐ voir; 6 – flow meter; 7 – pressure gauge; 8 – DGPS receiver; 9 – computer with installed maps of crop weeding and spraying; 10 – spraying computer with control switches of beam sections [2].

**Figure 16.** Sprayer control scheme according to a crop spraying map

At this point, for a wider usage of the means of precise farming, some technical details and high prices have become an obstacle; however, in the future, positive economic and environ‐ mental protection aspects should help to achieve a breakthrough in this field.

Special sensors for plant protection are offered (Figure 17). The inexpensive and solid ultra‐ sound sensor P3 may determine the state of a crop irrespective of time, i.e., it is possible to work even at night. This sensor may determine the height of crops, the number and position of plant leaves, and the amount of biomass. Using agronomic algorithms with the information supplied by a sensor, it is possible to evaluate the present situation and spray separate field places by different norms of plant protection products. According to the state, it is possible to choose the appropriate aggregate driving speed, working pressure and norm of liquid spraying. Since the equipment quickly reacts to changes in crop state, the ultrasound sensor may be fastened directly on the sprayer beam. So far, these sensors have been mostly used for spraying growth regulators; however, their usage in other areas is very likely.

**Figure 17.** Ultrasound sensor P3 is attached to a field sprayer's beam for precise plant protection [24].

OptRx sensors (Ag Leader® Technology, USA) are used to research optical peculiarities of the cultivated plants (Figure 18). These sensors measure the reflected rays in ranges of infrared and red spectra (Figure 19):

*R*760 – reflected 760 nm wavelength infrared rays,

Special sensors for plant protection are offered (Figure 17). The inexpensive and solid ultra‐ sound sensor P3 may determine the state of a crop irrespective of time, i.e., it is possible to work even at night. This sensor may determine the height of crops, the number and position of plant leaves, and the amount of biomass. Using agronomic algorithms with the information supplied by a sensor, it is possible to evaluate the present situation and spray separate field places by different norms of plant protection products. According to the state, it is possible to choose the appropriate aggregate driving speed, working pressure and norm of liquid spraying. Since the equipment quickly reacts to changes in crop state, the ultrasound sensor may be fastened directly on the sprayer beam. So far, these sensors have been mostly used for

spraying growth regulators; however, their usage in other areas is very likely.

52 Weed Biology and Control

**Figure 17.** Ultrasound sensor P3 is attached to a field sprayer's beam for precise plant protection [24].

*R*670 – reflected 670 nm wavelength red light rays.

**Figure 18.** General view of a sensor for plant optical analysis, OptRx [25].

**Figure 19.** Part of reflected rays depending on the length of a wave [25].

*NDVI* index is recommended for use until the 32nd wheat growth stage, and in the later stages *NDRE* is offered:

*R*760 – reflected 760 nm wave length infrared rays,

*R*730 – reflected 730 nm wave length red light rays.

## **3. Weed control by mechanical means**

#### **3.1. Cultivators**

#### *3.1.1. Purpose and requirements of cultivation agromachinery*

Cultivators of continuous operation moulder soil, insert mineral fertilizers into the soil, exterminate weeds and prepare soil for growth.

Row-spacing cultivators cut grass, locally insert mineral fertilizers into soil, moulder rowspacing and moulder up plants.

*Requirements of agromachinery for continuous cultivation***.** Soil is constantly cultivated by observing mould humus and mouldering soil before sowing. Unevenness of soil mouldering is allowed at no more than ± 1 cm. The surface of the cultivated soil should be of a small grain structure, and weeds should be totally destroyed. Soil surface waviness of no more than 3–4 cm is allowed; so often the soil is cultivated and harrowed.

*Requirements of agromachinery for row-spacing cultivation***.** Row-spacing is mouldered at the depth of 4–12 cm. The allowed deviation from the set mouldering depth is not more than ± 1 cm, and deviation from the insert norm of fertilizers is ± 10 %. For the first time, row-spacing is mouldered in the depth of 6-8 cm leaving protection zone for 10–12 cm; for the second time, row-spacing is mouldered in the depth of 8–10 cm leaving protection zone not less than 12 cm, and for the third time, it is mouldered not shallower than 10 cm leaving protection zone 12– 18 cm. Driving speed of row-spacing machinery is 5–6 km h-1. When loosening row-spacing, not less than 95 % of weed should be destroyed.

