ADITYA and Dr. J N BHATIA
Vegetables are important constituents of Indian diet as they are a rich source of carbohydrates, proteins, vitamins, fibers, minerals, and antioxidants etc. Vegetables and fruits are consumed for nutrition, maintenance of health and many other therapeutic values that involve healing of number of diseases. The indiscriminate use of chemical inputs in agriculture concerns the contamination of food with agrochemicals, environmental pollution, soil, and water and therefore made us to think about an alternate form of agriculture practice to produce food that is free of contaminants. During the last two decades, due to increasing demand and awareness among people, organic agriculture has emerged as a dynamic and alternate farming system. Similarly, there has been a paradigm shift and interest to adopt organic vegetable production systems which are ecologically and economically viable along with being socially acceptable. Organic farming of vegetable production favors the maximum use of organic materials and discourages the use of synthetic agro-inputs to ensure conservation of natural resources and healthy environment. The goal of organic vegetable production is to optimize the health and productivity of independent commodities of soil, plants, animals, and people.
Food and nutritional security are therefore a serious global concern because by 2050 the population of India will cross more than 170 crores. The role of vegetables in nutritional security is immense hence the production of vegetables needs to be increased. Under the present context of global warming and climate change, organic farming must fulfill the twin objective of system sustainability and environmental protection.
Scope of growing organic vegetables:
India is blessed with various agro-climatic regions to produce many types of organic food. For sustainable production of vegetables, India is equipped with many types of naturally occurring organic form of nutrients that will enhance vegetable production in different parts of the country. India is having diversity in climates with 100-10,000 mm rainfall, desert, hill, strong traditional farming system-crop-tree-animals, innovative and progressive farmers, vast dry lands, and low use of chemicals. About only 40% of the total cultivable area is covered with fertilizers where irrigation facilities are available and in the remaining area, which is usually rain fed, negligible amount of fertilizers are being used. Farmers of that area use organic manure as a source of nutrients that are readily available either in their own farm or available locally. The area of 18 million hectares in north-eastern region of India provides a huge opportunity for organic vegetable production and less use of chemical inputs in cultivation process. Thus, India has tremendous potential to grow vegetables organically and emerge as a major supplier of organic vegetables in the world market.
As far as the availability of major organic nutritional inputs in India is concerned it is estimated that around 700 MT of agricultural waste is produced in the country which is either burnt or left inside the field. This implies a theoretical availability of 5 tons of organic manure per hectare land per year, which is equivalent to about 100 Kg N:P:K per hectare per year and as per the report of National Centre of Organic Farming – Ghaziabad Crop Residue (3.865 MT), Animal Dung (3.864 MT), Green Manure (0.223 MT) and Bio-fertilizers (0.370 MT) are available in India. Apart from that there are several other alternatives for supply of soil nutrients from organic sources like FYM, compost, crop residue, vermi-compost, bio-fertilizers and bio-agents etc. There are specific bio-fertilizers for vegetables that offer a great scope to further reduce the gap between nutrient demand and supply. Besides, there is enough scope of using bio-dynamics preparations like Jeevamrit, Ghanjeevamrit, Bharamastar, Bejaamrit, Neemastar, Agniastara and Bio-gas slurry. On farm production is the basis to meet the requirement of nutrients and to manage the prevalence of insects or pests in vegetables crops.
Nutrient management options for organic vegetables:
Sources of nutrients for organic vegetables:
- Green manure: Numerous fast-growing nitrogen fixing crops like dhaincha, sun-hemp, and cowpea may be used as green manures which can fix atmospheric nitrogen to the extent of 60-100 kg per hectare. Green manuring plays a vital role in improving soil health as well as it is also beneficial for production of organic vegetables. Besides adding nutrients into the soil, green manure improves the physical and microbial properties of the soil.
- Farmyard Manure (FYM): FYM is prepared by using farm waste, cattle urine, and dung. Application of FYM in the soil improves vegetable yield, physical properties of the soil, microbial activity and has residual benefits to succeeding crops.
- Enriched Compost: Composting of organic residue is generally the traditional source of nutrients for crops. Though the concentration of nutrients is quite low in compost, its special merit is its capacity to provide almost all essential micro-nutrients. The supply of micro-nutrients satisfies the hidden hunger in plants and safeguards it against any toxicity or injury. Besides the supply of nutrients compost, it also improves the physical, chemical, and biological health of the soil. Thus, compost can be further enriched by adding bio-fertilizers, microbial inoculants, and rock phosphate etc.
