Total energy return Energy Output: Input Ratio= Total input involved in terms of energy

The various practices involved in crop production and economic yield of component crops in the sequences were converted into the equivalent value of chemical energy (MJ/ha). For these conversions, standard values as given by [6] were used (Table 2).


**Table 2.** Energy coefficients.

### **8. Effects of organic sources in rice based on cropping sequence**

### **8.1. Effect of weather in crops**

Total energy return Energy Output: Input Ratio= Total input involved in terms of energy

The various practices involved in crop production and economic yield of component crops in the sequences were converted into the equivalent value of chemical energy (MJ/ha). For these

> Adult men Man hours 1.96 Women Woman hours 1.57

**S. No. Particulars Units Equivalent energy (MJ/ha)**

2. Diesel Liter 56.31 3. Electricity KWH 11.93

> (a) Nitrogen Kg 60.6 (b) P2O5 Kg 11.1 (c) K2O Kg 6.7

> Granulated chemical Kg 120 Liquid chemical ml 0.102

> Potato Kg 4.06 Rice, maize Kg 14.7 Onion Kg 15.8 Cowpea, pea, rajmash Kg 14.7

> Cowpea, table pea, rajmash Kg (pod) 3.89

1. Rice Kg (dry mass) 14.7

2. Onion Kg (bulb) 2.60 3. Potato Kg (tuber) 4.06 4. Maize Kg (green cob) 4.41

conversions, standard values as given by [6] were used (Table 2).

**Input**

1. Human labor

140 Organic Farming - A Promising Way of Food Production

4. Chemical fertilizer

5. Plant protection (Superior)

6. Seeds

**Table 2.** Energy coefficients.

**Output**

Plants growing in natural environment are often prevented from expressing their full genetic potential for production as they are subjected to various biotic and abiotic stresses. Environ‐ mental factors are relatively more dynamic in determining the extent of growth and develop‐ ment of plants and play major roles in the completion of the plant life cycle. Every crop requires a definite set of environmental conditions for its proper growth and development. Matching the crop phenology to the climatic environment prevailing during the growing season is an important aspect to maximize genetic yield potential.

### **8.2. Economic yield of rice**

In organic nitrogen sources, the application of 100% RDN through organic manure along with biofertilizers recorded the highest grain yield during both years of investigation. This might be due to better availability of nutrients through superimposition of organic manure along with biofertilizers. It was also observed that plants were well supplied with nitrogen, senes‐ cence of flag leaf was delayed, and respiratory losses were low. Potassium also had expressed, in addition of CO2 assimilation rates, resulting in more supply of photosynthates along with micronutrients responsible for the effective translocation of photosynthates that probably accounted for the highest economic yield. In addition to these, *Azotobacter* produced growth promoting substances that improved seed germination and growth with extended root systems. It also produced polysaccharides that improved soil aggregation; whereas, PSB in the rhizosphere of rice rendered insoluble soil phosphate available to plants due to their produc‐ tion and secretion of organic acids, as well as due to the release of sufficient amounts of nitrogen by mineralization at a constant level, which in turn resulted in better crop growth and improvement in various yield components of rice.

### **8.3. Potato equivalent yield of winter season crops**

The maximum potato equivalent yield was recorded under the sequence rice-potato-cowpea (green pod). It may be emphasized here that PEY of crops is the function of market price along with the yield of a particular crop. The potato itself produced higher economic yield and this is accompanied with better market value as a result of potato equivalent yield that were higher as compared to other sequences. Further nitrogen application through organic manures significantly augmented the potato equivalent yield due to the continuous raising of organic potato bio-dynamically on the same site, which improved tuber production by enriching soil fertility.

### **8.4. Onion equivalent yield of summer season crops**

The maximum onion equivalent yield was recorded under the sequence rice-green pea-onion. The onion itself produced higher economic yield due to the inclusion of legume as a previous crop and this accompanied with better market value as a result of onion equivalent yield that were higher compared to other sequences. Further nitrogen application through organic manures significantly augmented the onion equivalent yield, which was due favorable growth and yield of onion crop.

### **9. Effect on quality parameters**

### **9.1. Rice**

The application of organic nitrogen also influenced protein content and protein yield due to the increase in the concentration of nitrogen in grains, which might have modified the proportion of grain constituents. The higher uptake of nutrients, particularly nitrogen, in the organic nitrogen treatments was probably responsible for the higher grain protein. Accumu‐ lation of protein in seeds may also be increased due to the continuous nitrogen supply and its translocation in seed buds and optimal nutrition. It is known that protein content imparts strength to the grain; higher protein content thus resulted in higher head rice recovery.

### **9.2. Potato**

Amongst various nitrogen substitution treatments, maximum starch content was recorded under organic sources of nitrogen along with biofertilizers, especially due to higher concen‐ tration of potassium in poultry manure, which might have modified the proportion of tubers constituents with respect to starch.

### **9.3. Onion**

Application of organic nitrogen significantly increased the allyl-propyl-disulphide and carbohydrate content (%) in onion bulbs might be due to increased volatile fatty oil content resulting in significantly higher production of allyl-propyl-disulphide in onion bulbs. In‐ creased allyl-propyl-disulphide content with increasing organic nitrogen application was in close agreement with findings of [7, 8].

### **10. System analysis**

### **10.1. Rice Grain Equivalent Yield (RGEY)**

The maximum RGEY was recorded under the sequence rice-potato-onion. The higher pro‐ duction potential of potato and onion and better market prices were instrumental for attaining higher REY by this sequence [9, 10]. Rice equivalent yield is directly associated with the yield of respective crops in the sequence and so organic manure alone or along with biofertilizers enhanced the yield potential of crops, which ultimately increased the rice equivalent yield of the sequence.

### **10.2. Production efficiency**

The sequence rice-potato-onion had recorded maximum production efficiency compared to the rest of the treatments and this was due to the better market price of potato and onion in the sequence [11]. Organic manures along with bio-fertilizers recorded the significantly highest production efficiency of the system and this was due to the highest rice grain equivalent yield of crops in the system.

### **10.3. Energetics**

were higher compared to other sequences. Further nitrogen application through organic manures significantly augmented the onion equivalent yield, which was due favorable growth

The application of organic nitrogen also influenced protein content and protein yield due to the increase in the concentration of nitrogen in grains, which might have modified the proportion of grain constituents. The higher uptake of nutrients, particularly nitrogen, in the organic nitrogen treatments was probably responsible for the higher grain protein. Accumu‐ lation of protein in seeds may also be increased due to the continuous nitrogen supply and its translocation in seed buds and optimal nutrition. It is known that protein content imparts strength to the grain; higher protein content thus resulted in higher head rice recovery.

Amongst various nitrogen substitution treatments, maximum starch content was recorded under organic sources of nitrogen along with biofertilizers, especially due to higher concen‐ tration of potassium in poultry manure, which might have modified the proportion of tubers

Application of organic nitrogen significantly increased the allyl-propyl-disulphide and carbohydrate content (%) in onion bulbs might be due to increased volatile fatty oil content resulting in significantly higher production of allyl-propyl-disulphide in onion bulbs. In‐ creased allyl-propyl-disulphide content with increasing organic nitrogen application was in

The maximum RGEY was recorded under the sequence rice-potato-onion. The higher pro‐ duction potential of potato and onion and better market prices were instrumental for attaining higher REY by this sequence [9, 10]. Rice equivalent yield is directly associated with the yield of respective crops in the sequence and so organic manure alone or along with biofertilizers enhanced the yield potential of crops, which ultimately increased the rice equivalent yield of

and yield of onion crop.

**9.1. Rice**

**9.2. Potato**

**9.3. Onion**

**9. Effect on quality parameters**

142 Organic Farming - A Promising Way of Food Production

constituents with respect to starch.

close agreement with findings of [7, 8].

**10.1. Rice Grain Equivalent Yield (RGEY)**

**10. System analysis**

the sequence.

The maximum energy input was recorded in the rice-potato-onion sequence. The energy consumed by the potato through fertilizer, seeds, and human labor and that of the onion for irrigation (electricity) and inter-culture operations resulted in higher energy input. The energy involved in N fertilizer was particularly higher in sequences involving potato and onion, which relatively consumed a large proportion of energy in seeds. The pooled data indicated that the maximum gross energy output, net energy return, and employment generation was obtained in the rice-potato-onion sequence. This clearly exhibited that besides having more energy input, this sequence also produced the highest energy equivalent, resulting into maximum gross energy output, net energy return, and employment generation [12]. In general, the gross energy output, net energy return, and employment generation of the system remained comparatively higher during the second year than that of the first year. Application of nitrogen through organic manures along with bio-fertilizers recorded maximum average energy input, gross energy output, net energy return, and employment generation of the system because this sequence was more input intensive as well as had the highest productivity level.

### **10.4. Economics**

Data related to economics as affected by various cropping sequences and organic nitrogen treatments of two years of experimentation are presented. The maximum cost of cultivation, gross return, net return, and profitability was recorded under the sequence rice-potato-onion, which was significantly higher than that of the other sequences. This was mainly due to the higher production potential of potato, accompanied with good monetary return from the onion. The highest values of cost of cultivation, gross return, net return, and profitability were associated with the application of nitrogen through organic manures along with biofertilizers. This was mainly due to higher productivity without a proportionate increase in the cost of cultivation.

### **10.5. Nutrient uptake**

Nutrient uptake by different cropping sequences is the function of crop yield and nutrient content. The increase in these factors was responsible for the increased nutrient uptake during both years of experimentation of the system, which was at the maximum under the ricecowpea-maize sequence. This was significantly superior to the rest of the sequences in this respect, which could be a higher productivity potential of maize ascribed to the increase in the available nitrogen, phosphorus, potassium, sulfur, zinc, iron, copper, and manganese contents in the soil resulting from the increased availability of nutrients through organic sources particularly through organic manure along with biofertilizers.

### **10.6. Soil fertility status**

Data on the nutrient status of soil organic carbon, major (nitrogen, phosphorus potassium), secondary (sulfur), and micronutrients (zinc, iron, copper, and manganese), recorded maxi‐ mum improvement, in this respect, was observed where pulse crops were incorporated in the sequence. Application of either organic manure alone or with biofertilizers significantly improved the soil status with respect to organic carbon and nutrients under study. It is quite obvious that this might have added greater organic sources and biofertilizer to the soil, ultimately improving the soil's organic carbon. Similarly, [13] also reported that 100% nitrogen (1/3 each from cow dung manure, neem cake, and composed crop residue) appreciably increased the organic carbon (6.3 g kg-1) over the initial value (5.8 g kg-1).

### **10.7. Soil health**

The application of organic manure along with biofertilizer significantly improved soil pH, as well as electrical conductivity was associated with the decline in soil reaction might be due to organic compounds added to the soil in the form of organic manure and biofertilizer that produced more humus and organic acids in decomposition. The role of organics is attributed to the supply of essential nutrients by the continuous mineralization of organic manures, nutrient supplying capacity of the soil, and its favorable effect in the soil's biological (bacteria, actinomycetes and fungi) properties [14,15]

### **11. Conclusion**


(Zn, Fe, Mn, Cu) than the rest of the cropping sequences and was significantly superior to rest of the sequences.


### **Author details**

in the soil resulting from the increased availability of nutrients through organic sources

Data on the nutrient status of soil organic carbon, major (nitrogen, phosphorus potassium), secondary (sulfur), and micronutrients (zinc, iron, copper, and manganese), recorded maxi‐ mum improvement, in this respect, was observed where pulse crops were incorporated in the sequence. Application of either organic manure alone or with biofertilizers significantly improved the soil status with respect to organic carbon and nutrients under study. It is quite obvious that this might have added greater organic sources and biofertilizer to the soil, ultimately improving the soil's organic carbon. Similarly, [13] also reported that 100% nitrogen (1/3 each from cow dung manure, neem cake, and composed crop residue) appreciably

The application of organic manure along with biofertilizer significantly improved soil pH, as well as electrical conductivity was associated with the decline in soil reaction might be due to organic compounds added to the soil in the form of organic manure and biofertilizer that produced more humus and organic acids in decomposition. The role of organics is attributed to the supply of essential nutrients by the continuous mineralization of organic manures, nutrient supplying capacity of the soil, and its favorable effect in the soil's biological (bacteria,

**1.** The inclusion, of the two high-value vegetable crops in sequence having 300%, rice-potatoonion had the highest rice equivalent grain yield, production efficiency, net energy return, as well as net monetary return and profitability. However, the best benefit ratio was highest in the sequence rice-potato-cowpea (green pod). Thus, rice-potato-onion was observed as the most intensive, stable, and profitable high-value cropping sequence for

**2.** The organic N nutrition of organic manuring with biofertilizers had the highest rice equivalent grain yield, production efficiency, net energy return, as well as net monetary

**3.** The different cropping sequences of rice did not differ with respect to yield and quality parameters. However, the organic N nutrition with organic manures along with biofer‐ tilizers proved significantly superior with respect to the yield and quality parameters of

**4.** The different cropping sequences of rice differ with respect to nutrient uptake, i.e., ricemaize-onion had the highest removal of major (N, P, K), secondary (S), and micronutrients

return and profitability on rice-based cropping sequence.

particularly through organic manure along with biofertilizers.

increased the organic carbon (6.3 g kg-1) over the initial value (5.8 g kg-1).

**10.6. Soil fertility status**

144 Organic Farming - A Promising Way of Food Production

**10.7. Soil health**

**11. Conclusion**

irrigated ecosystems.

rice, potato, and onion.

actinomycetes and fungi) properties [14,15]

Sanjay Kumar Yadav\* , Subhash Babu, Gulab Singh Yadav, Raghavendra Singh and Manoj Kumar Yadav

\*Address all correspondence to: sanjaybhu05@rediffmail.com

ICAR-Central Potato Research Station, Upper Shillong, Meghalaya, India

### **References**


edited by Tandon, H.L.S., Fertilizer Development and Consultation Organization, pp. 49-82.


### **Potatoes (***Solanum tuberosum* **L.)**

Petr Dvořák, Jaroslav Tomášek, Karel Hamouz and Michaela Jedličková

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/61552

### **Abstract**

edited by Tandon, H.L.S., Fertilizer Development and Consultation Organization,

[6] Sriram, C.; Thyagraj, C.R.; Mayande, V.M.; and Srinivas Rao, P. (1999). Indo-U.S. Project on Research of Dryland Agriculture (Operation Search). Central Research

[7] Singh, B.; Singh, Y.; and Meelu, O.P. (1996). Management of soil organic matter for maintained productivity in rice-wheat in India. In: Studies in Indian Agro-ecosys‐

[8] Yadav R.L.; Dwivedi, B.S.; and Pandey, P.S. (2000). Rice-wheat cropping system: As‐ sessment of sustainability under green manuring and chemical fertilizer inputs. *Field*

[9] Sharma, R.P.; Pathak, S.K.; Haque, M.; and Raman, R.R. (2004). Diversification of tra‐ ditional rice (*Oryza sativa*) based cropping system for sustainable production in south

[10] Yadav, M.P.; Rai, J.; Kushwaha, S.P.; and Singh, G.K. (2005). Production potential and economic analysis of various cropping systems for central plains zone of Uttar

[11] Saroch, K.; Bhargava, M.; and Sharma, J.J. (2005). Diversification of existing rice (*Ory‐ za sativa*) based cropping system for sustainable productivity under irrigated condi‐

[12] Newaj, Ram and Yadav, D.S. (1992) Production potential and labour employment under different cropping system under upland conditions of eastern Uttar Pradesh.

[13] Urkurkar, J.S; Chitale, S.; and Tiwari, F. (2010). Effect of organic v/s chemical nutrient packages on productivity, economics and physical status of soil in rice–potato crop‐

[14] Hati, K.M.; Mandal, K.G.; Mishra, A.K.; Ghosh, P.K.; and Acharya, C.L. (2001). Effect of irrigation regimes and nutrient management on soil water dynamics, evapo-tran‐ spiration and yield of wheat in vertisols. *Indian Journal of Agricultural Sciences*, 71(9):

[15] Wu, S.; Ingham, E.; and Hu, D. (2002). In: 17th World Congress of Soil Science, Queen Sirkit National Convention Centre, 14-21 August 2002, Bangkok, Thailand, Abstract

tems (Pathak, P.S. and Gopal, B. eds.), National Institute of Ecology, p. 85-90.

Instt. for Dryland Agriculture, Hyderabad, India. *Annexure I*.

Bihar alluvial plains. *Indian J. Agron*., 49(4): 218-222.

ping system in Chhattisgarh. *Indian J. Agron*., 55 (1): 6-10

Pradesh*. Indian J. Agron*., 50(2): 83-85.

tions. *Indian J. Agron.*, 50(2): 86-88.

*Indian J. Agron*., 37(3): 401-406.

581-587.

