The philosophy of sustainable agriculture is to maximize the crop production through scientific methods of farming, growing crop varieties of high-yielding and high-quality potentials and using optimum inputs of manures, fertilizers, bio-fertilizers and agricultural chemicals, without exploiting and polluting the natural resources of soil, water and environment.
Commercial agriculture at high levels of crop production with high quality produces would become sustainable if the following principles of integrated agriculture were adopted.
- High-yielding and high-quality varieties of crops must be grown.
- Improved agronomic practices from suitable land preparation to efficient harvest management must be adopted.
- Integrated soil fertility management practices to improve the physical, chemical and biological properties and fertility status and productivity of the soils using organic manures, fertilizers and bio-fertilizers must be followed.
- Adoption of
- efficient soil + crop-oriented water management,
- cost-effective environment-friendly weed control measures,
- integrated and effective pests and diseases control measures,
- conservation of natural resources like soil and water, and
- environment protection by avoiding pollution of natural resources of soil, water and atmosphere.
In the recent years, in an overzealous pursuit of organic farming with concern for protecting the environment, use of fertilizers and agricultural chemicals is often discouraged, and it is advocated to supply all the plant nutrients through organic manures only. Total organic farming may be a desirable proposition, but is not feasible to practise and sustain at high levels of crop production in modern commercial agriculture as we do not and cannot have enough organic manures to meet the requirements for all our arable lands.
Total organic farming would be possible only under subsistence farming as practised in our country under traditional low-productive agriculture a few decades back. It might also be possible under certain special situations like horticultural farming where sufficient organic manures like FYM or composts would be available for recycling and where the consumer would be ready to pay extra premium prices for the ‘green products’ to compensate for their comparatively lower productivity and higher cost of production.
Food security of our ever-growing population has been made possible in our country by increasing the food production from about 50 million tonnes in 1950 to more than 220 million tonnes now, by raising high-yielding varieties of crops, adopting Integrated Nutrient Management practices involving both manures and fertilizers and controlling the pests and diseases through Integrated Pest Management practices. At this juncture, it would be unwise and unremunerative proposition to cultivate crops without fertilizers using manures alone. What is needed is a judicious combination of organic manures and fertilizers and not exclusive use of either.
Organic versus Inorganic sources of Nutrients
The plants absorb all the nutrients in the inorganic ionic forms only, irrespective of the sources through which they are supplied. They can not differentiate between the nutrients supplied through manures or fertilizers. The nutrients supplied through the organic and inorganic sources do not function differently within the plant. The nutrients from the organic and inorganic sources differ only in their relative availability for the crop uptake. The nutrients from the fertilizers are readily available as most of these are in water-soluble forms. The nutrients supplied through the organic manures will become available for the crop uptake slowly but for longer duration due to slow decomposition rate of the manure and consequent gradual release of the nutrients, through mineralization into the labile pool. Once released, the nutrients from both the fertilizers and manures would behave similarly in the soil passing through the usual chemical and biochemical transformation reactions.
Quality of Crop Produces
It is true that the quality of the agricultural produces, particularly horticultural produces like flowers, vegetables and fruits, improves when the nutrients are supplied through the organic manures than in the forms of fertilizers. This is because of the supply of all the growth principles like enzymes, hormones, growth regulators, etc., besides all the essential plant nutrients from the manures. As a result, the metabolic functions are regulated more effectively resulting in better synthesis of proximate constituents like carbohydrates, proteins, fats, oils etc., leading to improvement in the quality of the produces.
Fertilizers would supply one or a few nutrients only and not the growth principles like enzymes, vitamins and growth regulators, which are essential for the improvement in the quality of the produces. This is the reason for the better quality of the produces obtained with the application of manures and not due to differences in the nature and properties of the nutrients supplied through manures and fertilizers.
The distortion in soil fertility and deterioration in soil health are due to improper and indiscriminate use of fertilizers, exclusively supplying a few essential elements like nitrogen, phosphorus and potassium only irrespective of the status and availability of these nutrients in the soil. These lopsided fertilization practices have led to imbalances in the status and availability of plant nutrients due to excess of certain nutrients and deficiencies of some others. This distortion in soil fertility can be corrected only with proper and judicious manure – fertilizer schedules based on soil fertility evaluation results.
Neither inorganic nor organic integrated Ways
Intensive agriculture on commercial high-productive scale cannot be sustained for long through total organic farming. It is because yield levels will come down drastically without fertilizers, as the demands of the crops for certain nutrients like nitrogen, phosphorus and potassium in comparatively higher amounts can not be met with the organic manures alone. Although indiscriminate use of fertilizers and chemicals has a potential for polluting the environment, it does not warrant exclusion of fertilizers altogether from the soil fertility management programmes, as the consequences of such withdrawal of fertilizers from soil fertility management will be disastrous.
Integrated Soil Fertility Management
Integrated Soil Fertility Management using manures, fertilizers and bio-fertilizers will facilitate restoration, improvement and maintenance of soil fertility, which will guarantee agricultural production at higher levels with high-quality produces as well. Agriculture at high levels of productivity could be sustainable only through such integrated ways using manures, fertilizers and bio-fertilizers in judicious combinations. It will also safeguard the environment and natural resources from being polluted and exhausted.
The philosophy of sustainable agriculture will become a bitter irony, if fertilizer use is reduced or excluded in the name of quality improvement of produces or environment protection, as such exclusion would lead to subsistence farming over the years in the near future. So, we must rediscover our green renaissance through integrated soil fertility management practices involving manures, fertilizers and bio-fertilizers to ensure and sustain environment-friendly high-productive, good – quality agriculture not only during the present generation but also during the future generations. Neither organic nor inorganic but ISFM ( Integrated Soil Fertility Management ) must be the set rule of sustainable high-productive, good-quality agriculture, if we are to ensure Food Security which will form the foundation for the National Security in the years to come.
by Dr. K. Kumaraswamy
formerly Professor of soil science & Agrl. Chemistry, Tamil Nadu Agricultural University, Coimbatore
(Published in The Hindu)