#### *3.1.2. Classification*

Cultivators are classified as continuous soil operation, hard and row-spacing. They may have passive or rotating operational parts. Operational parts may be rotated by force (rotor cultivators); operational parts may be rotated by force (rotor cultivators) or may rotate when operational parts are in contact with soil (rotation). Both types of cultivators may rotate around the vertical and horizontal axle. According to their connection with energetic source, cultiva‐ tors are classified into suspended and put-on.

#### *3.1.3. Construction and operational parts*

*Continuous operation cultivators with passive operational parts* (Figure 20). These cultiva‐ tors are made of a frame 4, to which operational parts are attached – ploughshares, support wheels 3, suspension or hanging device and harrow hanging device 7. Ploughshare is made of handle 6 and tip 5. A handle may be stiff, made stiff with a spring protector or spring. The ploughshare with spring handle is the most widespread, and it is called a spring ploughshare. Spring handles may be of S or C form. Handles of S form are suitable to work in stony soil since they are elastic and do not break when caught by an obstacle. When working with a cultivator with spring handles, the driving speed is 9–12 km h-1; when they vibrate, soil is not stuck around them, and the soil is well loosened.

*a* – general view; *b* – joint equipment of ploughshare; 1 – hanging device; 2 – support; 3 – support wheel; 4 – frame; 5 – tip; 6 – handle; 7 – harrow hanging device; 8 – hydraulic cylinder; 9 – pivot; 10 – plug; 11 – spring; 12 – carrier [26].

#### **Figure 20.** Continuous operation cultivator

**3. Weed control by mechanical means**

exterminate weeds and prepare soil for growth.

not less than 95 % of weed should be destroyed.

tors are classified into suspended and put-on.

*3.1.3. Construction and operational parts*

spacing and moulder up plants.

*3.1.1. Purpose and requirements of cultivation agromachinery*

cm is allowed; so often the soil is cultivated and harrowed.

Cultivators of continuous operation moulder soil, insert mineral fertilizers into the soil,

Row-spacing cultivators cut grass, locally insert mineral fertilizers into soil, moulder row-

*Requirements of agromachinery for continuous cultivation***.** Soil is constantly cultivated by observing mould humus and mouldering soil before sowing. Unevenness of soil mouldering is allowed at no more than ± 1 cm. The surface of the cultivated soil should be of a small grain structure, and weeds should be totally destroyed. Soil surface waviness of no more than 3–4

*Requirements of agromachinery for row-spacing cultivation***.** Row-spacing is mouldered at the depth of 4–12 cm. The allowed deviation from the set mouldering depth is not more than ± 1 cm, and deviation from the insert norm of fertilizers is ± 10 %. For the first time, row-spacing is mouldered in the depth of 6-8 cm leaving protection zone for 10–12 cm; for the second time, row-spacing is mouldered in the depth of 8–10 cm leaving protection zone not less than 12 cm, and for the third time, it is mouldered not shallower than 10 cm leaving protection zone 12– 18 cm. Driving speed of row-spacing machinery is 5–6 km h-1. When loosening row-spacing,

Cultivators are classified as continuous soil operation, hard and row-spacing. They may have passive or rotating operational parts. Operational parts may be rotated by force (rotor cultivators); operational parts may be rotated by force (rotor cultivators) or may rotate when operational parts are in contact with soil (rotation). Both types of cultivators may rotate around the vertical and horizontal axle. According to their connection with energetic source, cultiva‐

*Continuous operation cultivators with passive operational parts* (Figure 20). These cultiva‐ tors are made of a frame 4, to which operational parts are attached – ploughshares, support wheels 3, suspension or hanging device and harrow hanging device 7. Ploughshare is made of handle 6 and tip 5. A handle may be stiff, made stiff with a spring protector or spring. The ploughshare with spring handle is the most widespread, and it is called a spring ploughshare. Spring handles may be of S or C form. Handles of S form are suitable to work in stony soil since they are elastic and do not break when caught by an obstacle. When working with a

**3.1. Cultivators**

54 Weed Biology and Control

*3.1.2. Classification*

Tips of a ploughshare may be spear, forged or universal arrow 5. Spear and forged tips may be tippled and one-side. If one end of a tippled tip is worn out, it may be turned over to another end. Universal arrow tips are used for weed cutting and soil mouldering. The main parameters of the arrow tips are operational width, attack angle and blade angle. Attack angle is formed by a tip surface with a horizontal surface, and it influences mouldering intensity. The attack angle of a universal arrow tip is 28–30°. The blade angle that is made by the tip blade with the axial line has influence when cutting weeds. The angle is chosen in such a way that weed would be cut when sliding on the tip blade; it may be 30–32.5°, and the angle's operational width may be 145–330 mm.