Vol. V, p. 1756.

pp. 49-82.

146 Organic Farming - A Promising Way of Food Production

*Crops Res*., 65: 15-30.

In the area of potato production, targeted research solving concrete and actual problems of potato producers runs on Czech University of Life Sciences in Prague. In the last few years, we were focused on the production of new potatoes designated for early harvest, and we were focused on capitalization of yielding and qualitative characteristics of col‐ ored potato variety. These findings were further utilized and transferred to the system of organic farming. Firstly, we watched the influence of organic farming on yield and quali‐ ty of tubers. Ecological ways of cultivation had strong negative influences on yield (de‐ crease of 36%). From qualitative characteristics, organic farming increased the content of polyphenols by 10.2%, decreased the content of nitrates by 11.0%, and decreased the con‐ tent of reducing sugars by 22.0%. We also evaluated the possibilities and impacts of mulch on potato cultivation. The mulch on top of ridges affected the temperature of soil (it increased the temperature by 0.2–0.6 °C under black mulching nonwoven fabric, and it decreased by 0.5–0.8 °C under herbal mulch). The mulch also affected soil humidity (herbal mulch decreased the soil humidity) and adjust weed infestation (20 to 92% lower), soil erosion (95% lower), the occurrence of Colorado beetle (the number of larvae was 22.8% lower with herbal mulch and 88.7% higher with mulching textile), and late blight in potato vegetation.

**Keywords:** Potatoes, organic farming, mulching, plant extracts, quality tubers

### **1. Introduction**

Potatoes in Czech Republic belong to the minority crops cultivated in the system of organic farming. Like the principal tuber crop, it forms ca. 0.5% of the whole certified area of Czech Republic. The area of consumption potatoes actuate over is an area of 200 ha (in 2012, 3,277 tonnes of organic potatoes were harvested on an area of 230 ha).

Cultivating potatoes organically is very demanding on producers. Producers must deal with the absence of chemicals used on crop protection, the absence of synthetic fertilizers, the

© 2016 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 reproduction in any medium, provided the original work is properly cited.

obtainment of acceptable yield and good quality of tubers, and the necessity of applying all the procedures to create suitable conditions for growth and development of crops, like any other crop cultivated organically [1].

### **2. Environmental conditions**

The potatoes originate from the mountain area that is why the foothill conditions suit them well. The optimum amount of precipitations for potatoes is 650 to 800 mm annually (60– 70% of this amount during the vegetation). The precipitations during the first half of vegetation influence the growth of tops, the precipitations from May to half of July influence the number of tubers under the clump (with consideration of the time of planting and earliness of the variety). The precipitations in the second half of vegetation determine the weight of tubers. The deficiency of precipitations during the period of planting until emergence relatively positively affects the yield of tubers. Plants produce more roots and can manage water better [1].

In case of early potatoes, where the well-timed soil preparation and well-timed planting is important (it occurs until the end of April in the Czech Republic), we choose the fields with soil easily processed early in the spring. From the point of view of the regulation of fungi diseases, we prefer the open fields (air locations which provide quick drying of plants). The good choice of location can regulate the occurrence of late blight [2].

### **3. Choice of suitable variety**

Like any other crops, the choice of variety in the system of organic farming is crucial. The quality and health conditions of chosen planting material are vital, too. Generally recom‐ mended are the varieties with shorter vegetation period (with quicker initial growth and quicker tuber formation), lower nitrogen requirements, and higher resistance against diseases [2]. In case of varieties with longer vegetation period (usually intended for autumn consump‐ tion and storage), it is important to choose varieties highly resistant against late blight [3].

The choice of variety is submitted to the purpose of production (direct consumption, washing or peeling, on food-processing products such as chips and potato puree). For the consumer varieties, the determining aspects are qualitative indexes expressed by table value. It is commonly expressed by so-called cooking type of tubers (based on evaluation of consistency of cooked tubers, moisture, structure, mealiness, darkening, and taste). For this purpose are potato varieties divided into four groups: (1) cooking type A – consistent, tallowy, of delicate to semi-delicate structure, cannot be overcook, very weakly to weakly farinaceous tubers (suitable for preparation of potato salads or for meals when it is necessary to keep the shape even after cooking, like in case of soups, and for common consumption); (2) cooking type B – semi-consistent, semi-farinaceous, pleasantly moist to dry (suitable generally as a side dish); (3) cooking type C – soft, farinaceous tubers, semi-moist to dry (suitable mainly for preparation of purees, potato dough, and potato pancakes); (4) cooking type D – rough, strongly farina‐ ceous, and can be overcooked (undesirable for consumption purposes, usable for starch processing or for other products).

Until the present, no compact information is available in Czech Republic concerning the comparison of potato varieties in the system of organic farming.

The colored varieties are an interesting area for organic farming. They are more frequent in organic farms abroad. There is a speciality from the viewpoint of both appearance (colorfulness and shape of tubers) and nutritional value (mainly the high content of antioxidants and pigments). This area has been, in the long term, intensively examined by Prof. Ing. Karel Hamouz, CSc. and his colleagues from the Faculty of Agrobiology, Food and Natural Resour‐ ces, Czech University of Life Sciences (CULS) in Prague. Their studies are deepening the known information about these varieties (antioxidant activity, content of anthocyanin in raw and cooked tubers). It is possible to find between them perspective varieties usable for the consumption or processing (production of natural dye agents or syrups). To this group belongs variety Valfi, which originates in Czech Republic (violet variety bred in Potato Research Institute Havlíčkův Brod).

### **4. Innovations in cultivation techniques**

### **4.1. Nutrition and fertilization**

obtainment of acceptable yield and good quality of tubers, and the necessity of applying all the procedures to create suitable conditions for growth and development of crops, like any

The potatoes originate from the mountain area that is why the foothill conditions suit them well. The optimum amount of precipitations for potatoes is 650 to 800 mm annually (60– 70% of this amount during the vegetation). The precipitations during the first half of vegetation influence the growth of tops, the precipitations from May to half of July influence the number of tubers under the clump (with consideration of the time of planting and earliness of the variety). The precipitations in the second half of vegetation determine the weight of tubers. The deficiency of precipitations during the period of planting until emergence relatively positively affects the yield of tubers. Plants produce more roots and

In case of early potatoes, where the well-timed soil preparation and well-timed planting is important (it occurs until the end of April in the Czech Republic), we choose the fields with soil easily processed early in the spring. From the point of view of the regulation of fungi diseases, we prefer the open fields (air locations which provide quick drying of plants). The

Like any other crops, the choice of variety in the system of organic farming is crucial. The quality and health conditions of chosen planting material are vital, too. Generally recom‐ mended are the varieties with shorter vegetation period (with quicker initial growth and quicker tuber formation), lower nitrogen requirements, and higher resistance against diseases [2]. In case of varieties with longer vegetation period (usually intended for autumn consump‐ tion and storage), it is important to choose varieties highly resistant against late blight [3].

The choice of variety is submitted to the purpose of production (direct consumption, washing or peeling, on food-processing products such as chips and potato puree). For the consumer varieties, the determining aspects are qualitative indexes expressed by table value. It is commonly expressed by so-called cooking type of tubers (based on evaluation of consistency of cooked tubers, moisture, structure, mealiness, darkening, and taste). For this purpose are potato varieties divided into four groups: (1) cooking type A – consistent, tallowy, of delicate to semi-delicate structure, cannot be overcook, very weakly to weakly farinaceous tubers (suitable for preparation of potato salads or for meals when it is necessary to keep the shape even after cooking, like in case of soups, and for common consumption); (2) cooking type B – semi-consistent, semi-farinaceous, pleasantly moist to dry (suitable generally as a side dish); (3) cooking type C – soft, farinaceous tubers, semi-moist to dry (suitable mainly for preparation

good choice of location can regulate the occurrence of late blight [2].

other crop cultivated organically [1].

148 Organic Farming - A Promising Way of Food Production

**2. Environmental conditions**

can manage water better [1].

**3. Choice of suitable variety**

The need of nutrients, specifically the plant uptake, is given by the level of yield of tubers. Potatoes need, in average, 80–130 kg of Nitrogen per hectare (it is possible to count the uptake of 40–50 kg of Nitrogen, 8.8 kg of Phosphorus, 22 kg of Potassium, and 8.4 kg of Magnesium per 10 tonnes of tubers). This need is covered by applied barnyard manure, green manure, compost, cattle slurry, or digestate. Then the level of available nutrients depends on the level of biologic activity of the soil, i.e., mineralization conditions (which are supportable by hoeing). It is also possible to enhance the biological procedures in soil by many preparations on the basis of nitrogen fixators such as Azoter or AlgaSoil-natural organic fertilizer made of seaweed. These preparations were tested in small-plot experiments on CULS's land.

### *4.1.1. Experimental verification*

Azoter was applied by spraying a dose of 10 liters per hectare to the furrows during handplanting. AlgaSoil was applied to the furrows near tubers in a dose of 70 kg per hectare during planting. During vegetation, the content of chlorophyll was measured by hand using the Chlorophyll Meter SPAD 502 (in five terms from the 56th to the 100th day after planting), and in case of preparation, AlgaSoil leaf samples were taken twice for analyses of nitrogen and other nutrients. After harvest, tubers were sorted by size into two groups (tubers under 4 cm and over 4 cm).

The application of Azoter supported nitrogen fixation in the soil, thanks to the three genus of nonsymbiotic bacteria contained in this preparation (*Azotobacter chroococcum*, *Azospirillum* *braziliense*, and *Bacterium megatherium*). This was also shown in plants with higher chlorophyll content in their leaves (Figure 1). The application of Azoter had positive effect on the yield of tubers that was higher by 1.1 t per hectare in comparison with untreated control (Figure 2).

**Figure 1.** Chlorophyll content in potato leaves of Katka varieties in 2013 when measured by Chlorophyll Meter SPAD 502.

**Figure 2.** The final effect of Azoter on the numerical representation and weight of tubers under a clump of Katka varie‐ ty in 2013.

AlgaSoil is a natural organic granulated fertilizer based on seaweed, which should work as a soil conditioner, ameliorate the soil structure, and increase the microbial activity and the utility of nutrients in soil. AlgaSoil also increased the chlorophyll content in leaves (Figure 3).

**Figure 3.** Course content of chlorophyll in the leaves after application of the fertilizer AlgaSoil.

*braziliense*, and *Bacterium megatherium*). This was also shown in plants with higher chlorophyll content in their leaves (Figure 1). The application of Azoter had positive effect on the yield of tubers that was higher by 1.1 t per hectare in comparison with untreated control (Figure 2).

**Course of chlorophyll content in potato leaves**

18.6. 3.7. 16.7. 23.7. 1.8.

**Figure 1.** Chlorophyll content in potato leaves of Katka varieties in 2013 when measured by Chlorophyll Meter SPAD

2 3

**No. of tubers over 41 mm No. of tubers under 40 mm Weight of tubers under 40 mm Weight of tubers over 41 mm**

**Figure 2.** The final effect of Azoter on the numerical representation and weight of tubers under a clump of Katka varie‐

AlgaSoil is a natural organic granulated fertilizer based on seaweed, which should work as a soil conditioner, ameliorate the soil structure, and increase the microbial activity and the utility of nutrients in soil. AlgaSoil also increased the chlorophyll content in leaves (Figure 3).

Control Azoter (10 L per ha)

7 7

**Tubers representation**

**<sup>187</sup> <sup>176</sup> 214**

Control Azoter

**240**

0

50

100

150

**Weight of tubers (g per plant)**

200

250

300

20

0

2

4

6

**No. tubers per plant**

ty in 2013.

8

10

12

25

30

**Chlorophyll content (SPAD)**

502.

35

40

150 Organic Farming - A Promising Way of Food Production

There is known positive correlation between chlorophyll content and N content in plants [4]. The N content in variants treated by AlgaSoil (Figures 4 and 5) was 6% higher than in controls after first sampling (58th day after planting) and 24% higher after the second sampling (77th day after planting). Similarly, the chlorophyll content was higher on the 58th day by 3% as well as on the 77th day.

The AlgaSoil affected the size and final yield of tubers, which was higher by 3.6% (Figure 6).

**Figure 4.** Results of laboratory analyses on the primary nutrients content in the leaves of potatoes on the 58th day after planting [14].

**Figure 5.** Results of laboratory analyses on the primary nutrients content in the leaves of potatoes on the 77th day after planting [14].

**Figure 6.** Size analysis under a clump of tubers after treatment with AlgaSoil.

### **5. Preparation of planting material and planting**

The planting material intended for the conditions of organic farming is necessary to sprout or at least to bud. These procedures lead to lower sprout production, which means lower stalks production. This would express as lower tuber setting under the clump, but the tubers would reach the consumption size sooner. So, by these methods, we can increase the earliness and partially anticipate the decrease of production as a consequence of late blight attack. In case of early term of harvest combined with sprouting, it is possible to count the increase of yield of consumption tubers by 7–8% [8]. The disadvantage of the procedure is the increase of work requirements during biological preparations both ensuring the sprouting or budding and planting. The sprouted tubers are possible to plant only with suitable technology (potato planter or disc planting mechanism).

### **5.1. Size sorting of planting material**

Size sorting of planting material on desired size can influence the shortening of vegetation of very early varieties and their yield of tubers.

### *5.1.1. Experimental verification*

**Figure 5.** Results of laboratory analyses on the primary nutrients content in the leaves of potatoes on the 77th day after

<sup>88</sup> <sup>61</sup>

**AlgaSoil Control**

The planting material intended for the conditions of organic farming is necessary to sprout or at least to bud. These procedures lead to lower sprout production, which means lower stalks production. This would express as lower tuber setting under the clump, but the tubers would

**Over 60 mm 55-60 mm 40-55 mm Under 40 mm**

<sup>30</sup> <sup>28</sup>

**Weight representation of tubers**

99

230

112

**Figure 6.** Size analysis under a clump of tubers after treatment with AlgaSoil.

**5. Preparation of planting material and planting**

203

planting [14].

152 Organic Farming - A Promising Way of Food Production

**Weight of tugers (g per plant)**

In a precise field experiment, three sizes of planting material were compared: variant A (tubers 25 to 35 mm), variant B (tubers 40 to 60 mm), and variant C (65 to 85 mm) with the aim of finding the influence of tuber size on potato yield characteristics. In the experiment, a very early variety called Impala was used. Every variant was set in three repetitions under non‐ woven fleece textile (Pegas-agro 17 UV) and an uncovered variant was used as control. The harvest and evaluation of yield happened on the 56th to 68th day from planting.

From Table 1, we can recommend big sorting of planting material (variant C) for very early harvest of early potatoes (for regular vegetation and for vegetation covered with nonwoven fabric CFT). It was verified by papers dealing with the size of planting material [5–7] that big sorting of planting material has a marked effect on tuber yield, even on earliness of vegetation (quicker start, thanks to bigger content of energy storage molecules, and quicker ability of regeneration in case of frozen sprouts).


**Table 1.** Effect of seed tuber size on yield and yield characteristics in the stands that cultivated without cover (C) and cultivated under nonwoven fleece textile (FT) in 2005–2006

### **5.2. Pre-sprouting**

The aim of pre-sprouting is the formation of 15 to 25 mm long, colored, and firm sprouts with basis of roots. It is an intensive procedure, which can hasten emergence, vegetation growth, and even harvest [1]. From the view-point of organic farming, prepared planting materials can ensure quicker emergence of vegetation, which means better concurrence against weed. Quicker emergence also reduces the appearance of black scurf of tubers and stem canker. Presprouting is a suitable procedure to speed up tuber production, and in case of late blight and Colorado potato beetle, tubers are in late state of consumption (pre-sprouting increases the yield assurance).

### **5.3. Treatment of planting material before planting**

In conditions of organic farming, the grower has the possibility to treat potato planting material with allowed agents (this can mainly ameliorate and speed up the emergence of potatoes, than protect it against pests and diseases as in conventional cultivation). For interest, it is possible to specify some preparations, which we have tested (Albit, Amalgerol, Galleko, Special, Polyversum, Softguard). It is possible to apply these preparations on tubers before planting (ultra-low volume pesticide application of tubers in pre-shooting room) or directly during planting on the potato planter. It even partially treated the soil nearby simultaneously [1].

### **6. Treatment before emergence**

The treatment before emergence consists of ploughing and harrowing with full mechanical cultivation. The first operation after planting is blind ploughing after 7 to 10 days. In case of early potatoes, it is suitable for quicker emergence to cover less with soil or to start with harrowing (chain harrow or tine harrow for regulation of emerging weeds in phase of cotydelons). Harrowing also disturbs the soil crust, decreases the height of the top soil above the tubers (meaning warmer through the ridges), so they emerge quicker [8]. With ploughing, we destroy weeds in furrows and on the sides of ridges (it is done most frequently 7 to 10 days after harrowing).

