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Vol. 6 No. 4 - October 2000

Organic Cultivation

By H.M. Behl

According to David Pimental of Corneall University, USA, 67 million birds are killed annually in the USA from direct impact of pesticides. Pesticides pose dangers to the biodiversity; health and well being of humans, animals and plant life; and are detrimental to soil micro-flora, micro­fauna and soil health. Developing nations like India have to procure these pesticides by paying precious foreign exchange. However, there are unknown dangers in this chemical recipe. Is this chemical cocktail indeed a necessary evil? Perhaps not.

In a natural ecosystem, there has to be a harmony between food, forests, human population and grazing population (in biological language, we say producers and consumers). Increase in the number of consumers beyond the carrying capacity of the land and need to export more for financial gains, motivates the communities to produce more. Increased and unmanaged production results in poor productivity per unit area, imbalance in the soil-water-microbes system, degradation of soil sites and irrational land use systems.

Green revolution vs. Sustainable green revolution

Improved varieties, and methods of cultivation, can increase productivity, however, chemical fertilizers and chemical pesticides changed the agriculture scenario in the world. Varieties that respond to chemical fertilizer inputs were selected for higher productivity. Irresponsible methods of cultivation and increased use of quick release chemical fertilizers, over irrigation rendered the soil unfit (not necessarily deficient in total nutrients but deficient in available nutrients) for cultivation. A higher input of fertilizers was practiced. However, there is a limit to application of fertilizers that soil can transmit to the crops or the crops can accept. Thus so-called "Green Revolution" was not a "Sustainable Green Revolution". The quick release fertilizers don't involve the microbes and don't follow the natural system of uptake. Such an uptake is a luxury intake. The so-called 'degraded soil sites' are actually man made. Decrease in production and productivity are thus our own creation.

Unhealthy Crops

Intensive cultivation, degraded soil sites, selection of varieties that are dependent upon quick release fertilizers and unmanaged high input agriculture or horticulture invites an array of diseases. Insect pests, fungal-and viral infections further decrease productivity and result upon chemical fertilizers and pesticides. The farmer is no more able to take his decisions and is dependent upon chemical fertilizers and pesticides.

Chemical pesticides are toxic, non renewable, non degradable, lethal and stay in the environment for many years. Many of these can stay in the body for several years and cause serious diseases. These chemicals kill the entire spectrum of microbes including the friendly ones. Chemical pesticides are a 'slow release nuclear' bombs' that have far reaching lethal effects than we can apprehend.

Higher application of chemical fertilizers results in higher imports, higher costs of production, transportation and overheads. It results in erosion of local resources and poverty. The technology meant for increasing food production becomes, in the long run, a cause for poverty, ecological imbalance, un­sustained development and disharmony between man and his environment.

Organic Cultivation

There are several aspects of Organic Cultivation. A planned Organic Cultivation will involve site specific and crop specific decisions. The manager has to plan Organic Cultivation at a specific site taking into consideration local resources, status of the environment, community involvement including demands from the cultivation project. However, two of these aspects, fertilizers and pesticides are very crucial.

Organic Pesticides

Supporters of chemical pesticides claim that there is no option but to use these lethal pesticides. It is surprising that though we are aware of several phytoactive metabolites from the scientific body of knowledge as well as from the knowledge available in Vedic literature, yet the society has patronized chemical pesticides. Commercial gains, quick success, impatience and ignorance has led to wide spread use of toxic chemical fertilizers. The losses to living organisms, microbes, environment and crops are ignored for the apparent commercial gains.

Search for environmentally safe pesticides received an impetus in early 1960s following the publication of 'Silent Spring' by Rachel Carson in 1962. Out of 1000s of plants with bioactive properties, neem tree (Azadirachta indica A. Juss), the Nimba, as is known in Sanskrit language, provides pesticidal options that are par excellence. The chemicals present in neem are safe, biodegradable and are environment friendly. Vedic literature particularly Atharva Veda, Ghryhasutra , Sutragrantha and Puranas provide a wealth of information on neem. Brihat Samhita, the Hindu treatise associates neem plantation with constellations. Long before synthetic chemicals and commercial insecticides and fertilizers were available, neem derivatives were used in Indian villages to protect and nourish crops. Today through scientific researches we know that neem extracts can influence nearly 400 species of insects.

Neem plants, as do all other plants, contain several thousands of chemicals. Of special interest are hundred of terpenoids that are unique to neem and some related members of this family. Of its biological constituents, the most active and well-studied compound is Azadirachtin. However in most traditional preparations of neem as pesticide or medicine, a mixture of neem chemicals are present and provide the active principles.