The ploughshare is attached to a cultivator frame jointly (Figure 20 b) or stiffly. The jointly attached ploughshare copies the soil surface better and cultivates soil more evenly. When attaching ploughshares jointly, they are fastened to the frame by a carrier 12; also, pivots 9 with pressed springs 11 are inserted. If changing position of a plug 10 in the holes of a pivot 9, pressing force of the spring is regulated.

Continuous operation cultivators, ploughshares which have stiff handles, may have spring protectors. Meeting an obstacle, the spring deforms, and the ploughshare straightens. After the ploughshare passes the obstacle, it is returned to the initial position by the spring.

In order that the ploughshares are not stuffed with plant remains, they are located in two or three rows, at the distance of 400–500 mm. Ploughshares with arrow tips are usually located in two rows with an overlap of 40–60 mm, so that on turns no uncultivated soil zones remained. Spring ploughshares are usually located in three rows. Distance between furrows is 6–10 times larger than the width of the ploughshare itself. Ploughshares located in such a way loosen the soil constantly, since the soil is deformed more widely than the width of a ploughshare.

*Row-spacing cultivators with passive operational parts.* The row-spacing cultivator (Figure 21) is made up of: frame 1; hanging device 2; hydraulic cylinders 3, by which lateral sections are lifted during transportation; regulation device for loosening depth 4; protective disc 5; and section of ploughshares 6. The operational parts of such cultivators are ploughshares. Plough‐ shares are fastened in sections for operation in one row-spacing.

1 – frame; 2 – hanging device; 3 – hydraulic cylinders; 4 – regulation device for loosening depth; 5 – protective disc; 6 – section of ploughshares [27].

**Figure 21.** Row-spacing cultivator

Sections (Figure 22) are attached to the frame 10 by a parallelogram device so that their bending angle does not change when ploughshares are lifted or settled down. The parallelogram fastening device is made of two brackets 1 and 3, lower 9 and upper 2 rods. Bending angle of ploughshares is regulated by the upper rod. The section is made of a carrier 5, ploughshares 7 and support wheel 8. Loosening depth is regulated by a screw 4. The support wheel copies soil unevenness well, so ploughshares enter the soil at the determined depth.

1 and 3 – brackets; 2 – upper rod; 4 – screw; 5 – carrier; 6 – protective convex; 7 – ploughshares; 8 – support wheel; 9 – lower rod; 10 – frame [28].

Row-spacing cultivators have various sets of ploughshares and fertilizing machinery. Fertil‐ izing machinery may have plate or screw fertilizer feeders. Fertilizer feeders are turned by cultivator wheels through chain gears and reducers. In row-spacing cultivators, there are oneside knife *b*, arrow *a*, arrow universal, forged *e*, fertilizing *d*, accumulative *k* and turning ploughshares *g*, protective plates *c*, protective convexes *f* and weeding rotors *h* (Figure 23).

*One-side knife ploughshares* (Figure 23 b) cut weeds and loosen soil at the depth of 40–60 mm. They are made up of a horizontal knife and a vertical wall. Horizontal knife cuts weed, and vertical wall protects plants against soil heaping up. One-side ploughshares may be left or right side. Their operational width is 80–200 mm.

*Arrow ploughshares* (Figure 23 a) are in the form of an arrow. They are meant for weed cutting and soil loosening at the depth of 40–60 mm. Blades of these ploughshares make an angle of 60–70°. Blades of arrow universal ploughshares are lifted, so they do not only cut weed, but also loosen soil in the depth of up to 120 mm.

*Forged ploughshares* (Figure 23 e) are narrow (about 20 mm wide). They loosen row-spacing in the depth of 100–160 mm.