For acceleration of vegetation and early harvest, it is possible to cover the vegetation after planting with white nonwoven fleece textile or perforated foil. The nonwoven fleece textile also provides protection against low temperature, but it limits mechanical cultivation and in case of temperatures higher than 22 °C, plants can be damaged under fleece. In an average of nine years, nonwoven fleece textile probably increased yield of tubers by 23.2% in average of years and varieties in early terms of harvest (ca. 60 days after planting) [9].

It is possible to apply mulching materials on the soil surface (on ridges) to improve soil and nutritional conditions. The main benefits of mulching materials are evaporation regulation, reduction of temperature fluctuation of the soil, and repression of weeds. They can be sources of nutrients and can limit erosion and occurrence of some pests. The right choice of suitable mulching material is important for concrete stand.

The first group are organic (herbal) mulch, such as straw, chopped grass, biomass of intercrops, or other plant material, that can be applied on the ridge surface and usually come directly from the farm. For their application, we recommend manure spreaders, separators of bales of straw, or bedding semi-trailer. The straw is used as mulch mainly abroad. It is easy to store, so it is available during the whole vegetation time [10].

The second big group of mulching materials are plastic products or other waste materials (for example, paper). Considering the origin of plastic and the impact of its application on largearea agriculture, it is necessary to reduce this material and suitably replace it. The use of biodegradable foil or black nonwoven textile can bring certain easement in this area. Targeted processing and recycling of waste paper is possible to produce paper mulching matting with different firmness and durability. The firm VUC Services (www.ekocover.cz) is engaged in this processing and production in the Czech Republic.

In connection with mulch application, it is necessary to mention that mechanical cultivation during vegetation is not possible because of the mulching fabric or foil or it may be limited (in case of plant material). However, past studies imply that the absence of cultivation has no negative effect on tuber yield.

### **6.1. Application of mulching material**

**5.2. Pre-sprouting**

154 Organic Farming - A Promising Way of Food Production

yield assurance).

after harrowing).

**5.3. Treatment of planting material before planting**

**6. Treatment before emergence**

The aim of pre-sprouting is the formation of 15 to 25 mm long, colored, and firm sprouts with basis of roots. It is an intensive procedure, which can hasten emergence, vegetation growth, and even harvest [1]. From the view-point of organic farming, prepared planting materials can ensure quicker emergence of vegetation, which means better concurrence against weed. Quicker emergence also reduces the appearance of black scurf of tubers and stem canker. Presprouting is a suitable procedure to speed up tuber production, and in case of late blight and Colorado potato beetle, tubers are in late state of consumption (pre-sprouting increases the

In conditions of organic farming, the grower has the possibility to treat potato planting material with allowed agents (this can mainly ameliorate and speed up the emergence of potatoes, than protect it against pests and diseases as in conventional cultivation). For interest, it is possible to specify some preparations, which we have tested (Albit, Amalgerol, Galleko, Special, Polyversum, Softguard). It is possible to apply these preparations on tubers before planting (ultra-low volume pesticide application of tubers in pre-shooting room) or directly during planting on the potato planter. It even partially treated the soil nearby simultaneously [1].

The treatment before emergence consists of ploughing and harrowing with full mechanical cultivation. The first operation after planting is blind ploughing after 7 to 10 days. In case of early potatoes, it is suitable for quicker emergence to cover less with soil or to start with harrowing (chain harrow or tine harrow for regulation of emerging weeds in phase of cotydelons). Harrowing also disturbs the soil crust, decreases the height of the top soil above the tubers (meaning warmer through the ridges), so they emerge quicker [8]. With ploughing, we destroy weeds in furrows and on the sides of ridges (it is done most frequently 7 to 10 days

For acceleration of vegetation and early harvest, it is possible to cover the vegetation after planting with white nonwoven fleece textile or perforated foil. The nonwoven fleece textile also provides protection against low temperature, but it limits mechanical cultivation and in case of temperatures higher than 22 °C, plants can be damaged under fleece. In an average of nine years, nonwoven fleece textile probably increased yield of tubers by 23.2% in average of

It is possible to apply mulching materials on the soil surface (on ridges) to improve soil and nutritional conditions. The main benefits of mulching materials are evaporation regulation, reduction of temperature fluctuation of the soil, and repression of weeds. They can be sources of nutrients and can limit erosion and occurrence of some pests. The right choice of suitable

years and varieties in early terms of harvest (ca. 60 days after planting) [9].

mulching material is important for concrete stand.

The experiments with herbal mulch, wheat straw, and black textile mulch (weight 50 g/m2 ) conducted from 2008 to 2012 brought many answers in the area of temperature change, soil humidity, level of material degradation, biomass of weeds, chlorophyll content in leaves, occurrence of Colorado Potato Beetle (CPB), and Late Blight on tubers and size representa‐ tion of tuber under clumps [11]. In 2014, we enlarged the experiment by other materials: biodegradable foil and two types of paper matting EkoCover (short-time matting with weight 270 g/m2 and medium-term matting with weight 800 g/m2 ).

### *6.1.1. Experimental verification*

It was found that herbal mulch functions as an isolation and during tracked time decreased the soil temperature by 0.8 °C. Mulch also affected soil humidity conditions when the lowest soaking pressure of soil (that means the highest humidity of soil) was registered at mulching textile. Soil humidity with herbal mulch was in average of years comparable to the unmulched control.

The changed humidity and temperature conditions of soil influence even the nutrient availa‐ bility in soil [12] and the whole nutritional state of vegetation within it. The source of nutrients for plants can even be its own herbal mulch. The chlorophyll content in leaves was higher by 3.7% in the case of chopped grass applied after planting or before emergence, and it was higher by 2.3% in the case of control (Figure 7). We found the lowest content of chlorophyll in leaves after using black mulching textile and straw (Figure 7 and 8). From known correlation of chlorophyll content and nitrogen content in plants [13, 14], it is possible to deduce that this vegetation had lower nitrogen content in leaves (nitrogen in soil was probably used in straw decomposition not by plants). Other mulching materials (such as paper mulching matting, biodegradable foil) applied after planting (Figure 8) induced lower chlorophyll content in leaves.

**Figure 7.** The chlorophyll content (SPAD in units) for each variant of mulch.

**Figure 8.** Chlorophyll content in experiments with biodegradable materials (Uhříněves, 2014).

Positive humidity and nutritional conditions affect even growth and biomass of weed and its regulation is ensured only by mulching fabric, biodegradable foil, and paper matting. The application of mulch (or the present weed biomass) is an effective way of soil protection against erosion because the soil is most vulnerable since the planting [15].

The mulch also affects the occurrence of CPB and the following damage of vegetation by the larvae of CPB. Chopped grass reduced the occurrence of CPB (Figure 9) and on the contrary, black mulch textile increased its attack (probably because of higher temperature of soil). The lowest occurrence was found on plots with applied straw. Similarly in 2014, the lowest occurrence of larvae was on straw and foil (Figure 10).

biodegradable foil) applied after planting (Figure 8) induced lower chlorophyll content in

36.8

C - control without mulch GM 1 - grass mulch after planting GM 2 - grass mulch before emergence BTM - black textilie mulch

**43.1**

**foils**

Positive humidity and nutritional conditions affect even growth and biomass of weed and its regulation is ensured only by mulching fabric, biodegradable foil, and paper matting. The application of mulch (or the present weed biomass) is an effective way of soil protection against

**Average chlorofphyll content (2008-2012)**

36.3

35.1

**44.5**

**Control without mulch**

**39.6**

**Straw after planting**

35.5

**Figure 7.** The chlorophyll content (SPAD in units) for each variant of mulch.

**44.6**

**Short-term mat Medium-term mat Biodegradable** 

erosion because the soil is most vulnerable since the planting [15].

**Figure 8.** Chlorophyll content in experiments with biodegradable materials (Uhříněves, 2014).

leaves.

33

**SPAD**

**43.6**

34

35

36

**SPAD**

37

38

156 Organic Farming - A Promising Way of Food Production

**Figure 9.** Dependence of the occurrence of beetles, nests with eggs and larvae of CPB on used mulching materials on station Uhříněves (2008–2012).

**Figure 10.** Dependence of occurrence of beetles, nests with eggs and larvae of CPB on used mulching materials (Uhřín‐ ěves, 2014).

**Figure 11.** Total weight of tubers, number of tubers, and yield of ware potatoes at various ways to mulching in Uhřín‐ ěves (different letters for average mean statistically significant differences at the 95% confidence level).

**Figure 12.** Total weight of tubers, number of tubers, and yield of ware potatoes at various ways to mulching in Leško‐ vice (potato growing region).

The abovementioned factors affect consequent tuber production (Figures 11, 12 and 13). The higher yield of consumption tubers was after the application of chopped grass. Yield of tubers in Uhříněves was lower after the use of black textile mulch than at non-mulched control because of the great attack and damage of vegetation by larvae of CPB. On the contrary, the positive result was achieved with textile mulch on site in the potato processing area where the occurrence of CPB was not high. Black textile mulch positively increased the temperature of the soil and water content in the soil. It produced better conditions for growth and on this site was the highest yield of consumption tubers with textile mulch (higher by 4 t/ha against control).

**Figure 13.** Yield of ware potatoes depending on the selected mulching material.

### **7. Treatment after emergence**

**Figure 11.** Total weight of tubers, number of tubers, and yield of ware potatoes at various ways to mulching in Uhřín‐

**Figure 12.** Total weight of tubers, number of tubers, and yield of ware potatoes at various ways to mulching in Leško‐

The abovementioned factors affect consequent tuber production (Figures 11, 12 and 13). The higher yield of consumption tubers was after the application of chopped grass. Yield of tubers in Uhříněves was lower after the use of black textile mulch than at non-mulched control because of the great attack and damage of vegetation by larvae of CPB. On the contrary, the positive result was achieved with textile mulch on site in the potato processing area where the occurrence of CPB was not high. Black textile mulch positively increased the temperature of the soil and water content in the soil. It produced better conditions for growth and on this site

vice (potato growing region).

158 Organic Farming - A Promising Way of Food Production

ěves (different letters for average mean statistically significant differences at the 95% confidence level).

After emergence of vegetation, we continue in mechanical cultivation, which consists of ploughing (eventually the use of weeder) and careful harrowing. Freshly emerged stalk is sensitive on damage, so we should practise harrowing only exceptionally. When the stalk is green and firm, harrowing is possible without great damage in the afternoon hours (when the stalks are withered). In that case, it is beneficial to use tine harrow. It damages stalks lesser than the chain harrow.

According to the need, ploughing (eventually harrowing) is repeated approximately 3 to 4 times until the full canopy closure [8]. The last cultivation intervention should be made until the formation of flower buds when they pile up the ridges as a precaution for transition of late blight from stalk to tubers.

In case the plant height reaches approximately 20 cm, it is suitable to apply (on the leaf or partially also on the soil) supportive preparations (Albit, Alga 600, Alginure, Amalgerol Premium, Ferbiflor, Lignohumate B, PRP-EBV and others).

### **8. Regulation of pests and diseases**

Potatoes can have many diseases (i.e. viral, bacterial, or fungal). For the major part, it is possible to only apply preventive procedures. Direct intervention is possible only in case of fungal diseases.

Potato pests attack mainly stalks and tubers. Some of them are also transferring agents of diseases (for example, aphides transfer plant viruses).

### **8.1. Late blight (Phythophora infestans)**

Late blight is a serious disease on the worldwide scale. If the conditions are favorable, it spreads quickly, and after three weeks, it is able to totally defoliate vegetation [16]. Its regulation in conditions of organic farming is very difficult. The grower must maximally use available preventive methods of pathogen regulation. The assumption is to use known pathogen biology including his weakness.

Varieties of potatoes show marked differences in susceptibility to the late blight. The choice of variety is deciding, because the possibilities of direct crop protection are limited in organic farming. Abroad are already known resistant varieties (Defender, Jacqueline Lee) or varieties with high resistance against it (Sapro Mira, Bionta).

Early term of planting and biological preparation of planting material reduce mainly the risk of yield loss because the later the epidemic shows up (in later stage of plant development), the bigger the tubers are and the lower the losses of yield.

For regulation of late blight, it is possible to use methods that decrease the time of moistening. In case of irrigation need, it is preferable to use the drop irrigation than the spray irrigation (it also saves water). Time-controlled irrigation can markedly decrease the time of moistening. The best time of irrigation is early in the morning, during dew [17]. Unambiguously, it is not suitable to irrigate in late afternoon hours when the stalks cannot dry up before sun-down and usually stay moistall night, which leads to wetting for a very long time and to higher risk of diseases.

The recommended methods of regulation of late blight are suitable organization of vegetation (spacing and row orientation). Orientation of rows is recommended for dominant air circula‐ tion. Wide rows (80 to 90 cm) can enhance air circulation and wider rows (90 to 120 cm) prevent canopy closure, which assure longer time of air circulation and makes vegetation dry faster after precipitation. But after, there is lower soil shading and higher concurrence of weeds. Weed occurrence in potato vegetation decreases air circulation and increases the infection risk. In addition, those weeds can be hosts to late blight (*Solanaceae*).

It is also possible to introduce some plants in the vegetation that can reduce the risk of late blight. These new plants form a barrier against the spreading of spores. Some studies mention positive effects of intercropping potatoes with wheat. Potatoes are planted diagonally to dominate air circulation and wheat is sowed in the furrows. Another alternative method verified in the project Blight-MOP with positive result was alternate (band) cultivation of varieties resistible and sensitive to the late blight on one site or cultivation of more varieties in one row. This mixture of varieties can improve control over pathogen, but induce practical problems with harvest and variety separation [18].

Balanced plant nutrition including microelements decreases the possibility of late blight infection of potatoes [1]. Overdose of nitrogen fertilizer forms less tubers and lots of stalks that dry up slower, which increases the infection risk. More resistant are mature "older" stalks [16] well-supplied with potassium [1].

Potato pests attack mainly stalks and tubers. Some of them are also transferring agents of

Late blight is a serious disease on the worldwide scale. If the conditions are favorable, it spreads quickly, and after three weeks, it is able to totally defoliate vegetation [16]. Its regulation in conditions of organic farming is very difficult. The grower must maximally use available preventive methods of pathogen regulation. The assumption is to use known pathogen biology

Varieties of potatoes show marked differences in susceptibility to the late blight. The choice of variety is deciding, because the possibilities of direct crop protection are limited in organic farming. Abroad are already known resistant varieties (Defender, Jacqueline Lee) or varieties

Early term of planting and biological preparation of planting material reduce mainly the risk of yield loss because the later the epidemic shows up (in later stage of plant development), the

For regulation of late blight, it is possible to use methods that decrease the time of moistening. In case of irrigation need, it is preferable to use the drop irrigation than the spray irrigation (it also saves water). Time-controlled irrigation can markedly decrease the time of moistening. The best time of irrigation is early in the morning, during dew [17]. Unambiguously, it is not suitable to irrigate in late afternoon hours when the stalks cannot dry up before sun-down and usually stay moistall night, which leads to wetting for a very long time and to higher risk of

The recommended methods of regulation of late blight are suitable organization of vegetation (spacing and row orientation). Orientation of rows is recommended for dominant air circula‐ tion. Wide rows (80 to 90 cm) can enhance air circulation and wider rows (90 to 120 cm) prevent canopy closure, which assure longer time of air circulation and makes vegetation dry faster after precipitation. But after, there is lower soil shading and higher concurrence of weeds. Weed occurrence in potato vegetation decreases air circulation and increases the infection risk.

It is also possible to introduce some plants in the vegetation that can reduce the risk of late blight. These new plants form a barrier against the spreading of spores. Some studies mention positive effects of intercropping potatoes with wheat. Potatoes are planted diagonally to dominate air circulation and wheat is sowed in the furrows. Another alternative method verified in the project Blight-MOP with positive result was alternate (band) cultivation of varieties resistible and sensitive to the late blight on one site or cultivation of more varieties in one row. This mixture of varieties can improve control over pathogen, but induce practical

Balanced plant nutrition including microelements decreases the possibility of late blight infection of potatoes [1]. Overdose of nitrogen fertilizer forms less tubers and lots of stalks that

diseases (for example, aphides transfer plant viruses).

with high resistance against it (Sapro Mira, Bionta).

bigger the tubers are and the lower the losses of yield.

In addition, those weeds can be hosts to late blight (*Solanaceae*).

problems with harvest and variety separation [18].

**8.1. Late blight (Phythophora infestans)**

160 Organic Farming - A Promising Way of Food Production

including his weakness.

diseases.