- Vermi-Compost:Vermin-culture technology is an aspect involving the use of earthworms as versatile natural bioreactors for effective recycling of non-toxic organic waste in the soil. They effectively harness the beneficial soil micro-flora, destroy soil pathogens, and convert organic wastes into valuable products such as bio-fertilizers, bio-pesticides, vitamins, enzymes, antibiotics, and growth hormones.
- Crop concentrated organic manure(Oilcakes): Oil cakes can be used for increasing the yield of vegetable crops. Before the use of fertilizers, the oil cakes are applied to the fields so that the nutrients present in them are made available to the crops. Addition of oil cakes in the fields will add large amount of organic carbon to the soil that will help in enhancing microbial activity. Castor cake, linseed cake and neem cake are some of the examples.
- Crop Residue: Use of crop residues is essential in organic vegetable production as they increase the organic matter content of the soil and maintain soil fertility thereby increasing the yield of vegetable crops substantially. Recycling nutrients like N, P, K, Ca, S, Cu, Zn, and Fe from plant waste can be obtained through scientific composting.
- Liquid manures: Application of liquid manure for enrichment of soil is very essential to maintain the activity of micro-organisms and life forms in the soil. Three to four applications of liquid manure are essential for all types of vegetables. Liquid manures such as Jeevaamrit, Ghanjeevamrit, Beejaamrit, cow urine and vermi-wash are excellent growth promoters when used as foliar spray for better growth yield and quality.
- Bio-fertilizers:A culture of micro-organisms is applied to the soil or seeds in order to increase fixation of nitrogen or release of phosphorus as they include biomass of certain plants which contains large quantities of nitrogen as a result of their association with nitrogen fixing organisms. Appropriate species of microbes have the capacity and capability of fixing atmospheric nitrogen in vegetables crops. Rhizobium spp., Azotobacter spp., Azospirillum spp., VAM, PSB Azolla and Pseudomonas spp. have been found to be highly effective tools of fertility management and biological nutrient mobilization.
- Agro-industrial wastes:Large numbers of agro-based industries are established in our country. They invariably produce large quantity of organic decomposable wastes which are rich in plant nutrients but are regarded as valueless waste. These organic wastes can be used to produce manure that can be used in the production of organic vegetables.
- Bioconversion of underutilized sources: Bio-gas slurry, poultry manure and by-products of slaughter houses i.e. bone meal, meat meal, leather wastes etc. can also be used in the organic production of vegetables that will meet out the nutritional requirement of vegetables crops.
- Cultural methods: Over the years of study, it has been observed that organic sources of nutrients supplemented with different cultural methods are more effective. These methods have been part of our agriculture since a long time and have been found to be highly effective in maintaining the soil health and they also keep the population of insect pest below economic threshold level. Important cultural methods include crop rotation, crop diversification, ideal intercropping, alley cropping practice of homestead farming, soil and water conservation practices, fallowing and establishment of vegetative bunds that play a tremendous role in the organic production of vegetables.
Benefits of organic farming in vegetable:
- Vegetable productivity of vegetable crops in organic farming is low in initial years but the yield increased progressively after 4-5 years.
- Organic carbon in soil has increased by 22 per cent under organic production over inorganic in six years (IIVR Annual Report, 2016).
- The increased organic matter content due to organic farming enhanced the population of soil microbes (Fungi, Bacteria, Actinomycetes) thereby improving the soil fertility and health.
- Addition of bio-fertilizers and bio-agents in soil has greater impact on agriculture and on the control of environmental pollution.
- Organic carbon builds up is noticed in organically fertilized fields in vegetables crops.
- The loss of nutrients in organic manure is less due to its slow release in the soil.
- Regular addition of organic fertilizers improves the soil quality.
- Continuous addition of organic manure in the vegetables assures a regular supply of micro-nutrients.
- A steady increase in positive balance of zinc, copper, ferric and manganese was recorded in organic vegetable plots as compared to conventional vegetable growing systems.
- Organic produce contains more vitamins, minerals, enzymes, trace elements and even cancer fighting antioxidants than conventionally grown vegetables.
- Organic farmers have greater diversity due to mandatory crop rotation and preferences for crop varieties with high tolerance to complex biotic and abiotic factors.
- Organic farming practices preserve soil fertility and maintain or increase the organic matter, thereby reducing the negative effects of drought while increasing productivity.
- Organic farming can potentially contribute mitigate threats from climate change on vegetable production.
- There is a tremendous scope of export of vegetables thus huge foreign exchange can be earned.