**8. Weed control**

*Multifunctionality and Impacts of Organic and Conventional Agriculture*

**7. Furrowing, fertilization, and planting of sugarcane**

distribution of plants, more uniform soil cover and increased yields.

losses by leaching of both nitrogen and potassium can be found in Ref. [1].

, while total N contents were 0.7, 0.4, and 0.3 g kg<sup>−</sup><sup>1</sup>

N would be enough to satisfy the needs of the plant-cane.

The lack of response of the plant-cane to nitrogen fertilization is due to the mineralization of soil organic matter and the greater nutritional efficiency of the plant-cane root system, compared to the regrowth [1, 4]. Studies conducted by Ref. [11] in the coastal plains of Pernambuco (Northeast Brazil) provide more information regarding the mineralization of soil organic matter. These authors measured carbon and nitrogen mineralization in a Red Yellow Podzolic during the plant-cane cycle. The soil was sampled at 0–20, 20–40, and 40–60 cm prior to planting and 3, 6, 11, and 16 months after planting. Total carbon contents were 6.7, 4.1, and

and 40–60 cm, respectively. The estimated amounts of potentially mineralizable N were 139 and 132 kg per ha at 0–20 and 20–60 cm, respectively, with a mineralization constant of 0.074 per week. Ref. [11] also report that although the soil is considered of low fertility based on the results, the amounts of mineralized organic

Nitrogen uptake and metabolism are strongly influenced by the endogenous availability of phosphorus [1, 12, 13]. In plants with adequate P supply, there is an increase in nitrate uptake from the soil solution and greater nitrate translocation from roots to shoots, increasing the accumulation of amino acids in leaves and roots [4, 12, 14]. Ref. [4] reported research conducted in the state of Minas Gerais, in which the increase of the dose of phosphate fertilization applied in the planting furrow resulted in higher N accumulation in the biomass of the plant-cane. In this

at 0–20, 20–40,

biological fixation and accumulation by the plant.

inoculation of the seeds of *Crotalaria juncea* will not result in increased nitrogen

Furrowing the soil for the planting of sugarcane is done after plowing and harrowing the land for the incorporation of limestone and gypsum or, after the incorporation of *Crotalaria juncea* in "one-and-a-half-year sugarcane". Furrowing is typically done with fertilizer furrowers that simultaneously open furrows and fertilize. When this implement is not available, it is possible to use a plow with moldboards or discs, using a single disc (straight furrowing if possible). Furrowing should be carried out as close as possible to the distribution of seedlings and planting rows to conserve soil moisture on dry days or avoid the silting of the furrows on rainy days. The spacing between furrows has varied from 0.90 to 1.40 m depending on the distance between the tires of the implement used in the crop fields, on topography, on soil fertility, and on the type of crop. In more fertile areas, wider spacing is used to prevent the sugarcane from tapering and future toppling by the wind. On the other hand, in soils with lower fertility, less fertilized, and on sloped relief, or when cultivars with lower tillering capacity are used, narrower spacing should be used to allow better spatial

The recommended fertilization of the plant-cane is based on the results of the soil analysis at 0–20 cm and the expected yield of the sugarcane plantation. For plantcane, only phosphate and potassium fertilization are recommended, because studies conducted by the authors of the chapter showed a lack of response to nitrogen fertilization. This low or absent response of the plant-cane to fertilization is widespread for soils grown with sugarcane in Brazil [4]. For the typically low fertile soils of the Zona da Mata region, the recommendation is 100 kg of phosphorus and 200 kg of potassium per ha (equivalent to 229 of P2O5 and 240 kg of K2O per ha). If gypsum is applied to the soil, triple superphosphate should be used to reduce the planting costs, as it is less expensive. More information on fertilizer doses and soil fertility, as well as

**30**

3.4 g kg<sup>−</sup><sup>1</sup>

Weeds compete with sugarcane during the growth phase for water, light, nutrients, and may exude phytotoxic compounds (allelopathy) and host pests and diseases [4, 15]. Sugarcane exhibits C4 metabolism, which makes it relatively more competitive in CO2 assimilation and nutrient use. However, several weeds are from the same family as is sugarcane and therefore have the same metabolism. At the time of harvest, the presence of weeds continues to cause damage, because when sugarcane is cut by hand and without previous burning, the presence of weeds decreases the workers' efficiency and makes them more vulnerable to snake and scorpion bites. The longevity of the sugarcane plantation also decreases when weed control is not effective. In most cases, keeping the crop free from competition with weeds until the vegetation closes the spacing between the rows ensures the harvest of sugarcane without the presence of weeds.