In case of occurrence of late blight in the vegetation (when preventive methods did not work), it is possible to alternatively approach the destruction of the first infected plants on site. It can stop or slow down the spreading of the disease to the rest of the site. We have to eliminate not only the visibly ill plants, but also the plants around the focus point because they may be infected though without any symptoms. The appearance of symptoms takes around three days to one week (depending on environmental conditions). Results of these methods are the elimination of many apparently healthy plants, which are enclosed by the infected plants. For these purposes, it is possible to use, for example, a propane-butane burner, which can ensure the destruction of spores.

Opinions on the use of preparations on the basis that copper is markedly different (grower to grower, state to state) is mainly dependent on legislation. In some states, copper fungicide was limited. According to the EU, they determined a boundary of 6 kg of Cu/ha/year. In Scandi‐ navia, copper fungicides cannot be used at all. Growers there are trying to use alternative products, but with smaller success. In present conditions, the ban of copper fungicide could destabilize the production of organic potatoes because there are no other effective alternatives for blight regulation.

In our experiments from 2009 to 2011, solutions of plant and animal origin were tested and supplemented with five hopeful commercial preparations (Figure 14). First, preventive spraying was always done before occurrence of blight, and consequent treatment was done according to prognostics and signalization. The site, where the experiment occurred, was typical for lower blight attack on stalks and tubers, so even the use of alternative spraying had satisfactory results compared with copper fungicide. We also observed mild phytotoxicity of preparation with the extract from walnut tree (*Juglans regia* L.), which probably had an effect on tuber yield.


**Table 2.** Incidence of Late Blight on the leaves and tubers of potato (expressed in % of infected leaves and infected tubers)

Another comparison of commercial preparations is represented in Figure 14. Surprisingly, the best results on blight regulation were observed with preparations against Colorado potato beetle (Neem Azal T/S and safety net). It affirmed the recent finding that regulation of CPB in organic farming (regulation of leaf damage) has a positive effect on the decrease of blight in potato vegetation.

**Figure 14.** Results of applications support preparations in average varieties (Monika, Jelly, and Red Anna) on station Uhříněves (2009–2011).

### **8.2. Colorado potato beetle (Leptinotarsa decemlineata)**

CPB is a pest of potatoes, which after overpopulation induce serious damage of vegetation and decrease of tuber yield [1]. The biggest damage is caused by its larvae. Their overpopulation can lead to clean-eating, leading to the destruction of vegetation. This pest should not be undermined.

From preventive precaution, it is possible to recommend pre-sprouting and early planting, not place the potatoes on near-by sites (easily admissible for beetles), aim for support of natural enemies (lady-bugs, heteroptera, earwig, and birds such as blackbird, pheasant, or partridge), and application of mulch. From variety experiments are some possible different attacks (attractiveness of varieties for Colorado beetle). The deciding factor can be the content of glycoalcaloids or trichomes on leaves.

Direct crop protection on large area consists of applications of biological insecticide. Currently registered in the Czech Republic are two effective substances: azadirachtin (in Neem Azal T/S) and spinosad (in Spintor). In some states, it is possible to use biological preparation Novodor FC on the basis of bacteria *Bacillus thuringiensis* var. *tenebrionis.*

On smaller areas, it is possible to use labor-intensive way of hand collecting (mainly of spring beetles), which aims to prevent the laying of eggs. Uniquely, it is possible to find special shakers or blowers (eventually vacuums), but they are usually homemade machines or prototypes.

### **9. Preparation of harvest and harvest methods**

Removing stalks happens usually early in organic farming because of late blight (with the removal of stalks, we follow the regulation of inoculum and spread of infection on tubers). In case of very early potatoes, we remove stalks mainly for simplification of harvest and hard‐ ening of the peel (in this case 2 to 3 weeks before planed harvest). To remove the stalks, we use a mechanical stalk crusher in organic farming.

In case of production of planting material, stalk removal is necessary and unavoidable mainly from the point of view of viral regulation (eventually the pass of aphids). A more efficient procedure (mainly with planting material) is thermic removal of stalks (fire, vapor, or nitrogen).

On certain conditions it is possible to use even the tweezers of stalks (only with erect vegetation on consistent soil so it would not tear out the tubers). These machines are not available in the Czech Republic, so there are not even used [19].

### **10. Conclusion**

**Figure 14.** Results of applications support preparations in average varieties (Monika, Jelly, and Red Anna) on station

CPB is a pest of potatoes, which after overpopulation induce serious damage of vegetation and decrease of tuber yield [1]. The biggest damage is caused by its larvae. Their overpopulation can lead to clean-eating, leading to the destruction of vegetation. This pest should not be

From preventive precaution, it is possible to recommend pre-sprouting and early planting, not place the potatoes on near-by sites (easily admissible for beetles), aim for support of natural enemies (lady-bugs, heteroptera, earwig, and birds such as blackbird, pheasant, or partridge), and application of mulch. From variety experiments are some possible different attacks (attractiveness of varieties for Colorado beetle). The deciding factor can be the content of

Direct crop protection on large area consists of applications of biological insecticide. Currently registered in the Czech Republic are two effective substances: azadirachtin (in Neem Azal T/S) and spinosad (in Spintor). In some states, it is possible to use biological preparation

On smaller areas, it is possible to use labor-intensive way of hand collecting (mainly of spring beetles), which aims to prevent the laying of eggs. Uniquely, it is possible to find special shakers or blowers (eventually vacuums), but they are usually homemade machines or prototypes.

Removing stalks happens usually early in organic farming because of late blight (with the removal of stalks, we follow the regulation of inoculum and spread of infection on tubers). In

Novodor FC on the basis of bacteria *Bacillus thuringiensis* var. *tenebrionis.*

**9. Preparation of harvest and harvest methods**

**8.2. Colorado potato beetle (Leptinotarsa decemlineata)**

glycoalcaloids or trichomes on leaves.

162 Organic Farming - A Promising Way of Food Production

Uhříněves (2009–2011).

undermined.

Existing knowledge and experiences in the technology of cultivation of organic potatoes are continuously innovated and specific issues of growers are addressed. Especially valuable are the findings in the field of soil treatment and processing as they affect the soil state and the soil edaphon, which has an irreplaceable role in the system of ecological agriculture. Adequate soil treatment and application of organic materials, combined with biological preparations, have positive impact on the nutritional state of vegetation and are effective ways of how to balance nutrients in organic farming. In our experiments, the nutritional state of vegetation and the tuber yield improved by using soil preparations of Azoter (yield increased by 1.1 t/ha) and AlgaSoil (increase by 0.9 t/ha). The growers solved the nutrient deficit found during vegetation only marginally. Even here, the supply is growing and the organic grower already can apply liquid or organomineral fertilizers with quick nitrogen effect on the basis of actual nutritive state of plants. Another big group of preparation is the so-called supplemental plant preparations. We had the chance to verify some preparations of this group (Albit, Alga 600, Amalgerol, Lignohumate B, PRP-EBV, or Softguard) with positive results. Another benefit of these preparations is their possible effect on the health of plants.

The health, even the tuber yield, of potatoes is possible to influence with some other operation such as the choice of variety, size sorting of planting material, and treatment of plant material. The use of greater size sorting and of tubers of overplanting size increased the tuber yield in combination with early harvest. It is necessary in organic farming to perform biological preparation of planting material (pre-sprouting) because of late blight. Consequential growth of roots and vegetation vitality is possible to support with treatment of planting material before planting or application during planting (on potato planter).

The protection of soil and soil life is also important. The application of mulching material on top of ridges can help in this area (also as anti-erosion precaution). Another benefit of mulch is that it can be used in the regulation of CPB or aphids (mainly if we use herbal mulch or buffer strip), weed regulation (weed biomass was regulated by black mulching fabric and partially by grass mulch applied before emergence), the possibility of temperature and humidity regulation, and also the increase of tuber yield. The tuber yield was largely affected by concrete use of mulching material (the right choice of mulching material unrolls from concrete site and soil conditions).

Initial treatment of potato vegetation happens according to concrete environmental conditions of the year and the grower's experiences. We gain many valuable results about plant extracts of *Azadirachta indica* L., eventually Neem Azal and other plant extracts (*Juglans regia* L., *Pelargonium zonale* L.) as protection against late blight and CPB. However, they are not usable in practise because of their changing effectivity. The main regulation procedure includes: 1. choice and use of resistant varieties; 2. pre-sprouting of planting material and early planting; 3. suitable irrigation regime; 4. interchange of crops; 5. removal of stalks or use of copper fungicide.

Aimed liquidation of stalks stops not only the blight spread, but also its transition to the soil and on tubers. Another area using stalk removal is the regulation of maturation (tuber size) and regulation of viruses (in propagation vegetation). Experimental results indicate, that even after stronger pass of aphids, it is possible to use preventive methods (early varieties, presprouting, early planting, buffer strip, or mulching) in organic farming and regulate the occurrence of viral diseases. Production of planting material is possible even in conditions of organic farming. It demands good knowledge and maximal usage of all regulation methods and procedures.

### **Acknowledgements**

This publication are from results gained from solving the projects MSM6046070901, MSN 590 G4, CIGA 20062005, MZe ČR č. QH82149.

### **Author details**

Petr Dvořák\* , Jaroslav Tomášek, Karel Hamouz and Michaela Jedličková

\*Address all correspondence to: dvorakp@af.czu.cz

Czech University of Life Sciences Prague, Faculty of Agrobiology, Food and Natural Resources, Kamýcká, Prague – Suchdol, Czech Republic

### **References**

[1] Vokál B. 2004. Technologie pěstování brambor: (rozhodovací systémy pro optimali‐ zaci pěstitelských technologií u jednotlivých užitkových směrů brambor). Praha: Ús‐ tav zemědělských a potravinářských informací, 91s. ISBN 80-727-1155-5.


by concrete use of mulching material (the right choice of mulching material unrolls from

Initial treatment of potato vegetation happens according to concrete environmental conditions of the year and the grower's experiences. We gain many valuable results about plant extracts of *Azadirachta indica* L., eventually Neem Azal and other plant extracts (*Juglans regia* L., *Pelargonium zonale* L.) as protection against late blight and CPB. However, they are not usable in practise because of their changing effectivity. The main regulation procedure includes: 1. choice and use of resistant varieties; 2. pre-sprouting of planting material and early planting; 3. suitable irrigation regime; 4. interchange of crops; 5. removal of stalks or use of copper

Aimed liquidation of stalks stops not only the blight spread, but also its transition to the soil and on tubers. Another area using stalk removal is the regulation of maturation (tuber size) and regulation of viruses (in propagation vegetation). Experimental results indicate, that even after stronger pass of aphids, it is possible to use preventive methods (early varieties, presprouting, early planting, buffer strip, or mulching) in organic farming and regulate the occurrence of viral diseases. Production of planting material is possible even in conditions of organic farming. It demands good knowledge and maximal usage of all regulation methods

This publication are from results gained from solving the projects MSM6046070901, MSN 590

, Jaroslav Tomášek, Karel Hamouz and Michaela Jedličková

Czech University of Life Sciences Prague, Faculty of Agrobiology, Food and Natural

[1] Vokál B. 2004. Technologie pěstování brambor: (rozhodovací systémy pro optimali‐ zaci pěstitelských technologií u jednotlivých užitkových směrů brambor). Praha: Ús‐

tav zemědělských a potravinářských informací, 91s. ISBN 80-727-1155-5.

concrete site and soil conditions).

164 Organic Farming - A Promising Way of Food Production

fungicide.

and procedures.

**Author details**

Petr Dvořák\*

**References**

**Acknowledgements**

G4, CIGA 20062005, MZe ČR č. QH82149.

\*Address all correspondence to: dvorakp@af.czu.cz

Resources, Kamýcká, Prague – Suchdol, Czech Republic


### **Organic Tuber Production is Promising — Implications of a Decade of Research in India**

Suja Girija, Sreekumar Janardanan, Jyothi Alummoottil Narayanan and Santosh Mithra Velayudhan Santhakumari

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/61846

### **Abstract**

[17] Kirk W., Wharton P., Hammerschmidt R., Abu-El Samen F., Douches D. 2007. Late Blight [Online]. Michigan State University Extension Bulletin E-2945. East Lansing,

[18] Leifert C., Wilcockson S.J. 2005. Blight-MOP: Development of a systems approach for the management of late blight (caused by Phytophthora infestans) in EU organic po‐

[19] Bioinstitut, 2007. Praktická příručka č. 4 Biobrambory - Jak ekologicky vypěstovat

MI. http://www.potatodiseases.org/lateblight.html (downloaded 18.9 2014).

tato production. University of Newcastle, UK.

166 Organic Farming - A Promising Way of Food Production

kvalitní brambory. Bioinstitut, Olomouc: 23s.

Alternative soil management practices like organic farming assume significance in the context of climate change for safe food production. Yams (white yam, greater yam and lesser yam) and edible aroids (elephant foot yam (EFY), taro and tannia) are tuberous vegetables with good taste and nutritive value. Six field experiments were conducted at the ICAR-Central Tuber Crops Research Institute, Thiruvananthapuram, India, over a decade (2004–2015) to compare the varietal response, yield, quality and soil properties under organic vs conventional system and develop a learning system. The elite and local varieties of EFY and taro and the three species of yams, including trailing and dwarf gen‐ otypes, responded equally well to both the systems. Organic management enhanced the yield by 10–20% and the net profit by 20–40% over chemical farming. The tuber quality was improved with higher dry matter, starch, crude protein, K, Ca and Mg contents. The anti-nutritional factor in EFY, oxalate content, was lowered by 21%. Physico-chemical and biological properties of soil were favoured and the organic system scored a signifi‐ cantly higher soil quality index. The cost-effective technologies were field validated. A learning system developed using artificial neural networks predicted the performance of EFY organic production system.

**Keywords:** Eco-friendly farming, root crops, yield, quality, soil health, learning system

### **1. Introduction**

Worldwide concerns regarding food safety, environmental degradation and threats to human health have aroused interest in alternative sustainable agricultural systems [1]. "Land degra‐ dation" is considered to be one of the world's greatest environmental challenges as per the UN millennium ecosystem assessment. Globally, 40% of the arable land is seriously degraded and

© 2016 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 reproduction in any medium, provided the original work is properly cited.

11% of this is situated in Asia [2, 3]. The land quality for food production ensures future peace. "Organic farming" is a viable option that enables sustainable production, maintenance of soil health, protection of human health and conservation of environment. It envisages non-use of synthetic chemicals, reduced use of purchased inputs and maximum use of on-farm-generated resources [3].

High input conventional agriculture that uses large quantities of chemical inputs and few C additions silently results in irrevocable ecological and environmental calamities [4, 5]. The necessity for environmental conservation along with the desire for safe foods has made organic farming one of the fastest growing agricultural enterprises [6]. It is well documented that there is a great demand for organic produce because of the belief that organic foods are more nutritious than conventionally grown ones [3, 7]. However, the nutritional or qualitative superiority of the organic food has yet to be proved conclusively. Reduced energy use and CO2 emissions, employment generation, waste recycling and export promotion are the other merits of organic farming [3, 8, 9].

Tropical tuber crops constitute important staple or subsidiary food for about 500 million of the global population. Yams (*Dioscorea* spp.) and aroids are ethnic tuberous vegetables with good taste and medicinal values. They have high content of carbohydrate and are rich in energy. They also have higher protein content and better balance of amino acids than many other root and tuber crops. They are food security crops grown in tropical countries, mainly West Africa, the Caribbean, Pacific Islands and Southeast Asia. Tropical tuber crops in general and edible aroids like EFY, taro and tannia respond well to organic manures. Hence, there is great scope for organic production in these crops [3, 10–14]. There is a great demand for organically produced tuberous vegetables among affluent Asians and Africans living in Europe, USA and Middle East. Research and development on organic farming of tropical tuber crops is less focussed and documented. There is not much documented scientific evidence or information about the effects of organic management on yield, nutritional quality and soil health [3].

### **2. Why organic agriculture?**

The major challenge faced by world agriculture is the production of food for a population of nine billion by 2050, with the anticipated climate change [15, 16]. There is an urgent call for transformations to increase the productive capacity and stability of smallholder agricultural production systems [15]. There is considerable discussion about the inadequacy of the present system of agricultural intensification and growth, which relies on increased use of capital inputs, such as fertilizers and pesticides [15, 17]. The generation of unacceptable levels of environmental damage and problems of economic feasibility are cited as key problems [17, 18]. Increasing concerns about the negative impacts of industrial agriculture have led to a serious debate over the feasibility of transition to alternative forms of agriculture, which are capable of providing a broad suite of ecosystem services while producing stable yields for human use [15}. Greater attention is thus being given to alternative models of intensification, and in particular, the potential of sustainable land management technologies. Such practices can provide private benefits for farmers, by improving soil fertility and structure, conserving soil and water, enhancing the activity and diversity of soil fauna, and strengthening the mechanisms of nutrient cycling [15]. These benefits can lead to increased productivity and stability of agricultural production systems [19–23] and offer a potentially important means of enhancing agricultural returns and food security as well as reducing the vulnerability of farming systems to climatic risk. Organic agriculture is one such promising alternative.