*Fertilizing ploughshares* (Figure 23 d) are used additionally for local fertilization of plants during vegetation. They are made of a forged ploughshare with a funnel attached to it.

*a* – arrow ploughshare; *b* – one-side knife; *c* – protective plates; *d* – fertilizing ploughshare; *e* – forged ploughshare; *f* – protective convex; *g* – turning ploughshare; *h* – weeding rotors; *k* – hilling-up ploughshare [26].

**Figure 23.** Operational parts of a row-spacing cultivator

are lifted during transportation; regulation device for loosening depth 4; protective disc 5; and section of ploughshares 6. The operational parts of such cultivators are ploughshares. Plough‐

1 – frame; 2 – hanging device; 3 – hydraulic cylinders; 4 – regulation device for loosening depth; 5 – protective disc; 6 –

Sections (Figure 22) are attached to the frame 10 by a parallelogram device so that their bending angle does not change when ploughshares are lifted or settled down. The parallelogram fastening device is made of two brackets 1 and 3, lower 9 and upper 2 rods. Bending angle of ploughshares is regulated by the upper rod. The section is made of a carrier 5, ploughshares 7 and support wheel 8. Loosening depth is regulated by a screw 4. The support wheel copies

1 and 3 – brackets; 2 – upper rod; 4 – screw; 5 – carrier; 6 – protective convex; 7 – ploughshares; 8 – support wheel; 9 –

Row-spacing cultivators have various sets of ploughshares and fertilizing machinery. Fertil‐ izing machinery may have plate or screw fertilizer feeders. Fertilizer feeders are turned by cultivator wheels through chain gears and reducers. In row-spacing cultivators, there are oneside knife *b*, arrow *a*, arrow universal, forged *e*, fertilizing *d*, accumulative *k* and turning ploughshares *g*, protective plates *c*, protective convexes *f* and weeding rotors *h* (Figure 23).

soil unevenness well, so ploughshares enter the soil at the determined depth.

shares are fastened in sections for operation in one row-spacing.

section of ploughshares [27].

56 Weed Biology and Control

lower rod; 10 – frame [28].

**Figure 22.** Section of row-spacing cultivator

**Figure 21.** Row-spacing cultivator

Potatoes and other hilled-up vegetables are hilled-up by row-spacing cultivators with *hillingup ploughshares*. These ploughshares are of various constructions. Turning hilling-up plough‐ shares (Figure 23 k) are made of a handle tip and two tipplers turning soil into both sides of a row. Tipplers may be continuous, rod and complex. When hilling up with ploughshares with rod tipplers, row sides and bottom are pressed less. Turning ploughshares with two plough‐ shares mounted to spring handles are used less often. Hilling-up ploughshares loosen soil up to the depth of 160 mm, and make the row height up to 250 mm.

*Plate hilling-up ploughshares* are made of two convex plates mounted in the angle of driving direction; they turn soil in to both sides. When hilling up, plates turn; so, their resistance to gravitation is smaller than that of turning hilling-up ploughshares. Usually, plate hilling-up ploughshares are mounted to potato planters in order to cover sowing potatoes with soil.

*Turning ploughshares* (Figure 23 g) are made of a handle and a tippler. They may be left- or right-sided, used for operation in row-spacing of potatoes or other hilling-up vegetables. These ploughshares are located at the distance of 250–270 mm on both sides of plants. They cut weed, loosen soil in the depth of 60 mm and cover weeds in the plant protection zone.

*Weeding rotors* (Figure 23 h) loosen soil and destroy weed in row-spacing. Working with weeding rotors, a narrower protective zone around plant rows is left. They are made of a bend rotor in respect to soil which turns around the axle fastened to the handle. On the sides of a rotor, axles are fastened to which the cultivator is mounted. During operation, cultivators turn around their axles and turn together with a rotor; so weeds are rooted out and covered with soil. If plants are lower than 50 mm, a shield is attached to the handle; the shield protects plants from covering with soil.

*Protective convexes* (Figure 23 f) are attached above plant rows and protect them from covering with soil. They are used if plants are lower than 50 mm. Protective plates are also used to protect plants from being covered with soil (Figure 23 c).

In modern row-spacing cultivators, *cut discs* 5 (Figure 3.5) are mounted on the sides of sections in order to protect plants from being covered with soil and to shake soil off plants. When rolling, cut discs move ploughshares up and down; in this case, soil is better shaken off the roots of weeds, and weeds are destroyed better.

