Because of indiscriminate use of chemical fertilizers for decades the organic matter content of soils has come down to less than 1 per cent. In addition, the use of pesticides led to pest resurgence and difficult-to-control weeds species.
The residues of the chemicals cause concern over the safety of food and sustainable production. The addition of chemical fertilizer like nitrogen in plant caused an infant disease like methanoglobinaemia.
Hence, the expectation that organic farming by reverting to the use of manures, green manures, urban waste, rural wastes, etc. can bring sustainability to agriculture with eco-friendliness. Hence, it becomes imperative for the researchers and planners to develop an alternative viable strategy to supplant the chemical farming.
Organic farming is a production of crops which avoids or largely excludes the use of synthetically compound fertilizers, pesticides, growth regulators and live-stock feed additives. To the maximum extent feasible, organic farming systems rely upon crop rotation, crop residues, animal manures, legumes, green manures, off-farm organic wastes, mechanical cultivation, mineral bearing rocks and aspects of biological pest control to maintain, soil productivity and to supply plant nutrients and to control insects, weeds and other pests.
To develop a sustainable agriculture system for guaranteed adequate food production in the foreseeable future.
To develop self-sufficient agriculture system which would rely as much as possible upon resources from within its own resources.
Pure organic farming: It includes use of organic manures, and biopesticides with complete avoidance of inorganic chemicals and pesticides.
Integrated Farming: It involves integrated nutrient management and Integrated Pest Management.
Integrated Farming Systems: In this type, local resources are effectively recycled by involving other components such as poultry, fish pond, mushroom, goat rearing etc. apart from crop components. It is a low input organic farming.
Fertilizers used for organic farming:
The major sources of organic plant nutrients in India are farm yard manure, rural and urban compost, sewage sludge, pressmud, green manures, crop residues, forest litter, industrial waste and by-products.
The number of biofertilizers such as blue green algae (BGA) and azolla are used extensively to meet the nitrogen demand of the crop. Small quantities of powdered neem cake are also used. These organic nitrogen supplements unlike the fertilizer nitrogen do not suffer any loss in the fields.
Phosphorous-solubilising and mobilising organisms such as phosphobacterium and vesicular arbuscular mycorrhizae (VAM) are quite helpful in meeting the phosphorus demand of the crop. Potassium for the crops can be supplied by using potassium rich organic amendments such as burnt rice,, rice straw composted using tricoderna harzianum and composted coconut coir pith.
Effect of Organic farming on Crop yield and quality
Field experiments conducted in Annamalai University to study the impact of organic farming of Rice yield and quality, the results of the study clearly indicated a positive approach towards practicing complete organic farming in attaining premium quality produced with higher grain yield.
Application of 75 per cent N through FYM and 25 per cent N through NC produced the largest rice grain yield - 6.13 t/ha compared to the yield obtained with recommended fertilizer schedule (100:50:50 kg N, P2O5, K2O/ha the yield being 4.3 t/ha). Quality characters viz., milling recovery, head rice percentage, protein percentage also were significantly higher with organic sources.
Whereas study carried out in Japan to know the effect of organic farming on soil properties, it found that with time, there was an increase in organic matter content, soil reaction, exchangeable CaO and MgO, available phosphorus and trace elements of manganese and boron. However, the potassium content was erratic.
The soils using poultry manure compost for more than 10 years showed much accumulation of calcium and available phosphorus and a serious imbalance of bases.