### **3. Organic farming feasible in selected areas and crops in India**

11% of this is situated in Asia [2, 3]. The land quality for food production ensures future peace. "Organic farming" is a viable option that enables sustainable production, maintenance of soil health, protection of human health and conservation of environment. It envisages non-use of synthetic chemicals, reduced use of purchased inputs and maximum use of on-farm-generated

High input conventional agriculture that uses large quantities of chemical inputs and few C additions silently results in irrevocable ecological and environmental calamities [4, 5]. The necessity for environmental conservation along with the desire for safe foods has made organic farming one of the fastest growing agricultural enterprises [6]. It is well documented that there is a great demand for organic produce because of the belief that organic foods are more nutritious than conventionally grown ones [3, 7]. However, the nutritional or qualitative superiority of the organic food has yet to be proved conclusively. Reduced energy use and CO2 emissions, employment generation, waste recycling and export promotion are the other

Tropical tuber crops constitute important staple or subsidiary food for about 500 million of the global population. Yams (*Dioscorea* spp.) and aroids are ethnic tuberous vegetables with good taste and medicinal values. They have high content of carbohydrate and are rich in energy. They also have higher protein content and better balance of amino acids than many other root and tuber crops. They are food security crops grown in tropical countries, mainly West Africa, the Caribbean, Pacific Islands and Southeast Asia. Tropical tuber crops in general and edible aroids like EFY, taro and tannia respond well to organic manures. Hence, there is great scope for organic production in these crops [3, 10–14]. There is a great demand for organically produced tuberous vegetables among affluent Asians and Africans living in Europe, USA and Middle East. Research and development on organic farming of tropical tuber crops is less focussed and documented. There is not much documented scientific evidence or information about the effects of organic management on yield, nutritional quality and soil health [3].

The major challenge faced by world agriculture is the production of food for a population of nine billion by 2050, with the anticipated climate change [15, 16]. There is an urgent call for transformations to increase the productive capacity and stability of smallholder agricultural production systems [15]. There is considerable discussion about the inadequacy of the present system of agricultural intensification and growth, which relies on increased use of capital inputs, such as fertilizers and pesticides [15, 17]. The generation of unacceptable levels of environmental damage and problems of economic feasibility are cited as key problems [17, 18]. Increasing concerns about the negative impacts of industrial agriculture have led to a serious debate over the feasibility of transition to alternative forms of agriculture, which are capable of providing a broad suite of ecosystem services while producing stable yields for human use [15}. Greater attention is thus being given to alternative models of intensification, and in particular, the potential of sustainable land management technologies. Such practices

resources [3].

merits of organic farming [3, 8, 9].

168 Organic Farming - A Promising Way of Food Production

**2. Why organic agriculture?**

In India, approximately 62% of cropped area is rain-fed, where there is little or no use of fertilizers and other agro-chemicals due to poor resources with smallholder farmers. Thus, promotion of organic farming in India is advocated initially in these rain-fed areas particularly in the hilly regions of northern and northeastern parts and dry land areas of the country. The Fertilizer Association of India has identified totally about 50 districts in the states of Orissa, Jharkhand, Uttranchal, Himachal Pradesh, Jammu and Kashmir, Rajasthan, Gujarat, Madhya Pradesh and Chhattisgarh as low-fertilizer-consuming dis‐ tricts with the consumption ranging from 1.79 kg ha−1 to 19.80 kg ha−1 as against the national average of 90.2 kg ha−1 [24, 25]. This means that there is immense scope for organic farming in these selected areas and for selected crops in India, like pulses, oilseeds, tuber crops, etc., for which conventionally little or no fertilizers and agro-chemicals are used. On the other hand, some areas growing tea, coffee, cashew, nuts and spices may be easily brought under organic farming with a thrust on export of organic produce. In other words, rather than promoting organic farming *en masse*, it would be appropriate to carefully delineate areas or crops, where fertilizer use is nil or nominal, or demarcate export-oriented crops that can give a reasonable yield of high-quality produce without using chemicals. It is noteworthy that tuber crops hold great promise in this regard [24].

### **4. Tuber crops: Underground crops with hidden treasures**

Tropical tuber crops, including cassava, yams (greater yam, white yam and lesser yam), sweet potato and aroids (EFY, taro and tannia), form the most important staple or subsidiary food for about 500 million global population [24]. Tuber crops are the third most important food crops for humans after cereals and grain legumes. These crops possess high photosynthetic ability, have the capacity to yield under poor and marginal soil conditions and can tolerate adverse weather conditions. They are also recognized as the most efficient in converting solar energy, cassava producing 250 × 103 kcal ha−1 and sweet potato 240 × 103 kcal ha−1, when compared with 176 × 103 kcal ha−1 for rice, 110 × 103 kcal ha−1 for wheat and 200 × 103 kcal ha−1 for maize; hence, the tropical root crops are known to be a cheap source of energy supply. They can serve as a substitute for cereals due to higher contents of carbohydrates and calories. The higher biological efficiency and the highest rate of dry matter production per unit area per unit time make tuber crops inevitable components of our food security systems. Besides, they have the potential to serve as sources of alcohol, starch, sago, liquid glucose, vitamin C and raw materials for many other industrial products and animal feed. At times of famine, tuber crops have come in handy to overcome catastrophes and provide relief from hunger [24].

Tuber crops are cultivated in India mainly as rain-fed crops in the southern, eastern and northeastern states. These crops are the source of livelihood to small and marginal farmers and tribal population in these areas. Cassava production is mainly reported in the states of Kerala, Tamil Nadu, Andhra Pradesh and NEH regions. Sweet potato is cultivated mainly in the states of Orissa, Bihar, Jharkhand, eastern Uttar Pradesh, West Bengal, Madhya Pradesh, Mahara‐ shtra and Karnataka. Other tuber crops like yams (greater yam, white yam and lesser yam) and aroids (EFY, taro and tannia), popular as vegetables, are not yet commercially cultivated, being confined only to the home gardens in almost all the states (except EFY, which is cultivated on a commercial scale in Andhra Pradesh) [24].

### **5. Prospects of organic farming in tropical tuber crops**

Organic farming is a viable strategy targeting on sustainable production and soil, environ‐ mental and human health hand in hand. Conventional agriculture using chemical inputs results in higher yield, but it is ecologically unfriendly as it has negative impacts on food, soil, water and environmental quality. Indiscriminate use of chemical fertilizers for decades has lowered the organic carbon status of our soils to <1%. Moreover, pesticide residues cause concern over the safety of food. In traditional agriculture, though the use of chemicals (fertilizers and pesticides) is not in practice, adequate care is not often taken for the mainte‐ nance of soil health and fertility [24].

Most of the tuber crops are grown by small and marginal farmers in rain-fed areas and tribal pockets and hence the use of chemical fertilizers and insecticides is limited except in the case of cassava in the industrial production areas of Tamil Nadu (Salem, Dharmapuri, Namakkal, and South Arcot districts) and Andhra Pradesh (Rajahmundry district). Tuber crops in general and aroids in particular, like EFY, do respond well to organic manures and there is considerable scope for organic production in these crops. Further, the tropical tuber crops are well adapted to low-input agriculture. They are less prone to pest and disease infestations. Research work done in India and elsewhere had shown that the use of chemical fertilizers are beneficial in maximizing production of these groups of crops. A perusal of data in Table 1 indicates the organic production potential of tropical tubers and experimental evidences clearly indicate that productivity can be achieved satisfactorily even in the absence of chemical fertilizers through proper supplementation of nutrients using organic sources. Moreover, at present, there is a great demand for organically produced vegetables, particularly aroids and yams, among affluent Asians and Africans living in developed nations (Europe, USA and Middle East). The export of these tuberous vegetables will gain impetus through special government programmes like the Agri Export Zone (AEZ) Programme in Kerala [24].


**Table 1.** Organic production potential of tropical tuber crops

the potential to serve as sources of alcohol, starch, sago, liquid glucose, vitamin C and raw materials for many other industrial products and animal feed. At times of famine, tuber crops

Tuber crops are cultivated in India mainly as rain-fed crops in the southern, eastern and northeastern states. These crops are the source of livelihood to small and marginal farmers and tribal population in these areas. Cassava production is mainly reported in the states of Kerala, Tamil Nadu, Andhra Pradesh and NEH regions. Sweet potato is cultivated mainly in the states of Orissa, Bihar, Jharkhand, eastern Uttar Pradesh, West Bengal, Madhya Pradesh, Mahara‐ shtra and Karnataka. Other tuber crops like yams (greater yam, white yam and lesser yam) and aroids (EFY, taro and tannia), popular as vegetables, are not yet commercially cultivated, being confined only to the home gardens in almost all the states (except EFY, which is cultivated

Organic farming is a viable strategy targeting on sustainable production and soil, environ‐ mental and human health hand in hand. Conventional agriculture using chemical inputs results in higher yield, but it is ecologically unfriendly as it has negative impacts on food, soil, water and environmental quality. Indiscriminate use of chemical fertilizers for decades has lowered the organic carbon status of our soils to <1%. Moreover, pesticide residues cause concern over the safety of food. In traditional agriculture, though the use of chemicals (fertilizers and pesticides) is not in practice, adequate care is not often taken for the mainte‐

Most of the tuber crops are grown by small and marginal farmers in rain-fed areas and tribal pockets and hence the use of chemical fertilizers and insecticides is limited except in the case of cassava in the industrial production areas of Tamil Nadu (Salem, Dharmapuri, Namakkal, and South Arcot districts) and Andhra Pradesh (Rajahmundry district). Tuber crops in general and aroids in particular, like EFY, do respond well to organic manures and there is considerable scope for organic production in these crops. Further, the tropical tuber crops are well adapted to low-input agriculture. They are less prone to pest and disease infestations. Research work done in India and elsewhere had shown that the use of chemical fertilizers are beneficial in maximizing production of these groups of crops. A perusal of data in Table 1 indicates the organic production potential of tropical tubers and experimental evidences clearly indicate that productivity can be achieved satisfactorily even in the absence of chemical fertilizers through proper supplementation of nutrients using organic sources. Moreover, at present, there is a great demand for organically produced vegetables, particularly aroids and yams, among affluent Asians and Africans living in developed nations (Europe, USA and Middle East). The export of these tuberous vegetables will gain impetus through special government

have come in handy to overcome catastrophes and provide relief from hunger [24].

on a commercial scale in Andhra Pradesh) [24].

170 Organic Farming - A Promising Way of Food Production

nance of soil health and fertility [24].

**5. Prospects of organic farming in tropical tuber crops**

programmes like the Agri Export Zone (AEZ) Programme in Kerala [24].

### **6. Issues in organic tuber production**

Practical applications and operational methodologies in organic farming, especially in tuber crops, are not available due to lack of comprehensive research in this field. Absence of package of practices recommendations for organic farming of tuber crops hinders the implementation and promotion of this sustainable alternative production system. Many methods and techni‐ ques of organic agriculture have originated from various traditional farming systems all over the world, where there is the non-use of chemical inputs. To the maximum extent possible, organic production systems rely on crop rotations, crop residues, animal manures, legumes, green manures, farm wastes, mineral-bearing rocks and aspects of biological pest control to maintain soil productivity, supply plant nutrients and control pests, diseases and weeds. Being highly responsive to organic manures and having fewer pests and disease problems when compared with cereals and vegetables, the main issue in organic production of tuber crops is the proper scientific use of a wide variety of cheaper and easily available organic sources of plant nutrients [24].

### **7. Strategies for organic tuber production**

**Building up of soil fertility of the land**: Before the establishment of an organic management system, the fertility status of the land must be improved by growing green manure crops like cowpea twice or thrice in a year and incorporation of the green leaf matter at the appropriate pre-flowering stage. This will help re-establish the balance of the eco-system and offset the yield decline, if any, during the initial period of organic conversion, as tuber crops are highly nutrient-depleting crops. Virgin land or barren land, if available, will also be highly suitable for organic farming of tubers [24].

**Use of planting materials produced by organic management:** Varieties cultivated should be adapted to the soil and climatic conditions and as far as possible resistant to pests and diseases. Local market preference should also be taken into account. The planting materials should be produced by adopting organic management practices [24].

**Meeting nutrient needs in organic tuber production:** The potential organic sources of plant nutrients for tropical tuber crops are farmyard manure (FYM), poultry manure, composts like vermicompost, coir pith compost, mushroom spent compost, saw dust compost, press mud compost, green manures, crop residues, ash, oil cakes like neem cake, etc. Table 2 indicates the average nutrient contents in these organic sources [24].

Vermicompost, produced by chemical disintegration of organic matter by earthworms, is an ideal blend of plant nutrients with the worm enzyme and probiotics to boost the crop per‐ formance. It contains higher amount of nutrients, hormones and enzymes and has stimulatory effect on plant growth. If farmers can produce vermicompost utilizing on-farm wastes, organic farming of tuber crops becomes profitable [24].

Coir pith, an organic waste obtained as a by-product during the process of separation of fibre from coconut husk in the coir industry, is normally resistant to bio-degradation due to its high content of lignin, accumulating as an environmental pollutant. Extraction of 1 kg of coconut fibre generates 2 kg of coir pith, and in India, an estimated 5,00,000 MT of coir pith is produced per annum. The Coir Board in collaboration with TNAU has developed the technology for converting coir pith into organic manure using PITHPLUS, a spawn of edible mushroom, *Pleurotus sajor caju*. Coir pith compost developed from coir waste is a good form of organic manure and a soil conditioner and can be applied to tuber crops [24].


**Table 2.** Average nutrient contents of some organic manures

The practice of green manuring for improving soil fertility and supplying a part of N require‐ ment of crops is age old. Approximately 15−20 t ha−1 of green matter can be obtained from green manure crops like cowpea when grown in systems involving tuber crops. Nitrogen contribution by green manure crops varies from 60 to 280 kg ha−1 [24].

yield decline, if any, during the initial period of organic conversion, as tuber crops are highly nutrient-depleting crops. Virgin land or barren land, if available, will also be highly suitable

**Use of planting materials produced by organic management:** Varieties cultivated should be adapted to the soil and climatic conditions and as far as possible resistant to pests and diseases. Local market preference should also be taken into account. The planting materials should be

**Meeting nutrient needs in organic tuber production:** The potential organic sources of plant nutrients for tropical tuber crops are farmyard manure (FYM), poultry manure, composts like vermicompost, coir pith compost, mushroom spent compost, saw dust compost, press mud compost, green manures, crop residues, ash, oil cakes like neem cake, etc. Table 2 indicates the

Vermicompost, produced by chemical disintegration of organic matter by earthworms, is an ideal blend of plant nutrients with the worm enzyme and probiotics to boost the crop per‐ formance. It contains higher amount of nutrients, hormones and enzymes and has stimulatory effect on plant growth. If farmers can produce vermicompost utilizing on-farm wastes, organic

Coir pith, an organic waste obtained as a by-product during the process of separation of fibre from coconut husk in the coir industry, is normally resistant to bio-degradation due to its high content of lignin, accumulating as an environmental pollutant. Extraction of 1 kg of coconut fibre generates 2 kg of coir pith, and in India, an estimated 5,00,000 MT of coir pith is produced per annum. The Coir Board in collaboration with TNAU has developed the technology for converting coir pith into organic manure using PITHPLUS, a spawn of edible mushroom, *Pleurotus sajor caju*. Coir pith compost developed from coir waste is a good form of organic

for organic farming of tubers [24].

172 Organic Farming - A Promising Way of Food Production

produced by adopting organic management practices [24].

average nutrient contents in these organic sources [24].

manure and a soil conditioner and can be applied to tuber crops [24].

**Organic manures N (%) P2O5 (%) K2O (%)** Farmyard manure 0.50 0.20 0.40 Poultry manure 1.20–1.50 1.40−1.80 0.80−0.90 Vermicompost 1.50 0.40 1.80 Coir pith compost 1.36 0.06 1.10 Press mud compost 1.30 2.20 0.50 Mushroom spent compost 1.84 0.69 1.19 Sawdust compost 1.00 0.50 0.50 Biogas slurry 1.41 0.92 0.84 Neem cake 5.00 1.00 1.50 Bone meal 3.50 21.00 − Municipal compost 1.20 0.04 0.90

farming of tuber crops becomes profitable [24].

**Table 2.** Average nutrient contents of some organic manures

Source: Reference [24]

Biofertilizers offer a cheap and easily available source of nutrients, especially N and P, besides enhancing the efficiency of native and applied nutrients in the soil. The commonly used N biofertilizer for tuber crops is the N-fixing bacterium, *Azospirillum lipoferum*, which can partially meet the N demand of the crop. Powdered neem cakes also serve as an organic N source. These organic N supplements unlike the fertilizer N do not suffer much loss in the fields and enhances the N recovery. Phosphorus-solubilizing and phosphorus-mobilizing organisms such as phosphobacterium and mycorrhizae are helpful in augmenting P availa‐ bility of the soil [24].