There are several techniques used for weed management. However, the combined use of cultural, mechanical, and chemical methods is the most common [4, 15]. Cultural methods are practices that aim to make sugarcane crop more competitive in relation to weeds and include reducing planting space, intercropping or crop rotation with soybean, peanut, corn, and green manure, as well as the use of high-tillering varieties for faster shading of the soil [4, 15]. In research conducted by the authors in areas heavily infested with Brachiaria, the sowing of *Crotalaria juncea* at the time of the renewal of the sugarcane plantation had a great suppressive effect (due to shading) and reduced the number of seeds produced by the grass.

Plows and harrows are used in the mechanical control during the renewal of the sugarcane plantation. This method is highly efficient, but depends on soil moisture, solar radiation and the predominant species in the area. For weed control between the rows of sugarcane, animal traction plows can be used. Manual weeding, once used, has now been restricted to experimental areas. Mechanical cultivation has limitations, especially because it does not control the weeds of crop rows. Its efficiency in controlling weeds between crop rows may also be greatly reduced depending on the climatic conditions and species, such as some grasses of the *Brachiaria* genus, which reproduce vegetatively. The chemical method has been the most used by small producers (**Figure 4**), with herbicides being used in preemergence or postemergence of weeds and with those in early or developed stages (**Table 6**).

Below are some considerations about herbicides commonly used in sugarcane cultivation.

**Figure 4.**

*The use of herbicides to maintain the crop free from weed competition until the space between rows is closed generally guarantees sugarcane harvest without the presence of weeds.*

*Ametryn*: recommended in pre- or early postemergence application, alone or mixed with other herbicides (diuron, 2,4-D, Tebuthiuron, Clomazone, Monosodium methyl arsenate (MSMA), and others). This herbicide causes little toxicity to the sugarcane crop. The effective control period or residual effect is about 70–100 days. It is effective in controlling *Digitaria horizontalis*, *Brachiaria plantaginea*, *Eleusine indica*, *Portulaca oleracea*, *Amaranthus spp*, *Bidens pilosa* and *Acanthospermum hispidum*. Doses vary from 3.0 to 5.0 L/ha. The smaller doses are recommended for lighter soils or application in moist soil, while higher doses should be used in heavy soils or application in dry soils.

*2,4-D*: recommended for post-emergence application, alone or mixed with other herbicides (Diuron, MSMA, Tebuthiuron, Ametryn, and others). The effective control period is 25–40 days. It is effective only in the control of dicotyledons. Doses vary from 0.8 to 1.5 l per ha.

*Diuron*: Recommended in pre- or early postemergence application, alone or mixed with other herbicides (2,4-D, Tebuthiuron, MSMA, and others). It has a residual effect of 150 to 180 days. It is effective in the control of *Digitaria horizontalis*, *Brachiaria plantaginea*, *Eleusine indica*, *Portulaca oleracea*, *Amaranthus spp*, *Bidens pilosa*, *Bidens pilosa* and *Acanthospermum hispidum*. Doses range from 1.8 L/ ha (Diuron 500) to 3.2 L/ha (Karmex GRDA).

*Diuron + Hexazinone*: sold under the names Advance and Velpar K. Advance is mostly used in plant-cane and Velpar K in regrowth. Both are applied in pre- or early postemergence in moist soil. They may cause toxicity to the crop, especially in sandy soils and in conditions of high moisture content. It has broad spectrum of control and residual effect of 90–120 days. It is efficient in controlling *Panicum maximum* jacq. Cv.Colonião, this is a very present and competitive species in the cultivation of sugar cane. The doses of Advance and Velpar K vary from 2.2 to 2.8 and 1.5 to 2.7 kg/ha, respectively.

**33**

**Table 6.**

*MSMA*: recommended for late postemergence in direct spray application. It causes high toxicity to the sugarcane crop. It has been widely used in mixtures with other herbicides (Diuron, 2,4-D, Tebuthiuron, Ametryn, Velpar K, and others). It is effective in the control of several annual and perennial grasses, as well as nutsedge when it has

about 4–8 leaves. Doses of 0.5–0.87 L/ha are recommended for MSMA 790.

*Sugarcane Production Systems in Small Rural Properties DOI: http://dx.doi.org/10.5772/intechopen.84975*