*Rotor row-spacing cultivators.* Their operational parts are rotors turning around the hori‐ zontal axle in the driving direction; knives of various forms are attached to rotors. Rotors are turned by a tractor operational shaft through gears. Width of rotors is adapted for loosening of row-spacing, the width of which is not narrower than 450 mm. The soil is hilled up by the gear frame by a passive ploughshare.

Row-spacing of potatoes, sugar beet and strawberries is loosened by rotor cultivators. It is not possible to use them in light soil since the structure of the soil is destroyed (many small particles are created; in rainy weather these particles form a crust). When loosening stony soil by rotor row-spacing cultivators, knives break [26].

#### **3.2. Harrow**

#### *3.2.1. Purpose of harrow and requirements for agromachinery*

*Purpose of harrow.* The surface of the soil is levelled and loosened, bigger clods are chopped, and soil preparation for sowing is completed. In spring, soil surface is loosened by a harrow; an isolation layer that does not allow dampness to disappear is formed. The harrow destroys springing out weed and cuts the growing ones. The harrow may also be used to insert mineral fertilizers and seeds of perennial grass and other plants. The harrow may be used for harrowing the sprung out crop, aiming to destroy springing weed and chop-forming soil crust.

*Requirements for agromachinery.* All operational parts of a harrow should loosen soil at equal depth. Harrowed soil surface should be even. During operation, the harrow should move in a direct line; when operating in crops, it should not damage cultivated plants.

#### *3.2.2. Harrow classification and construction*

*Turning ploughshares* (Figure 23 g) are made of a handle and a tippler. They may be left- or right-sided, used for operation in row-spacing of potatoes or other hilling-up vegetables. These ploughshares are located at the distance of 250–270 mm on both sides of plants. They cut weed,

*Weeding rotors* (Figure 23 h) loosen soil and destroy weed in row-spacing. Working with weeding rotors, a narrower protective zone around plant rows is left. They are made of a bend rotor in respect to soil which turns around the axle fastened to the handle. On the sides of a rotor, axles are fastened to which the cultivator is mounted. During operation, cultivators turn around their axles and turn together with a rotor; so weeds are rooted out and covered with soil. If plants are lower than 50 mm, a shield is attached to the handle; the shield protects plants

*Protective convexes* (Figure 23 f) are attached above plant rows and protect them from covering with soil. They are used if plants are lower than 50 mm. Protective plates are also used to

In modern row-spacing cultivators, *cut discs* 5 (Figure 3.5) are mounted on the sides of sections in order to protect plants from being covered with soil and to shake soil off plants. When rolling, cut discs move ploughshares up and down; in this case, soil is better shaken off the

*Rotor row-spacing cultivators.* Their operational parts are rotors turning around the hori‐ zontal axle in the driving direction; knives of various forms are attached to rotors. Rotors are turned by a tractor operational shaft through gears. Width of rotors is adapted for loosening of row-spacing, the width of which is not narrower than 450 mm. The soil is hilled up by the

Row-spacing of potatoes, sugar beet and strawberries is loosened by rotor cultivators. It is not possible to use them in light soil since the structure of the soil is destroyed (many small particles are created; in rainy weather these particles form a crust). When loosening stony soil by rotor

*Purpose of harrow.* The surface of the soil is levelled and loosened, bigger clods are chopped, and soil preparation for sowing is completed. In spring, soil surface is loosened by a harrow; an isolation layer that does not allow dampness to disappear is formed. The harrow destroys springing out weed and cuts the growing ones. The harrow may also be used to insert mineral fertilizers and seeds of perennial grass and other plants. The harrow may be used for harrowing

*Requirements for agromachinery.* All operational parts of a harrow should loosen soil at equal depth. Harrowed soil surface should be even. During operation, the harrow should move in

the sprung out crop, aiming to destroy springing weed and chop-forming soil crust.

a direct line; when operating in crops, it should not damage cultivated plants.

loosen soil in the depth of 60 mm and cover weeds in the plant protection zone.

protect plants from being covered with soil (Figure 23 c).

roots of weeds, and weeds are destroyed better.

gear frame by a passive ploughshare.

row-spacing cultivators, knives break [26].