Besides, natural reserves of rock phosphate are permitted for use as P fertilizer. Potassium for these crops can be supplied using K-rich organic amendments such as wood ash, rice straw and composted coir pith. K mobilizers can also be used for enhancing the K availability and meeting the K requirements. Harnessing the above-mentioned easily available organic sources of plant nutrients conjointly and judiciously to meet the nutrient needs of highly nutrientexhausting crops like tropical tubers will definitely help maintain/promote productivity in organic farming in the absence of chemical inputs [24].

**Pest, disease and weed management**: When compared with cereals and vegetables, tuber crops have fewer pest and disease problems. Barring a few major ones, like cassava mosaic disease (CMD), cassava tuber rot, sweet potato weevil (SPW), *Phytophthora* leaf blight in taro, and collar rot in EFY, the others are of minor significance. In general, for the management of pests and diseases, non-chemical measures or preventive cultural techniques can be resorted to. This includes use of tolerant/resistant varieties, use of healthy and disease-free planting materials, strict field sanitation (against almost all), deep ploughing (e.g. tuber rot), roguing the field (e.g. CMD), use of pheromone traps (e.g. SPW), use of trap crops (e.g. SPW, root knot nematodes), adapted crop rotations, use of neem cake (collar rot, tuber rot), use of bio-control agents like *Trichoderma*, *Pseudomonas* (collar rot, leaf blight), etc. [24].

Normally, two hand weedings are advocated in tuber crops for efficient weed management. As most of the tuber crops (except sweet potato) take approximately 75–90 days for sufficient canopy coverage, raising a short-duration intercrop (like green manure/vegetable/grain cowpea, vegetables, groundnut, etc., in cassava, cowpea in yams and aroids) can also help to a great extent to reduce weed problem. Mulching the crop using any locally available plant materials (green leaves, dried leaves, etc.) immediately after planting (in yams and aroids) will help conserve moisture and regulate temperature, apart from weed control [24].

### **8. A decade of research on organic farming of tropical tuber crops**

The following research programmes were taken up at ICAR-Central Tuber Crops Research Institute, Sreekariyam, Thiruvananthapuram, Kerala, India, during 2004–2015:


The major objectives were:


### **8.1. Methodology**

#### *8.1.1. Study site, experimental design, treatments and test variety*

Six separate field experiments were conducted at ICAR-Central Tuber Crops Research Institute, Thiruvananthapuram, India, over a decade (2004–2015) to compare organic man‐ agement over conventional system in EFY, yams and taro in an acid Ultisol (pH: 4.3–5.0). The site experiences a typical humid tropical climate. The mean annual rainfall was 1,985 mm, maximum and minimum temperatures were 31.35°C and 24.50°C, respectively, and relative humidity was 76.65%. In general, for all the sites, prior to experimentation, the fertility status of the soil was found to be medium to high for organic C (0.75–1.03%), low for available N (159–255 kg ha−1) and high for available P (142–217 kg ha−1) and available K (337–528 kg ha−1).

The impact of conventional, traditional, organic and biofertilizer production systems was evaluated in randomized block design (RBD) in EFY (var. Peerumade local) with five replica‐ tions. Comparative response of five varieties of EFY (Gajendra, Sree Padma, Sree Athira and two locals) under organic and conventional farming was also evaluated in split plot design. The gross plot size was 4.5 m × 4.5 m (25 plants) accommodating nine net plants. All the three trailing genotypes of edible *Dioscorea* (white yam: *D. rotundata* (var. Sree Priya), greater yam: *D. alata* (var. Sree Keerthi) and lesser yam: *D. esculenta* (var. Sree Latha)) were evaluated under conventional, traditional and organic farming systems in split plot design. The gross plot size was 7.2 m × 3.6 m (32 plants of white yam and greater yam and 36 plants of lesser yam) accommodating 12 net plants of white yam and greater yam and 14 plants of lesser yam. The dwarf genotype of white yam (var. Sree Dhanya) was also evaluated under conventional, traditional, organic and integrated systems in RBD with five replications. Similarly, the response of three varieties of taro (Sree Kiran, Sree Rashmi and local) to conventional, traditional and organic farming systems was studied in split plot design. In split plot design, varieties/species were assigned to main plots and production systems to sub-plots and replicated thrice. Details of production systems are given in Table 3.

The on-station organic production technology developed for EFY was validated through onfarm trials (OFT) conducted at 10 sites covering 5 ha in Kerala under the project financed by the National Horticulture Mission. In yams and taro, the technologies were confirmed through OFT conducted at seven sites.

**•** Organic farming of EFY

**•** Organic farming of yams **•** Organic farming of taro

The major objectives were:

health and economics

**8.1. Methodology**

would be safe and of good quality

**•** Varietal response to organic farming in EFY

174 Organic Farming - A Promising Way of Food Production

**•** Validation and popularization of organic farming technology in EFY

**•** To develop appropriate technologies for organic production of EFY, yams and taro, which

**•** To assess the impact of organic farming in these crops on productivity, tuber quality, soil

Six separate field experiments were conducted at ICAR-Central Tuber Crops Research Institute, Thiruvananthapuram, India, over a decade (2004–2015) to compare organic man‐ agement over conventional system in EFY, yams and taro in an acid Ultisol (pH: 4.3–5.0). The site experiences a typical humid tropical climate. The mean annual rainfall was 1,985 mm, maximum and minimum temperatures were 31.35°C and 24.50°C, respectively, and relative humidity was 76.65%. In general, for all the sites, prior to experimentation, the fertility status of the soil was found to be medium to high for organic C (0.75–1.03%), low for available N (159–255 kg ha−1) and high for available P (142–217 kg ha−1) and available K (337–528 kg ha−1). The impact of conventional, traditional, organic and biofertilizer production systems was evaluated in randomized block design (RBD) in EFY (var. Peerumade local) with five replica‐ tions. Comparative response of five varieties of EFY (Gajendra, Sree Padma, Sree Athira and two locals) under organic and conventional farming was also evaluated in split plot design. The gross plot size was 4.5 m × 4.5 m (25 plants) accommodating nine net plants. All the three trailing genotypes of edible *Dioscorea* (white yam: *D. rotundata* (var. Sree Priya), greater yam: *D. alata* (var. Sree Keerthi) and lesser yam: *D. esculenta* (var. Sree Latha)) were evaluated under conventional, traditional and organic farming systems in split plot design. The gross plot size was 7.2 m × 3.6 m (32 plants of white yam and greater yam and 36 plants of lesser yam) accommodating 12 net plants of white yam and greater yam and 14 plants of lesser yam. The dwarf genotype of white yam (var. Sree Dhanya) was also evaluated under conventional, traditional, organic and integrated systems in RBD with five replications. Similarly, the response of three varieties of taro (Sree Kiran, Sree Rashmi and local) to conventional, traditional and organic farming systems was studied in split plot design. In split plot design, varieties/species were assigned to main plots and production systems to sub-plots and

**•** On-farm validation of organic farming of yams and taro

*8.1.1. Study site, experimental design, treatments and test variety*

replicated thrice. Details of production systems are given in Table 3.

Chemical inputs were not used for a year prior to the start of the investigations. In "conven‐ tional plots", FYM + nitrogen, phosphorus, potassium (NPK) fertilizers were applied. Farmers' practice of using FYM and ash was followed in "traditional plots". In "organic farming plots", FYM, green manure, ash, neem cake and/or biofertilizers were applied to substitute chemical fertilizers. In "biofertilizer farming", FYM, mycorrhiza, *Azospirillum* and phosphobacterium were applied. In "integrated farming", FYM, chemical fertilizers and biofertilizers were used. Organically produced planting materials were used for the study.


**Table 3.** Description of production systems in various organic farming experiments

### *8.1.2. Plant and soil measurements*

Pooled analysis of yield data was performed. Yield stability index was calculated using the following formula: stability index = (Avg Y−SD)/Ymax, where Avg Y = average yield over five years, SD = standard deviation, Ymax = maximum yield over the five years. A stability index value towards unity indicates greater stability. Proximate analyses of tubers for dry matter, starch, total sugars, reducing sugars, crude protein, oxalates and total phenols [30–33], mineral composition of corms, namely P, K, Ca, Mg, Cu, Zn, Mn and Fe contents [34], chemical parameters of soil, namely organic C (soil organic matter (SOM)), pH, available N, P, K, Ca, Mg, Cu, Zn, Mn and Fe status [35], physical characters of the soil such as bulk density, particle density, water-holding capacity (WHC) and porosity [36], plate count of soil microbes, namely bacteria, fungi, actinomycetes, N fixers and P solubilizers [37] and the activity of dehydro‐ genase enzyme [38], were determined by standard procedures. Economic analysis was performed; net income and benefit:cost ratio were computed. The soil quality index (SQI) was computed in EFY based on the method developed by Karlen and Stott [39]. The analysis of variance of data was performed using reference [40] by applying analysis of variance technique (ANOVA) for RBD and split plot design.

### *8.1.3. Development of a learning system*

A learning system was developed using artificial neural networks (ANN) to predict the performance of EFY production system [41, 42]. A three-layered system with one input layer, one output layer and one hidden layer was developed. The input layer neurons included temperature, rainfall, planting material, FYM, potassium, phosphorus, ash, neem cake, *Azospirillum*, phosphobacteria, mycorrhiza and green manure. The output layer neurons were total biomass, corm yield, canopy spread and plant height.

### **8.2. Implications**

### *8.2.1. Varietal response to organic management*

Pooled analysis indicated that the elite and local varieties of EFY and taro and all the three species of *Dioscorea* were on a par under both the systems (Figure 1). However, the Gajendra variety of EFY and all the species of *Dioscorea* yielded more under organic farming than conventional practice (Figure 1). In taro, all the varieties produced slightly higher yield under chemical farming.

### *8.2.2. Yield and economics*

Organic farming resulted in 10–20% higher yield in EFY, white yam, greater yam, lesser yam and dwarf white yam, i.e., 20, 9, 11, 7 and 9%, respectively (Table 4). This is contrary to some of the reports that crop yields under organic management are 20–40% lower than those under comparable conventional systems [43, 44]. Taro preferred chemical-based farming as a slight reduction in the crop yield was noticed under organic farming (5%).

Organic Tuber Production is Promising — Implications of a Decade of Research in India http://dx.doi.org/10.5772/61846 177

**Figure 1.** Varietal response to organic farming in tuber crops

*8.1.2. Plant and soil measurements*

176 Organic Farming - A Promising Way of Food Production

(ANOVA) for RBD and split plot design.

*8.2.1. Varietal response to organic management*

total biomass, corm yield, canopy spread and plant height.

*8.1.3. Development of a learning system*

**8.2. Implications**

chemical farming.

*8.2.2. Yield and economics*

Pooled analysis of yield data was performed. Yield stability index was calculated using the following formula: stability index = (Avg Y−SD)/Ymax, where Avg Y = average yield over five years, SD = standard deviation, Ymax = maximum yield over the five years. A stability index value towards unity indicates greater stability. Proximate analyses of tubers for dry matter, starch, total sugars, reducing sugars, crude protein, oxalates and total phenols [30–33], mineral composition of corms, namely P, K, Ca, Mg, Cu, Zn, Mn and Fe contents [34], chemical parameters of soil, namely organic C (soil organic matter (SOM)), pH, available N, P, K, Ca, Mg, Cu, Zn, Mn and Fe status [35], physical characters of the soil such as bulk density, particle density, water-holding capacity (WHC) and porosity [36], plate count of soil microbes, namely bacteria, fungi, actinomycetes, N fixers and P solubilizers [37] and the activity of dehydro‐ genase enzyme [38], were determined by standard procedures. Economic analysis was performed; net income and benefit:cost ratio were computed. The soil quality index (SQI) was computed in EFY based on the method developed by Karlen and Stott [39]. The analysis of variance of data was performed using reference [40] by applying analysis of variance technique

A learning system was developed using artificial neural networks (ANN) to predict the performance of EFY production system [41, 42]. A three-layered system with one input layer, one output layer and one hidden layer was developed. The input layer neurons included temperature, rainfall, planting material, FYM, potassium, phosphorus, ash, neem cake, *Azospirillum*, phosphobacteria, mycorrhiza and green manure. The output layer neurons were

Pooled analysis indicated that the elite and local varieties of EFY and taro and all the three species of *Dioscorea* were on a par under both the systems (Figure 1). However, the Gajendra variety of EFY and all the species of *Dioscorea* yielded more under organic farming than conventional practice (Figure 1). In taro, all the varieties produced slightly higher yield under

Organic farming resulted in 10–20% higher yield in EFY, white yam, greater yam, lesser yam and dwarf white yam, i.e., 20, 9, 11, 7 and 9%, respectively (Table 4). This is contrary to some of the reports that crop yields under organic management are 20–40% lower than those under comparable conventional systems [43, 44]. Taro preferred chemical-based farming as a slight

reduction in the crop yield was noticed under organic farming (5%).

It has been reported that yields were directly related to the intensity of farming in the prevailing conventional system [45, 46]. This means that in areas of intensive farming system, shifting to organic agriculture decreases the yield depending on the intensity of external input use before conversion [48, 49]. As EFY and yams are traditionally grown with low external inputs using organic wastes and manures available in the homesteads, organic management in the present study has shown a potential to increase yields over conventional practice. The higher yield may be due to the overall improvement in the physico-chemical and biological properties of soil under the influence of organic manures [9, 50, 51].


**Table 4.** Yield (t ha−1) under organic vs conventional management in tuber crops (pooled mean)

Tropical tuber crops, like EFY and yams, are nutrient-exhausting crops. In general, the nutrient removal by these crops yielding 17–33 tonnes of tuber was 112–180 kg N, 15–24 kg P and 93– 239 kg K per ha [52]. The potential yield of these crops can be obtained by proper renewal of soil with adequate amounts of nutrients. These results highlight that in the absence of chemical fertilizers, in organic agriculture, a higher yield can be obtained through proper addition of nutrients based on soil testing by way of cheaper and easily available, on-farm-generated organic sources [3].

The long-term performance of organic vs conventional management in aroids and yams was analysed through the stability index calculated over a five-year period, and it was found that organic farming was equally stable as that of conventional practice (Figure 2).

**Figure 2.** Yield stability index in organic vs conventional management in aroids and yams

The view of field experimentation in EFY is given in Figure 3. Yield trend over five years and pooled analysis indicated the significantly superior performance of organic farming in EFY (Figure 4; Table 5). Cost–benefit analysis in EFY indicated that the net profit was 28% higher and an additional income of Rs. 47,716 ha−1 was obtained due to organic farming, which was obviously due to 20% higher yield [12] (Table 5).

In yams, up to third year, organic farming proved to be superior; thereafter, it was on a par and slightly lower than conventional practice. Pooled analysis in yams indicated that organic farming was significantly superior to conventional practice and produced 9.12% higher yield (Figure 5; Table 6). Species × production systems interaction was absent. However, in all the species, organic farming produced slightly higher yield than conventional practice. Dwarf white yam also responded similarly to both the systems with slightly higher yield under organic practice (Figures 6 and 7).

In taro, yield trend over five years (except during the first year, when organic farming was superior to conventional practice) and pooled mean indicated that organic farming was on a par with conventional practice, but chemical farming produced a slightly higher yield (Table 4; Figures 8 and 9). This was because taro leaf blight could not be controlled by organic measures.

Tropical tuber crops, like EFY and yams, are nutrient-exhausting crops. In general, the nutrient removal by these crops yielding 17–33 tonnes of tuber was 112–180 kg N, 15–24 kg P and 93– 239 kg K per ha [52]. The potential yield of these crops can be obtained by proper renewal of soil with adequate amounts of nutrients. These results highlight that in the absence of chemical fertilizers, in organic agriculture, a higher yield can be obtained through proper addition of nutrients based on soil testing by way of cheaper and easily available, on-farm-generated

The long-term performance of organic vs conventional management in aroids and yams was analysed through the stability index calculated over a five-year period, and it was found that

organic farming was equally stable as that of conventional practice (Figure 2).

**Figure 2.** Yield stability index in organic vs conventional management in aroids and yams

obviously due to 20% higher yield [12] (Table 5).

organic practice (Figures 6 and 7).