*Membrane disrupters*

*Inhibitors of photosynthesis*

*Inhibitors of mitosis and early growth*

*Inhibitor of respiration*

*Inhibitors of amino acid synthesis*

*Inhibitors of pigment synthesis*

*Growth regulators*

**Action mechanism Application time Herbicide (Brand)**

Sulfentrazone Preemergence Boral and Solara

Ametryn Pre- or postemergence Ametryn, Gesapax, Herbipax, and

Atrazine Pre- or post-emergence Atrazinex, Gesaprim, Atrazine, and

Atrazine + Simazine Pre- or postemergence Extrazin, Triamex, Primatop, and

Diuron Pre- or postemergence Karmex, Diuron Nortox

Hexazinone + Diuron Pre- or postemergence Velpar K and Advance

Tebuthiuron Preemergence Combine, Tebuthiuron

MSMA Postemergence Daconate, Dessecan

Trifluralin Preemergence Trifluralina Nortox, Treflan, and

Glyphosate Postemergence Glifosato, Roundup, and Trop

Imazapyr Pre- or postemergence Arsenal, Contain e Chopper

Ametryn + Diuron Pre- or postemergence Ametron

Metribuzin Pre- or postemergence Sencor Simazine Preemergence Gesatop

Alachlor Preemergence Laço Pendimethalin Preemergence Herbadox

Flazasulfuron Pre- or postemergence Katana

Halosulfuron Postemergence Sempra Imazapic Pre- or postemergence Plateau

Trifloxysulfuron +Ametryn Postemergence Krismar

Clomazone Preemergence Gamit Isoxaflutole Preemergence Provence Clomazone + Ametryn Preemergence Sinerge, Ranger

2,4-D Pre- or postemergence DMA Dicamba Pre- or postemergence Banvel 480 Picloram +2,4-D Pre- or postemergence Dontor

*Main herbicides used in sugarcane and application times in relation to weed emergence.*

Metrimex

Nortox

Herbimix

Premerlin

Oxyfluorfen Pre- or postemergence Goal

*Multifunctionality and Impacts of Organic and Conventional Agriculture*

*Ametryn*: recommended in pre- or early postemergence application, alone or mixed with other herbicides (diuron, 2,4-D, Tebuthiuron, Clomazone, Monosodium methyl arsenate (MSMA), and others). This herbicide causes little toxicity to the sugarcane crop. The effective control period or residual effect is about 70–100 days. It is effective in controlling *Digitaria horizontalis*, *Brachiaria plantaginea*, *Eleusine indica*, *Portulaca oleracea*, *Amaranthus spp*, *Bidens pilosa* and *Acanthospermum hispidum*. Doses vary from 3.0 to 5.0 L/ha. The smaller doses are recommended for lighter soils or application in moist soil, while higher doses should

*The use of herbicides to maintain the crop free from weed competition until the space between rows is closed* 

*2,4-D*: recommended for post-emergence application, alone or mixed with other

herbicides (Diuron, MSMA, Tebuthiuron, Ametryn, and others). The effective control period is 25–40 days. It is effective only in the control of dicotyledons. Doses

*Diuron*: Recommended in pre- or early postemergence application, alone or mixed with other herbicides (2,4-D, Tebuthiuron, MSMA, and others). It has a residual effect of 150 to 180 days. It is effective in the control of *Digitaria horizontalis*, *Brachiaria plantaginea*, *Eleusine indica*, *Portulaca oleracea*, *Amaranthus spp*, *Bidens pilosa*, *Bidens pilosa* and *Acanthospermum hispidum*. Doses range from 1.8 L/

*Diuron + Hexazinone*: sold under the names Advance and Velpar K. Advance is mostly used in plant-cane and Velpar K in regrowth. Both are applied in pre- or early postemergence in moist soil. They may cause toxicity to the crop, especially in sandy soils and in conditions of high moisture content. It has broad spectrum of control and residual effect of 90–120 days. It is efficient in controlling *Panicum maximum* jacq. Cv.Colonião, this is a very present and competitive species in the cultivation of sugar cane. The doses of Advance and Velpar K vary from 2.2 to 2.8

be used in heavy soils or application in dry soils.

*generally guarantees sugarcane harvest without the presence of weeds.*

ha (Diuron 500) to 3.2 L/ha (Karmex GRDA).

vary from 0.8 to 1.5 l per ha.

**Figure 4.**

and 1.5 to 2.7 kg/ha, respectively.

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#### **Table 6.**

*Main herbicides used in sugarcane and application times in relation to weed emergence.*

*MSMA*: recommended for late postemergence in direct spray application. It causes high toxicity to the sugarcane crop. It has been widely used in mixtures with other herbicides (Diuron, 2,4-D, Tebuthiuron, Ametryn, Velpar K, and others). It is effective in the control of several annual and perennial grasses, as well as nutsedge when it has about 4–8 leaves. Doses of 0.5–0.87 L/ha are recommended for MSMA 790.

*Tebuthiuron*: recommended for preemergence, including application to dry soils. It is not efficient in postemergence application. It persists in soil for a longer period, with residual effect of 12–15 months. It should not be used in areas intended for future renewal of the sugarcane plantation and should use crop rotation with soybean, peanut, and bean. It has a broad spectrum of control, and it is efficient in controlling several dicotyledons and grasses, including *Panicum maximum* jacq. Cv. Colonião, but not efficient for *Digitaria horizontalis*.