*3.2.1. Purpose of harrow and requirements for agromachinery*

**3.2. Harrow**

from covering with soil.

58 Weed Biology and Control

According to the type of operational parts, harrows are classified into rod, spring, mesh, digital, knife and rotation. According to the movement of operational parts, harrows are classified into passive with crawling operational parts, rotational with turning operational parts and active. Active harrows have obligatory flashing to the sides of the operational parts, and a rotor with obligatory turning operational parts.

According to purpose, harrows may be used for pre-sowing and post-sowing harrowing. For pre-sowing harrowing, heavy- or average-weight harrows are used. Cultivation of clay and loamy soil tilled by other equipment is finished by heavy harrows, and average-weight harrows are used to finish cultivation of sandy loam. Light harrows are used for post-sowing harrowing. They are used for harrowing springing beetroot, corn and other agricultural plants. Light harrows loosen soil up to 5 cm, average-weight harrows up to 7–8 cm, and heavy harrows up to 10 cm deep.

According to harrowing direction, they may be lengthwise, transversal, diagonal, or harrow‐ ing in a circle, i.e., by the field cut-out. Previously, wooden harrows were used for soil loosening. The first harrow rods were made of wood, and, later on, at the end of the seventeenth century, they became metal [29]. In Eastern Europe and Lithuania, harrows started to be used at the end of the first millennium. The oldest harrows were the top of a cut fir tree or pine tree, with cut branches 50-70 cm long. Such harrows were pulled by a human, and later by a horse or bull. Rod harrows with wooden frame and metal harrow rods started to be used in Lithuania in the end of the nineteenth century, and rod harrows with metal frame at the beginning of the twentieth century.

*Rod harrows* may be made with stiff or flexible frames. Rod harrows are made of a metal frame and harrow rods. According to the mass falling to one harrow rod, rod harrows are classified into light, average-weight and heavy. Light harrows' mass to one rod is 0.6–1.0 kg, averageweight harrows, 1.0–1.5 kg, and heavy harrows, 1.5–2.0 kg. Frames of rod harrows may be zigzag, rhombus, or more rarely S form.

*Spring harrows* are made of a stiff frame and spring rods. They are often used for pre-sowing soil cultivation. Spring rods lift couch-grass to the soil surface. It is possible to use this harrow in stony soil. Spring rods (Figure 24) are similar to the ploughshares of a continuous operation cultivator; but they are smaller, located more densely and cultivate soil more shallowly.

**Figure 24.** Spring harrow rod [26].

**The** *mesh harr***ow** (Figure 25 a) is a flexible rod harrow. It is made of separate meshes net among themselves. Meshes together with the harrow rod are bent from 8-10 mm diameter round steel wire. Rods may be 120–180 mm long, their ends pointed or obtuse. Rods of harrows meant for harrowing light soil are obtuse; for average-weight soil, flat; for heavy soil, pointed. These harrows destroy weeds, and the soil crust on crops is broken.

**Figure 25.** Mesh harrow (*a*) and harrow rods: *b* – pointed, *c* – flat; *d* – obtuse [30, 31].

*Articulated harrows* do not have a stiff frame. Separate chains of articulated harrow are flexibly connected among themselves and make an articulated net. This harrow adapts well to soil unevenness. An articulated harrow with blade rods is used for the care of meadows and pastures.

*Digital harrow* is a light harrow used for crop care. Sometimes it is used in a set with a continuous operation cultivator and seeding machines. It is made of long springing rods located in several rows. With this harrow, soil is loosened at the depth of 0.10–030 m.

Depending on soil characteristics, harrow rods may be chosen for crop harrowing accordingly (Figure 27). Thicker rods are used for heavier soils, thinner for lighter; in very stony soils, straight rods are used, and in less stony soils, bent rods are used.

*a* – for heavy soil; *b* – for stony soil; *c* – for average weight soil; *d* – for light soil; *e* – for various soils (universal) [32].

#### **Figure 26.** Harrow rods

*Rotation harrow* is made of rotors with rods turning around the horizontal (Figure 28) or vertical axle. They destroy weeds and rip the soil crust in row-spacing. A rotation harrow with a horizontal rotor is usually mounted in row-spacing cultivators. A rotation harrow with a rotor turning around the vertical axle is used for the cultivation of stony soil.