Neem is quite effective against armyworm, one of the most devastating pests of food crops in the western hemisphere. Azadirachtin in extremely low concentrations-a mere 10 mg per hectare-inhibits the pests. Neem extract is useful against leaf-miner, a serious pest in parts of North America. Neem seed extract has been approved by the US environmental protection agency for use on leaf miners. Neem is extremely useful as an anti-feedent and ovi-positional repellent for protection of crops like tobacco, groundnut, cotton and sweet potato from the damages caused by tobacco caterpillar or tobacco cutworm, a serious polyphagous pest of several crops.

Neem is also effective against fruit flies. Spraying neem can control med fly, one of the most damaging horticulture pests. Whereas conventional pesticides will kill fruit flies as well as thrips and internal parasites, neem products on the other hand leave the friendly organisms unaffected. De-oiled neem cake (the residual remaining after the oil has been pressed out of the seeds) and neem oil are quite effective against rice pests. Five applications of a 25% oil emulsion sprayed with an ultra low-volume applicator can protect rice crops against brown plant hoppers. Neem products greatly reduce the tungo virus transmission efficiency of green leathopper in rice. One of the traditional uses of neem in Asia has been for controlling pests of stored products. Farmers usually mix neem leaves with grain before keeping it in storage for several months. Neem leaves, oil or extracts act as repellent against several insects such as weevils, flour beetles, bean-seed beetles and potato moths. Treatment of jute sack by neem oil or azadirachtin-rich-products prevents the penetration of pests like weevils and flour beetles. Neem oil destroys bean- seed beetles (bruchids) - variety of insects mostly attacking legumes -at the egg-stage itself.

Organic Fertilizers

Organic fertilizers include application of agriculture waste, composting using earthworms, farmyard manure etc. However, microbes play a vital role in facilitating uptake of nutrients in a crop. Rhizobia among several of these mocrobes are quite popular for leguminous crops. Rhizobia and blue green algae fix atmospheric nitrogen and reduce dependency upon artificial application of chemical fertilizers. Mycorrhizae, the fungal organisms, facilitate P uptake.

Pseudomonas and several other bacteria facilitate nutrient uptake and form a very friendly network around the roots. Symbiotic organisms form a harmonious environment in the soil. There have been several researches worldwide to show that these are very friendly organisms. These organisms are usually available in the soils, more abundantly in the tropical climates. The local crop manager has to identify these microbes, select and multiply in sufficient quantities for applications. It empowers the local community to use its own resources in terms of biodiversity resources and rights, saves on application of high cost fertilizers, renders the soil healthy and avoids interference with the environment. The crop productivity can be optimized in the given environment.

Indian farmers have traditionally used de-oiled neem cake as a fertilizer in their fields. The dual activity of Neem cake as fertilizer and pest repellent has made it a favoured fertilizer. When neem cake is ploughed into the soil it also protects plant roots from nematodes and white ants. Farmers in southern parts of India puddle neem leaves into flooded rice fields before the rice seedlings are transplanted.

Neem cake has been successfully used for organic cultivation of bananas. It protects banana rhizome from infections and also serves as a ferfilizer. Unbelievable, but no pesticides are then required. For cash crops such as turmeric, sugarcane, banana and cardamom, 200 kg per hectare of Neem cake is applied. For black peper and betel vine 250 g per plant is applied. Neem cake is also extensively used for citrus trees, jasmine, roses and vegetable crops as organic manure. 100 kg of Neem seed cake will provide nearly 3.6 kg to N, 0.8 kg of P, 1.7 kg of K, 0.77 kg of Ca and 0.75 kg of Mg. Cases where urea application is unavoidable, coating of urea with neem extract prevent denitrification and increases urea efficacy.

Organic cultivation is an integrated crop management. Selection of elites among local cultivars or land races, producing hardy seedlings, applications of bio-fertilizers, microbial management, application of vermi-compost, practicing bio-pesticides, intercropping of 'protective' or symbiotic grasses, herbs or weeds are all components of Organic Cultivation.

Government of India, as also many other countries, provide accreditation as labeling for household and other consumer products, which meet the set environmental criteria. The ECOMARK logo is an earthen pot.

Organic cultivation is a beginning. In fact, we are re-discovering it since this was the form of cultivation from Vedic times to recent India. Indian agriculture of the past 5000 years was not Petro-chemical based agriculture rather an organic agriculture. Let us revert to Vedic Organic Cultivation; it may be agriculture, horticulture, silviculture or kitchen gardening.

Dr. H.M. Behl is Deputy Director & Head, Biomass Biology Division at the National Botanical Research Institue, Lucknow & Executive Editor of EnviroNews


This article has been reproduced from the archives of EnviroNews - Newsletter of ISEB India.


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