The view of field experimentation in EFY is given in Figure 3. Yield trend over five years and pooled analysis indicated the significantly superior performance of organic farming in EFY (Figure 4; Table 5). Cost–benefit analysis in EFY indicated that the net profit was 28% higher and an additional income of Rs. 47,716 ha−1 was obtained due to organic farming, which was

In yams, up to third year, organic farming proved to be superior; thereafter, it was on a par and slightly lower than conventional practice. Pooled analysis in yams indicated that organic farming was significantly superior to conventional practice and produced 9.12% higher yield (Figure 5; Table 6). Species × production systems interaction was absent. However, in all the species, organic farming produced slightly higher yield than conventional practice. Dwarf white yam also responded similarly to both the systems with slightly higher yield under

In taro, yield trend over five years (except during the first year, when organic farming was superior to conventional practice) and pooled mean indicated that organic farming was on a

organic sources [3].

178 Organic Farming - A Promising Way of Food Production

**Figure 3.** View of field experimentation in EFY


**Table 5.** Yield and economic advantage of organic farming over other production systems in EFY

**Figure 4.** Yield trend over years as influenced by production systems in EFY

Figure 4. Yield trend over years as influenced by production systems in EFY

Field view of organic farming of yams: Green manuring, cost effective component

Organic white yam tubers Organic greater yam tubers Organic lesser yam tubers

Figure 5. Field experimentation on organic farming of trailing genotypes of yams

**Figure 5.** Field experimentation on organic farming of trailing genotypes of yams


**Table 6.** Yield response of *Dioscorea* species to production systems (t ha−1) (pooled mean) 12

Figure 7. Yield trend over years as affected by production systems in dwarf white yam

Figure 8. Field view of organic taro production with green manuring as the component

Field view of organic farming of dwarf white yam: Green manuring, cost effective component

Figure 6. Field experimentation on organic dwarf white yam production

**Figure 4.** Yield trend over years as influenced by production systems in EFY

180 Organic Farming - A Promising Way of Food Production

Figure 4. Yield trend over years as influenced by production systems in EFY

Organic white yam tubers Organic greater yam tubers Organic lesser yam tubers Figure 5. Field experimentation on organic farming of trailing genotypes of yams

**Figure 5.** Field experimentation on organic farming of trailing genotypes of yams

Field view of organic farming of yams: Green manuring, cost effective component

11

**Figure 6.** Field experimentation on organic dwarf white yam production

12

**Figure 7.** Yield trend over years as affected by production systems in dwarf white yam

Figure 7. Yield trend over years as affected by production systems in dwarf white yam

**Figure 8.** Field view of organic taro production with green manuring as the component

**Figure 9.** Yield trend as affected by production systems in taro

### *8.2.3. Nutritional quality of tubers*

12

**Figure 7.** Yield trend over years as affected by production systems in dwarf white yam

**Figure 8.** Field view of organic taro production with green manuring as the component

Figure 7. Yield trend over years as affected by production systems in dwarf white yam

Figure 6. Field experimentation on organic dwarf white yam production

182 Organic Farming - A Promising Way of Food Production

It is well known that plants absorb nutrients in the form of inorganic ions irrespective of whether the nutrient source is organic or inorganic. The absorbed nutrients are re-synthesized into compounds that determine the quality of the produce, which is largely decided by the genetic make-up of the plants [5, 12]. However, in the present research, dry matter and starch contents of organically produced EFY corms were significantly higher (by 7 and 13%), and crude protein (by 12%), K, Ca and Mg (by 3–7%) were slightly higher than those of conventional corms (Tables 7 and 8 and Figures 10 and 11). The anti-nutritional factor, oxalate, content in EFY was significantly lower (by 21%) due to organic management. Total sugar and total phenol contents of conventional corms were significantly higher. In yams, the tuber quality was improved with significantly higher Ca, slightly higher dry matter, crude protein (by 6–7%), K and Mg contents. Synthetic fertilizers enhanced the total sugars, reducing sugars and total phenol contents slightly. The cooking quality of organically produced tubers did not differ from that of conventional tubers (Tables 7 and 8 and Figures 10 and 11).

Earlier reports indicate that organic crops contain more dry matter, minerals, especially Fe, Mg and P, by 21, 29 and 14% over conventionally produced ones [7]. As stated in references [3, 53], higher levels of K were found in organic tomatoes. There is a higher population of micro-organisms in organically managed soil. These micro-organisms produce many com‐ pounds that combine with soil minerals and make them more available to plant roots [54], which might have ultimately enhanced the mineral content of tubers.

**Figure 10.** Per cent increase/decrease in biochemical parameters of organic tubers


**Table 7.** Comparison of biochemical constituents of organic vs conventional tubers


**Table 8.** Comparison of mineral content of organic vs conventional tubers

**Figure 10.** Per cent increase/decrease in biochemical parameters of organic tubers

184 Organic Farming - A Promising Way of Food Production

0.186 0.234 0.0259

**Table 7.** Comparison of biochemical constituents of organic vs conventional tubers

Dry matter (%) 21.41 19.93 1.061 33.56 31.36 NS

**EFY Yams** Organic Conventional CD (0.05) Organic Conventional CD (0.05)

16.54 14.68 0.937 26.40 26.70 NS

2.04 1.82 NS 2.04 1.92 NS

1.98 2.38 0.257 1.88 2.52 NS

0.65 0.78 NS 0.12 0.13 NS

69.70 80.80 8.28 37.20 61.60 NS

**Biochemical parameters**

Crude protein (% FW basis)

Starch (% FW basis)

Oxalate (% DW basis)

Total sugars (% FW basis)

Reducing sugar (% FW basis)

Total phenols (mg 100 g−1)

Source: Reference [14]

**Figure 11.** Per cent increase/decrease in mineral composition of organically produced tubers

Biochemical parameters of tubers were not significantly affected in taro and dwarf white yam. However, in taro, organic cormels had higher dry matter, starch and total sugars; conventional cormels had higher phenol, fibre and ash contents. Mineral content of cormels of taro also remained unaffected due to the production systems, though there was a slight increase in P, K, Ca and Mg contents in organic cormels (Figure 12).

**Figure 12.** Per cent increase/decrease in biochemical and mineral composition in organic cormels of taro

#### *8.2.4. Soil quality*

#### *8.2.4.1. Physico-chemical–biological indicators*

The water-holding capacity was significantly higher under organic management (14 g cm−3) in EFY and yams over conventional practice (11–12 g cm−3). It was 28, 15 and 19% higher than that of conventional practice in EFY, yams and taro, respectively (Tables 9 and 10). Increased aeration, porosity and water-holding capacity of soils have been observed under organic management [51, 55, 56]. Moreover, changes in organic matter contribute to changes in soil biological and physical properties [9]. The higher organic C and organic matter contents under organic management in these crops might have resulted in the formation of stable soil aggregates leading to a slight decrease in bulk density and increase in waterholding capacity [3].

There was significant improvement in pH in organic farming (0.77, 0.46, 1.11 and 1.20 unit increase over conventional system) in EFY, trailing yams, dwarf white yam and taro (Tables 11 and 12). Several earlier workers have reported that significant improvement in pH under organic management may be due to elimination of NH4 fertilizers, addition of cations espe‐ cially via green manure applications, decrease in the activity of exchangeable Al3+ ions in soil solution due to chelation by organic molecules and self-liming effect of the Ca content in FYM (0.14%) and ash (20–40%) [3, 57–59].

The organic C content increased by 14–40% in organic plots over conventional plots in these crops (Tables 11 and 12). Higher organic C status of organic plots might be attributed to considerable addition of organic manures particularly green manure cowpea. In EFY, ex‐ changeable Mg, available Cu, Mn and Fe contents were significantly higher in organic plots (Figure 13). Organic plots showed significantly higher available K (by 34%) in yams and available P in taro (Tables 11 and 12). Higher available P in organic plots may be due to solubilization of native P by organic acids during decomposition of organic manures and increased mineralization of P from the added organic manures [3, 12]. The higher content of available K in organic plots may be due to the higher content of K in the organic manures, especially green manure and ash (Table 2), greater mining of K from the sub-surface layers by the extensive root system of green manure crop of cowpea, and dissolution of K from the inaccessible K minerals in the soil by organic acids during green manure decomposition [3, 12].

The soil pH is the most important determinant of soil nutrient availability. As reported in reference [59], the rise in soil pH to neutral range under organic management in these crops might have enhanced the availability of major, secondary and micro-nutrients to some extent. Moreover, organic manures used in the study, FYM, green manure cowpea and neem cake that contain major, secondary and micro-nutrients might also have contributed to this [3, 12].

**Figure 12.** Per cent increase/decrease in biochemical and mineral composition in organic cormels of taro

The water-holding capacity was significantly higher under organic management (14 g cm−3) in EFY and yams over conventional practice (11–12 g cm−3). It was 28, 15 and 19% higher than that of conventional practice in EFY, yams and taro, respectively (Tables 9 and 10). Increased aeration, porosity and water-holding capacity of soils have been observed under organic management [51, 55, 56]. Moreover, changes in organic matter contribute to changes in soil biological and physical properties [9]. The higher organic C and organic matter contents under organic management in these crops might have resulted in the formation of stable soil aggregates leading to a slight decrease in bulk density and increase in water-

There was significant improvement in pH in organic farming (0.77, 0.46, 1.11 and 1.20 unit increase over conventional system) in EFY, trailing yams, dwarf white yam and taro (Tables 11 and 12). Several earlier workers have reported that significant improvement in pH under organic management may be due to elimination of NH4 fertilizers, addition of cations espe‐ cially via green manure applications, decrease in the activity of exchangeable Al3+ ions in soil solution due to chelation by organic molecules and self-liming effect of the Ca content in FYM

The organic C content increased by 14–40% in organic plots over conventional plots in these crops (Tables 11 and 12). Higher organic C status of organic plots might be attributed to considerable addition of organic manures particularly green manure cowpea. In EFY, ex‐ changeable Mg, available Cu, Mn and Fe contents were significantly higher in organic plots (Figure 13). Organic plots showed significantly higher available K (by 34%) in yams and

*8.2.4. Soil quality*

holding capacity [3].

(0.14%) and ash (20–40%) [3, 57–59].

*8.2.4.1. Physico-chemical–biological indicators*

186 Organic Farming - A Promising Way of Food Production


**Table 9.** Comparison of physical parameters of soil under organic vs conventional management in EFY and yams

At present, deficiency of secondary and micro-nutrients (Zn, S, B, Mo, Fe, Mn and Cu) is a rampant soil problem affecting crop productivity and profitability of farming in India [5, 12]. This is mainly due to the continuous use of high analysis fertilizers, which do not provide secondary and micro-nutrients. Based on research conducted for a decade in these crops, it has been proved beyond doubt that organic farming helps to reinstate soil productivity. Organic agriculture that envisages elimination of synthetic chemical fertilizers through strict use of organic manures helps to refurbish the soil health, by improving organic matter, neutralizing soil acidity, supplying almost all essential nutrients in the available form and ultimately conserving soil fertility [3, 5, 12].


**Table 10.** Comparison of physical parameters of soil under organic vs conventional management in taro


**Table 11.** Comparison of chemical parameters of soil under organic vs conventional management in EFY and yams

The population of bacteria was considerably higher in organic plots than in conventional plots; 41 and 23% higher in EFY and yams, respectively. Organic farming also favoured the fungal population by 17–20%. While the N fixers showed an upper hand in organically managed soils by 10% over conventional management under EFY, P solubilizers remained more conspicuous under organic management of yams (22% higher than conventional management) (Table 13). The dehydrogenase enzyme activity was higher by 23 and 14% in organic plots in EFY and yams (Table 13).

In these studies, the organic resources used to replace chemical fertilizers were FYM, green manure, neem cake and ash. Green manuring with cowpea (incorporation of 15–20 t ha−1 of green matter) was the most cost-effective component among these. The decomposition of these organic manures to release available plant nutrients involves intense microbial activity over chemical fertilizer-applied conventional plots. This might have resulted in higher microbial population and dehydrogenase enzyme activity in the organic plots. Several earlier workers also noticed increased microbial population in cultivated organically managed soil [3, 9, 60].

**Figure 13.** Per cent increase or decrease in chemical properties of soil under organic management in EFY and yams


**Table 12.** Comparison of chemical parameters of soil under organic vs conventional management in dwarf white yam and taro

#### *8.2.4.2. Development of SQI*

**Physical parameters Taro**

188 Organic Farming - A Promising Way of Food Production

Organic Conventional CD (0.05) % increase

**Chemical parameters**

Available N (kg ha−1)

Available P (kg ha−1)

Available K ( kg ha−1)

yams (Table 13).

Bulk density (g cm−3) 1.72 1.74 NS −1.38 Particle density (g cm−3) 2.63 2.63 NS +0.26 Water-holding capacity (%) 11.73 9.84 NS +19.20 Porosity (%) 34.64 33.64 NS +2.97

**Table 10.** Comparison of physical parameters of soil under organic vs conventional management in taro

**Organic Conventional CD (0.05) % increase or**

**EFY Yams**

or decrease

125.60 103.30 NS +21.59 193.00 162.00 NS +19.14

65.20 57.30 NS +13.13 270.00 289.00 NS −6.57

362.00 340.90 NS +6.19 343.50 256.40 40.21 +33.97

pH 5.32 4.55 0.285 +0.77 unit 5.47 5.01 0.212 +0.46 unit Organic C (%) 1.40 1.18 NS +19.02 0.86 0.75 NS +14.00

**Table 11.** Comparison of chemical parameters of soil under organic vs conventional management in EFY and yams

The population of bacteria was considerably higher in organic plots than in conventional plots; 41 and 23% higher in EFY and yams, respectively. Organic farming also favoured the fungal population by 17–20%. While the N fixers showed an upper hand in organically managed soils by 10% over conventional management under EFY, P solubilizers remained more conspicuous under organic management of yams (22% higher than conventional management) (Table 13). The dehydrogenase enzyme activity was higher by 23 and 14% in organic plots in EFY and

In these studies, the organic resources used to replace chemical fertilizers were FYM, green manure, neem cake and ash. Green manuring with cowpea (incorporation of 15–20 t ha−1 of green matter) was the most cost-effective component among these. The decomposition of these organic manures to release available plant nutrients involves intense microbial activity over chemical fertilizer-applied conventional plots. This might have resulted in higher microbial population and dehydrogenase enzyme activity in the organic plots. Several earlier workers also noticed increased microbial population in cultivated organically managed soil [3, 9, 60].

**decrease**

Organic Conventional CD (0.05) % increase

or decrease

In EFY, the organic system scored a significantly higher SQI (1.930), closely followed by the traditional system (1.913) (Figure 14). The SQI of conventional (1.456) and biofertilizer systems (1.580) were significantly lower. The SQI was driven by water-holding capacity, pH and available Zn followed by SOM.

**Figure 14.** Effect of production systems on SQI in EFY (Source: Reference [13])


**Table 13.** Comparison of biological parameters of soil under organic vs conventional management in EFY and yams

Soil quality is the capacity of a soil to function within natural or managed ecosystem bounda‐ ries to sustain plant and animal productivity in order to maintain or enhance water and air quality and support human health and habitation [61]. In this study, organic farming, which is a supplemental C management practice (SCMP) significantly changed a number of soil properties including soil pH, SOM, exchangeable Mg, available Cu, Mn and Fe contents and WHC. Thus, the indicator properties could be changed mainly through SOM building practices brought about by the strict use of organic manures especially green manuring continuously for five years under organic management. This framework emphasizes that soil quality assessment is a tool that can be used to evaluate the effects of land management on soil function.

### **9. On-farm validation of organic production technologies**

**Figure 14.** Effect of production systems on SQI in EFY (Source: Reference [13])

(0.05)

Organic Conventional CD

190 Organic Farming - A Promising Way of Food Production

**EFY Yams**

31 × 107 22 × 107 NS +40.90 118 × 103 96 × 103 NS +22.91

6 × 106 5 × 106 NS +20.00 7 × 102 6 × 102 NS +16.66

22 × 105 24 × 105 NS −8.33 11 × 103 12 × 103 4.682 −8.33

182 × 105 165 × 105 NS +10.30 7 × 103 11 × 103 NS −36.36

5 × 106 5 × 106 NS 0 11 × 103 9 × 103 NS +22.22

1.625 1.323 NS +22.82 1.174 0.786 NS +49.36

**Table 13.** Comparison of biological parameters of soil under organic vs conventional management in EFY and yams

Organic Conventional CD (0.05) Per cent

increase (+) or decrease (-) in organic farming

Per cent increase (+) or decrease (-) in organic farming

**Biological Parameters**

Bacteria (cfu g−1

Fungi (cfu g−1

Actinomycetes (cfu g−1 soil)

P solubilizers (cfu g−1 soil)

Dehydrogenase enzyme (μg TPF formed g−1 soil h−1)

Source: Reference [14]

soil)

soil)

N fixers (cfu g−1 soil) Demonstration trials were conducted during 2008–2009 in 10 farmers' sites to cover an area of 5 ha in Kollam and Pathanamthitta districts of Kerala to compare the yield, quality, economics and soil fertility under the organic management practices with the existing farmers' practice and conventional practice (present package of practices recommendations) in EFY (Figure 15). Organic farming resulted in higher corm yield (34.60 t ha−1) and additional income (Rs. 43,651 ha−1) over conventional farming. Organically produced corms had significantly higher dry matter and Mg contents and significantly lower oxalate content. The chemical properties of the soil, especially K, was seen to be favoured under organic farming (Table 14).