**Figure 27.** Rotation harrow [26]

**The** *mesh harr***ow** (Figure 25 a) is a flexible rod harrow. It is made of separate meshes net among themselves. Meshes together with the harrow rod are bent from 8-10 mm diameter round steel wire. Rods may be 120–180 mm long, their ends pointed or obtuse. Rods of harrows meant for harrowing light soil are obtuse; for average-weight soil, flat; for heavy soil, pointed. These

*Articulated harrows* do not have a stiff frame. Separate chains of articulated harrow are flexibly connected among themselves and make an articulated net. This harrow adapts well to soil unevenness. An articulated harrow with blade rods is used for the care of meadows and

*Digital harrow* is a light harrow used for crop care. Sometimes it is used in a set with a continuous operation cultivator and seeding machines. It is made of long springing rods

Depending on soil characteristics, harrow rods may be chosen for crop harrowing accordingly (Figure 27). Thicker rods are used for heavier soils, thinner for lighter; in very stony soils,

*a* – for heavy soil; *b* – for stony soil; *c* – for average weight soil; *d* – for light soil; *e* – for various soils (universal) [32].

*Rotation harrow* is made of rotors with rods turning around the horizontal (Figure 28) or vertical axle. They destroy weeds and rip the soil crust in row-spacing. A rotation harrow with a horizontal rotor is usually mounted in row-spacing cultivators. A rotation harrow with a

rotor turning around the vertical axle is used for the cultivation of stony soil.

located in several rows. With this harrow, soil is loosened at the depth of 0.10–030 m.

harrows destroy weeds, and the soil crust on crops is broken.

**Figure 25.** Mesh harrow (*a*) and harrow rods: *b* – pointed, *c* – flat; *d* – obtuse [30, 31].

straight rods are used, and in less stony soils, bent rods are used.

pastures.

60 Weed Biology and Control

**Figure 26.** Harrow rods

For mechanical post-sowing weed destruction (when chemical methods are not allowed) in ecological farms, a harrow made of many sections with a flexible frame, called an *ecological harrow*, may be used (Figure 26).

**Figure 28.** Ecological harrow: a means for post-sowing crop harrowing [32].

Such a harrow is light, it copies soil surface well and destroys weeds without damaging the crop. Short-age weeds are the most sensitive to harrowing by such a harrow: *Chenopodium album*, *Sinapis arvensis*, *Galeopsis tetrahit*, *Polygonum lapathifolia*, *Polygonum aviculare*, *Capsella bursa-pastoris*, *Euphorbia helioscopia,* et al. It is advisable to harrow on a clear day when the sun is shining because in such weather weeds are destroyed better. The harrow's effectiveness depends on the composition of weeds, harrow time and meteorological conditions.

#### **4. Conclusions**

Weed control is an important link in the chain of technological crop supervision. In order to perform this technological operation properly, it is important to know the characteristics of weeds and properly select technical-technological measures to destroy them. The most commonly used and most effective plant care and weed control methods are chemical (using loose and liquid chemical products) and mechanical (using agricultural implements, cultiva‐ tors and harrows). These basic weed control techniques and technologies are analysed in this educational book.

Technical-technological measures for effective plant weed control methods – chemical and mechanical – are presented. Plant protection machines using chemical products are classified into the following groups: sprayers, powder distributors, fumigators and pickling machines. Sprayers are classified according to a variety of features: power source, destination and spraying method. An important part of sprayers is the sprayer beam, which during operation has to hold the nozzles parallel to the sprayed surface so that the sprayed solution is distributed evenly. Different types of nozzles are fastened on a sprayer beam, and they are classified into a number of types: according to operational mode, nozzles are classified into hydraulic, pneumohydraulic and rotational; according to the form of the sprayed liquid, hydraulic nozzles are classified into flat-flow, cone-flow and stream, and pneumohydraulic into to flatflow and cone-flow; according to construction, rotational nozzles are classified into disc and drum, and pneumohydraulic into pressure and injection, etc. The particularities of selfpropelled hydraulic field sprayer construction and operation are described in this book, too.

