Conservation Agriculture
Striking balance between farming and environment
Farms are part of our environment
Agriculture is still the mainstay of our economy. It is considered part of our environment, although man-made. But of late it is conflicting with environment more often than not. While urbanization under rising population pressure is encroaching upon existing farm lands, agriculture is encroaching on the already constrained forests to produce more for feeding the growing number of mouths, besides also polluting the environment in its on process. However, we cannot reduce agricultural activities to conserve environment, nor we can destroy environment for the save of agriculture. We have to strike a balance. Agriculture was developed about ten thousand years ago when women started digging soil by hand tools for sowing seeds. Later ploughs were developed for tilling lands. After the invention of steam engine, mechanised cultivation with tractor started in 1868. With population increase, more and more forest lands were brought under cultivation in almost all countries of the world. Big power-operated machine enabled farmers to break the soil fine by repeated tilling. When soil is made fine, it is prone to wind and water erosion, which carries away fertile top soil. One of the very serious results of this kind of poor tillage is the Dust Bowl, which made severe ecological damage to American and Canadian prairie lands from 1930 to 1936 (in some areas until 1940). It affected 400,000 sqkm of parts of Texas and Oklahoma, and parts of New Mexico, Colorado and Kansas. Two and a half million people had moved out of the plain states. However, farmers of affected areas adopted conservation tillage (CT) that reduced tillage or ploughing and maintained a residue cover on the soil. No-tillage or zero-tillage, direct-drilling, minimum-tillage and/ or ridge tillage practices have some kind of conservation effect, therefore, are included in the CT. Moreover, the system conserves time, fuel, earthworms, soil water, soil structure and nutrients. Conservation agriculture is a recent concept, which has been developed to conserve the environment. It may be defined as minimal soil disturbance (no-till) and permanent soil cover (mulch) combined with rotations, as a more sustainable cultivation system for the future. In this system of agriculture, resources are saved as much as possible for crop production. When soil is not tilled, minerals are maintained within the soil, erosion is stopped and water loss occurring in the soil is contained. Tillage destroys organic matter that can be provided within the soil cover. In no-till farming, soil remains productive for longer period of time. Permanent soil cover in CA allows growth of organisms within the soil surface. Breaking down of mulch produces a high organic matter level that acts as fertilizer. In fact soils become renewable resource, which means that whatever is taken out of the soil can be put back into the soil over time. Ploughing increases the amount of oxygen in the soil and increases the aerobic process that hastens the breakdown of organic material. As crop rotation is practiced in CA, it acts as a natural insecticide and herbicide against specific crops. It optimises production utilising all modern technologies to protect the environment. With zero tillage and direct drilling, the only tillage operation is minimum disturbance of soil for applying seed and fertilizer directly into the stubble of previous crops. Organic matter content of the surface layers of no-tilled land increases gradually, which is very important for Bangladesh soil as its average is less than one against the desired level of two. Also zero tillage improves soil structure, water use efficiency, soil biology and nutrient cycling. Though modern agriculture is one of the major contributors to environmental pollution, without it sufficient food cannot be produced for the ever-growing population. Because of so much development of high yielding varieties of crops, livestock and fisheries and related technologies, it is now possible to produce more food from less land. Yet every year more and more forest and fallow lands are brought under cultivation. It is of urgent need now to produce crops in such a way as pollutes the environment to a minimum level and there occurs little encroachment. Conservation agriculture helps in the promotion of the environmental integrity of the soil systems. Stability of the soil organic matter enhances sequestration of carbon and contributes to mitigation of climate change. About 75% less fuel is used for tillage operation, therefore, greenhouse gas emissions are further reduced. Zero tillage is practiced in more than 95 million ha land worldwide of which 47% is practiced in South America, 39% in the USA and Canada, 9% in Australia and about 5% in the rest of the world, including Asia, Europe and Africa. But adoption of CA is not so easy. To practice it, farmers initially have to incur financial loss due to less crop production and also for purchasing new type of planter or seed drill. CA is based on establishing an organic layer and producing its own fertilizer, which needs several years. During that period, crop yields will be lower than conventional agriculture. Due to various reasons, many countries cannot produce enough food to feed its own people every day. Therefore, every government tries to produce sufficient food exploiting soil, water and all other resources. As production is reduced during the conversion of lands to CA, it may not be very appropriate for Bangladesh to opt for mass-scale conversion to CA. As two to three crops are grown from the same lands every year throughout the country, soil fertility, in general, is deteriorating every year. When CA will be practiced, soil fertility will improve slowly. Therefore, demonstration could be conducted in limited area with limited number of crops. For the last few years, Bangladesh Agricultural Research Institute has been conducting research on CA. As a part of that, scientists are working on the development of power tiller operated minimum tillage seeder, zero-till drill, strip tillage seeder and bed planter, all of which have shown positive results. Farmers have shown more interest in minimum tillage seeder for sowing wheat after transplanted aman rice. With the seeder, wheat seeds can be sown immediately after harvesting rice, which can avoid late sowing (sown after 30 Nov.) of seeds that causes yield loss of 40 to 44 kg/ha/day. The method also saves fuel and labour cost required for tilling 3-5 times in conventional tillage practices. The problem of late sowing as well as yield loss can be minimised if minimum tillage seeder is used. It is expected that CA will be adapted to a limited scale in Bangladesh that will reduce cultivation cost and help in environment protection to some extent. Then it may be practiced full sale, if found appropriate, to yield both crop and protect environment to optimum extent.
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