**Table 14.** Agronomic, nutritional and economic implications of organic management in EFY under validation trials

OFT were laid out in seven sites with three practices, conventional, traditional and organic, in Thiruvananthapuram and Kollam districts of Kerala to validate the on-station-developed organic farming technologies in yams (greater yam, lesser yam and dwarf white yam) and taro (Figure 15). In all sites, tuber yield under organic management was on a par with conventional practice in these crops (Figure 16). However, the yields under organic management were 8, 17, 21 and 29% higher over chemical-based farming in greater yam, lesser yam, dwarf white yam and taro, respectively. In general, there was significant improvement in pH, organic C Source: Reference [11]

sites.

trials

Yield (t ha−1) Corm dry

matter (%)

Production systems

and available K status under organic management in the sites. Soil microbial population was also improved under organic practice in these sites. were 8, 17, 21 and 29% higher over chemical‐based farming in greater yam, lesser yam, dwarf white yam and taro, respectively. In general, there was significant improvement in pH, organic C and available K status under organic management in the sites. Soil microbial population was also improved under organic practice in these

CD (0.05) 7.75 1.162 0.0076 2.045 40.02

Table 14. Agronomic, nutritional and economic implications of organic management in EFY under validation

Oxalate(DW basis %) content of corms

Conventional 24.500 19.29 0.221 91.9 98.8 70,069 1.40 Traditional 22.200 20.00 0.218 91.8 88.7 41,925 1.23 Organic 34.600 21.00 0.191 95.3 142.7 1,13,720 1.49

Mg content of corms (mg 100 g−1)

Available K of soil (kg ha−1)

yam, lesser yam and dwarf white yam) and taro (Figure 15). In all sites, tuber yield under organic management was on a par with conventional practice in these crops (Figure 16). However, the yields under organic management

Farmers convinced about green manuring Organic corms of EFY

View of OFT on yams and taro Farmers with organic tubers of greater yam

**Figure 16.** Yield under various practices in OFT in yams and taro

20

Net income (Rs ha−1)

B:C ratio

Figure 15. On‐farm validation trials conducted in Kerala

### **10. The package**

20

Net income (Rs ha−1)

B:C ratio

and available K status under organic management in the sites. Soil microbial population was

CD (0.05) 7.75 1.162 0.0076 2.045 40.02

Table 14. Agronomic, nutritional and economic implications of organic management in EFY under validation

Oxalate(DW basis %) content of corms

Conventional 24.500 19.29 0.221 91.9 98.8 70,069 1.40 Traditional 22.200 20.00 0.218 91.8 88.7 41,925 1.23 Organic 34.600 21.00 0.191 95.3 142.7 1,13,720 1.49

Mg content of corms (mg 100 g−1)

Available K of soil (kg ha−1)

OFT were laid out in seven sites with three practices, conventional, traditional and organic, in Thiruvananthapuram and Kollam districts of Kerala to validate the on‐station‐developed organic farming technologies in yams (greater yam, lesser yam and dwarf white yam) and taro (Figure 15). In all sites, tuber yield under organic management was on a par with conventional practice in these crops (Figure 16). However, the yields under organic management were 8, 17, 21 and 29% higher over chemical‐based farming in greater yam, lesser yam, dwarf white yam and taro, respectively. In general, there was significant improvement in pH, organic C and available K status under organic management in the sites. Soil microbial population was also improved under organic practice in these

also improved under organic practice in these sites.

**Figure 15.** On-farm validation trials conducted in Kerala

**Figure 16.** Yield under various practices in OFT in yams and taro

Farmers convinced about green manuring Organic corms of EFY

Yield (t ha−1) Corm dry

matter (%)

View of OFT on yams and taro Farmers with organic tubers of greater yam

Figure 15. On‐farm validation trials conducted in Kerala

trials

Production systems

Source: Reference [11]

192 Organic Farming - A Promising Way of Food Production

sites.

Use of organically produced seed materials, seed treatment in cow-dung, neem cake, bioinoculant slurry, FYM incubated with bio-inoculants, green manuring, use of neem cake, biofertilizers and ash formed the strategies for organic production (Figure 17). The organic farming package for EFY is included in the Package of Practices Recommendations for crops by Kerala Agricultural University [62].

**Figure 17.** Essential components of organic tuber production

### **11. Development of a learning system**

A learning system was developed using ANN to predict the performance of EFY production system. A three-layered system with one input layer, one output layer and one hidden layer was developed. The input layer neurons included temperature, rainfall, planting material, FYM, potassium, phosphorus, ash, neem cake, *Azospirillum*, phosphobacteria, mycorrhiza and green manure. The output layer neurons were total biomass, corm yield, canopy spread and plant height.

### **11.1. Structure of the system**

A three-layered feed-forward back-propagation network (FFBPN) (Figure 18) was designed for this learning system [41]. Its block diagram (Figure 19) explains the flow of the inputs and the modifications made on it while it passes through the different layers before the output is generated.


**Figure 18.** Learning system to predict the performance of EFY production system

Input layer of the network is composed of 12 neurons represented by I1, I2,..., I12. The activities of neurons in the input layer represent the raw information that is fed into the network. Inputs added to the neurons of the input layer are given in Table 15.

<sup>194</sup> Organic Farming - A Promising Way of Food Production 23 Organic Tuber Production is Promising — Implications of a Decade of Research in India http://dx.doi.org/10.5772/61846 195

Figure 19. Structure of the three‐layered FFBPN of the learning system **Figure 19.** Structure of the three-layered FFBPN of the learning system

**11.1. Structure of the system**

generated.

A three-layered feed-forward back-propagation network (FFBPN) (Figure 18) was designed for this learning system [41]. Its block diagram (Figure 19) explains the flow of the inputs and the modifications made on it while it passes through the different layers before the output is

**Figure 18.** Learning system to predict the performance of EFY production system

added to the neurons of the input layer are given in Table 15.

Input layer of the network is composed of 12 neurons represented by I1, I2,..., I12. The activities of neurons in the input layer represent the raw information that is fed into the network. Inputs


Input layer of the network is composed of 12 neurons represented by I1, I2,…, I12. The activities of neurons in the

5. Potassium (kg) I5 **Table 15.** List of inputs added to various neurons in the input layer of the FFBPN

4. Farmyard manure (kg) I4

6. Phosphorus (kg) I6 7. Ash (kg) I7 8. Neem cake (kg) I8 9. *Azospirillum* (kg) I9 10. Phosphobacteria (kg) I10 As linear activation function is operating in the input layer of the network, the input (I) and output (O) of the input layer are the same:

$$\left\{\mathcal{O}\right\}\_t = \left\{I\right\}\_t \tag{1}$$

The hidden neurons H1...H12 are connected by synapse to the input neurons. Let V*<sup>m</sup>*,*<sup>p</sup>* be the weight of the arc between *m*th input neuron and the *p*th hidden neuron. The input to the hidden neuron is the weighted sum of the outputs of the input neurons to get I*Hp*, i.e. the input to the *p*th hidden neuron as

$$I\_{Hp} = \sum\_{m=1, p=1}^{12, 12} V\_{m, p} \mathbf{O}\_{I, m} \tag{2}$$

where

O*I,m* is the output of *m*th input neuron.

In the hidden neurons, sigmoidal function is operating and thus the output of the *p*th hidden neuron is given by

$$O\_{llp} = \frac{1}{\left(1 + \mathcal{e}^{-\lambda(l\_{llp} - \theta\_{llp})}\right)}\tag{3}$$

where

O*Hp* is the output of the *p*th hidden neuron

I*Hp* is the input of the *p*th hidden neuron and

θ*Hp* is the threshold of the *p*th hidden neuron, which is initialized to zero in this system

Input to the output neurons is the weighted sum of the outputs of the hidden neurons. Input to the *q*th output neuron I*Oq* is calculated as follows:

$$I\_{\Omega q} = \sum\_{n=1,q=1}^{12,4} \mathcal{W}\_{n,q} \mathcal{O}\_{H,n} \tag{4}$$

where

O*Hn* is the output of the *n*th hidden neuron and

W*n,q* is the weight of the arc between *n*th hidden neuron and *q*th output neuron.

Sigmoidal function is operating in the output neurons also, and the output of the *q*th neuron is given by

Organic Tuber Production is Promising — Implications of a Decade of Research in India http://dx.doi.org/10.5772/61846 197

$$O\_{\mathcal{O}\_{\mathcal{O}}} = \frac{1}{\left(1 + e^{-\lambda(l\_{\mathcal{O}\_{\mathcal{O}}} - \theta\_{\mathcal{O}\_{\mathcal{O}}})}\right)}\tag{5}$$

where

As linear activation function is operating in the input layer of the network, the input (I) and

The hidden neurons H1...H12 are connected by synapse to the input neurons. Let V*<sup>m</sup>*,*<sup>p</sup>* be the weight of the arc between *m*th input neuron and the *p*th hidden neuron. The input to the hidden neuron is the weighted sum of the outputs of the input neurons to get I*Hp*, i.e. the input to the

, ,

In the hidden neurons, sigmoidal function is operating and thus the output of the *p*th hidden


 <sup>=</sup> <sup>+</sup> ( ) 1 (1 ) *Hp Hp*

θ*Hp* is the threshold of the *p*th hidden neuron, which is initialized to zero in this system

= = <sup>=</sup> å 12,4

W*n,q* is the weight of the arc between *n*th hidden neuron and *q*th output neuron.

1, 1 *Oq nq Hn n q*

Input to the output neurons is the weighted sum of the outputs of the hidden neurons. Input

, ,

Sigmoidal function is operating in the output neurons also, and the output of the *q*th neuron

*OHp <sup>I</sup> e*

= = <sup>=</sup> å 12,12

1, 1 *Hp mp Im m p*

{ } <sup>=</sup> { } *t t O I* (1)

*I VO* (2)

*I WO* (4)

(3)

output (O) of the input layer are the same:

196 Organic Farming - A Promising Way of Food Production

O*I,m* is the output of *m*th input neuron.

O*Hp* is the output of the *p*th hidden neuron

I*Hp* is the input of the *p*th hidden neuron and

to the *q*th output neuron I*Oq* is calculated as follows:

O*Hn* is the output of the *n*th hidden neuron and

*p*th hidden neuron as

neuron is given by

where

where

where

is given by

O*Oq* is the output of the *q*th output neuron

I*Oq* is the input of the *q*th output neuron and

θ*Oq* is the threshold of the *q*th output neuron which is initialized to zero in this system

#### **11.2. Training of the system**

A three-layered FFBPN was designed for this learning system. Three years data (Table 16) on various aspects of cultivation of EFY were used for training the system.


**Table 16.** Values used for training the learning system

Weight matrix obtained between input and hidden layers and between hidden and output layers is stored in the database and is used for making predictions with other input data-sets. This system learns about the EFY production system when the independent variables like weather parameters, soil and nutritional parameters of the system as well as the corresponding dependent variables of the system like com yield, canopy size, etc., are fed as input into it. Once it learns about a particular system pattern, it can predict the outputs corresponding to another set of independent variables of a similar pattern. The system can be trained for various independent–dependent variable patterns so that dependent variables for another set of same independent variables can be predicted accurately. When more and more inputs are used for training as well as prediction, the system learns more and its precision increases.

### **12. Constraints in promotion of organic farming**

In India, the availability of organic manures is a major constraint. It is estimated that to feed 1.4 billion population by the year 2025, a minimum of 301 million tonnes of food grains are needed. To meet this demand, it will be necessary to harness 30–35 million tonnes of NPK from fertilizer carriers and an additional 10 million tonnes from organic and biofertilizer sources [63]. Thus, only approximately 25–30% nutrient needs of Indian Agriculture can be met by utilizing organic sources solely [24, 64]. Organic manures are bulky (high cost of handling and transportation), of low analysis, slowly available and variable in composition. The availability of cattle dung for organic farming will be further limited as this is a major source of fuel in rural households. Apart from these, green manuring and recycling of farm wastes as manures have not become popular as these are more time and space consuming and their impacts on productivity are not rapidly discernible. At present, certification procedures are cumbersome and expensive [24, 64].

### **13. Future thrust**

Some of the future lines of action for promotion of organic farming have been identified [24, 64, 65]. Proper delineation and identification of prospective areas and crops (like tuber crops) may be helpful for effective promotion of organic farming. There is a need to undertake systematic research on the comparative values/advantages of organic farming over conven‐ tional farming on a long-term basis for promotion of organic farming. The package of practices recommendations for organic farming has to be popularized. The extent of availability of potential organic sources needs to be ascertained along with measures that may be helpful in improving the convenience of their use. Environmental impact, especially water and air quality effects, of organic farming needs to be assessed.

Weed management options particularly under climate change by nonchemical and biological methods are limited and need evaluation. The benefits accruing through organic farming on crop yield, quality, market preference and price advantage may be properly understood and promoted among the farmers and consumers [24].

### **14. Conclusions**

Weight matrix obtained between input and hidden layers and between hidden and output layers is stored in the database and is used for making predictions with other input data-sets. This system learns about the EFY production system when the independent variables like weather parameters, soil and nutritional parameters of the system as well as the corresponding dependent variables of the system like com yield, canopy size, etc., are fed as input into it. Once it learns about a particular system pattern, it can predict the outputs corresponding to another set of independent variables of a similar pattern. The system can be trained for various independent–dependent variable patterns so that dependent variables for another set of same independent variables can be predicted accurately. When more and more inputs are used for

In India, the availability of organic manures is a major constraint. It is estimated that to feed 1.4 billion population by the year 2025, a minimum of 301 million tonnes of food grains are needed. To meet this demand, it will be necessary to harness 30–35 million tonnes of NPK from fertilizer carriers and an additional 10 million tonnes from organic and biofertilizer sources [63]. Thus, only approximately 25–30% nutrient needs of Indian Agriculture can be met by utilizing organic sources solely [24, 64]. Organic manures are bulky (high cost of handling and transportation), of low analysis, slowly available and variable in composition. The availability of cattle dung for organic farming will be further limited as this is a major source of fuel in rural households. Apart from these, green manuring and recycling of farm wastes as manures have not become popular as these are more time and space consuming and their impacts on productivity are not rapidly discernible. At present, certification procedures are cumbersome

Some of the future lines of action for promotion of organic farming have been identified [24, 64, 65]. Proper delineation and identification of prospective areas and crops (like tuber crops) may be helpful for effective promotion of organic farming. There is a need to undertake systematic research on the comparative values/advantages of organic farming over conven‐ tional farming on a long-term basis for promotion of organic farming. The package of practices recommendations for organic farming has to be popularized. The extent of availability of potential organic sources needs to be ascertained along with measures that may be helpful in improving the convenience of their use. Environmental impact, especially water and air quality

Weed management options particularly under climate change by nonchemical and biological methods are limited and need evaluation. The benefits accruing through organic farming on crop yield, quality, market preference and price advantage may be properly understood and

training as well as prediction, the system learns more and its precision increases.

**12. Constraints in promotion of organic farming**

198 Organic Farming - A Promising Way of Food Production

and expensive [24, 64].

**13. Future thrust**

effects, of organic farming needs to be assessed.

promoted among the farmers and consumers [24].

In order to attain sustainable food-cum-livelihood-cum-environmental security in India, we may require an array of alternatives to chemical intensive agriculture. Instead of seriously debating on organic vs conventional agriculture it is better to examine critically the costs and benefits of the different alternative management options. It has been conclusively proved in tuber crops that organic management is an alternative viable option for sustainable and safe food production with less soil degradation and environmental pollution. Tuber crops, especially EFY and yams are prospective candidates for organic farming. EFY is the most responsive, followed by greater yam, white yam, lesser yam and taro. Generation of sufficient biomass, addition of crop residues, green manuring, farm waste recycling, fortification of manures through proper composting, adoption of crop rotations involving legumes, estab‐ lishment of biogas plants and development of agro-forestry for alternate source of fuels are some of the strategies that will help promote organic farming of tuber crops. These practices would help a great deal in supplementing/rationalizing the use of inorganic fertilizers, which cannot be totally eliminated in Indian Agriculture.

### **Author details**

Suja Girija, Sreekumar Janardanan, Jyothi Alummoottil Narayanan and Santosh Mithra Velayudhan Santhakumari

\*Address all correspondence to: sujagin@yahoo.com

ICAR-Central Tuber Crops Research Institute, Thiruvananthapuram, Kerala, India

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