Weeds may be automatically recognized in two ways: by optical-electronic sensors measuring the reflecting light spectrum, and by using digital video cameras and handling systems for the filmed views. Some schemes are presented and discussed: the weed distribution scheme of optical-electronic sensors using the weed recognition system Detectspay®; an equipment scheme in which views filmed by the video camera are used for weed recognition; maps of crop weeding and spraying and a sprayer control scheme according to a crop spraying map; the ultrasound sensor P3, attached to a field sprayer's beam for precise plant protection, and the OptRx sensors for plant optical analysis, which are used to research the optical peculiarities of the cultivated plants. These sensors measure the reflected rays in the infrared and red spectra ranges.

For weed control by mechanical means, two groups of machinery can be used – cultivators and harrows. Cultivators are classified as continuous soil operation, hard and row-spacing. They may have passive or rotating operational parts. Constructions and operational parts of continuous operation and row-spacing cultivators are presented and described. Harrows can be classified according to the type of operational parts – into rod, spring, mesh, digital, knife and rotation; according to purpose, harrows may be used for pre-sowing and post-sowing harrowing; according to harrowing direction, they may be classified as lengthwise, transversal, diagonal and harrowing in a circle, i.e., by the field cut-out. Various constructions and operational parts of harrows can be used for weed control: rod harrows, spring harrows, mesh harrows and harrow rods, articulated, digital and rotation harrows, and ecological harrows for post-sowing crop harrowing.

#### **Author details**

Algirdas Jasinskas\* , Dainius Steponavičius, Povilas Šniauka and Remigijus Zinkevičius

\*Address all correspondence to: algirdas.jasinskas@asu.lt

Institute of Agricultural Engineering and Safety, Faculty of Agricultural Engineering, Aleksandras Stulginskis University, Kaunas-Akademija, Lithuania

#### **References**

into the following groups: sprayers, powder distributors, fumigators and pickling machines. Sprayers are classified according to a variety of features: power source, destination and spraying method. An important part of sprayers is the sprayer beam, which during operation has to hold the nozzles parallel to the sprayed surface so that the sprayed solution is distributed evenly. Different types of nozzles are fastened on a sprayer beam, and they are classified into a number of types: according to operational mode, nozzles are classified into hydraulic, pneumohydraulic and rotational; according to the form of the sprayed liquid, hydraulic nozzles are classified into flat-flow, cone-flow and stream, and pneumohydraulic into to flatflow and cone-flow; according to construction, rotational nozzles are classified into disc and drum, and pneumohydraulic into pressure and injection, etc. The particularities of selfpropelled hydraulic field sprayer construction and operation are described in this book, too.

Weeds may be automatically recognized in two ways: by optical-electronic sensors measuring the reflecting light spectrum, and by using digital video cameras and handling systems for the filmed views. Some schemes are presented and discussed: the weed distribution scheme of optical-electronic sensors using the weed recognition system Detectspay®; an equipment scheme in which views filmed by the video camera are used for weed recognition; maps of crop weeding and spraying and a sprayer control scheme according to a crop spraying map; the ultrasound sensor P3, attached to a field sprayer's beam for precise plant protection, and the OptRx sensors for plant optical analysis, which are used to research the optical peculiarities of the cultivated plants. These sensors measure the reflected rays in the infrared and red spectra

For weed control by mechanical means, two groups of machinery can be used – cultivators and harrows. Cultivators are classified as continuous soil operation, hard and row-spacing. They may have passive or rotating operational parts. Constructions and operational parts of continuous operation and row-spacing cultivators are presented and described. Harrows can be classified according to the type of operational parts – into rod, spring, mesh, digital, knife and rotation; according to purpose, harrows may be used for pre-sowing and post-sowing harrowing; according to harrowing direction, they may be classified as lengthwise, transversal, diagonal and harrowing in a circle, i.e., by the field cut-out. Various constructions and operational parts of harrows can be used for weed control: rod harrows, spring harrows, mesh harrows and harrow rods, articulated, digital and rotation harrows, and ecological harrows

, Dainius Steponavičius, Povilas Šniauka and Remigijus Zinkevičius

Institute of Agricultural Engineering and Safety, Faculty of Agricultural Engineering,

ranges.

62 Weed Biology and Control

for post-sowing crop harrowing.

\*Address all correspondence to: algirdas.jasinskas@asu.lt

Aleksandras Stulginskis University, Kaunas-Akademija, Lithuania

**Author details**

Algirdas Jasinskas\*

