In India, the Green Revolution increased not only the crop productivity but also the accumulation of plenty of persistent mutagenic, carcinogenic and teratogenic xenobiotic residues in the soil. During the green revolution era, agriculture was the backbone of the Indian economy. But now, there are also other sectors that act as a major source of economy and eventually agriculture practices have been ignored for several reasons. Population outburst, establishment of infrastructure and urbanization are the major impacts on minimal agriculture practices. In order to meet out the demand of food productivity, we are in need of modern agricultural practices which include inorganic fertilizers and pest control agents, as it is believed that Indian traditional agricultural practices may not yield much productivity. But what was the status of Indian agriculture before the Green Revolution? Sustainable agriculture productivity was attained with the help of available natural resources. Application of abundant quantity of inorganic inputs, plant growth promoters, weedicides and pest control agents paved way for the deterioration of agricultural soil. These chemicals are persistent in the environment for several years and in some cases it may be for several decades. These chemicals not only spoiled the agriculture field but also drastically contaminated most of the water bodies. Besides, xenobiotic compounds are biomagnified and accumulated in various parts of plants. Thus, the anthropogenic compounds enters into the living being where chronic accumulation of such compound in the liver, spleen, kidney etc causes lethal complications in living organisms and in human beings. Our systemic organs may not be able to metabolize all the chemicals and excrete it.
The sulphonated, chlorinated, nitrochemical and hydrocarbon based chemicals used in agriculture soil are carcinogenic in nature and it is extremely difficult to remove them from soil, moreover biodegradation of such chemicals require several decades. Agriculture water runoff into the water bodies results in the adverse effects on non-farming community. These compounds persist in the environment and may undergo chemical chelation, oxidation or reduction and enter into the water body as leachate. The adverse effects of such chemicals are numerous and causes acute to chronic diseases in living beings. Most of the chemicals are neurotoxic and severely affects the CNS (central nervous system). These chemicals not only decrease the fertility of soil but also have adverse effect on the fertility of living organisms. Genotoxicity is the other problem where the chromosomal aberrations lead to life threatening issues such as cancer.
Chemical inputs alter the fertility of soil. Inorganic nitrogen, phosphorous, potash, ammonium salts, sulphate, magnesium sulphate, calcium nitrate, trace elements such as zinc, boron, copper, iron, molybdenum, chloride, manganese are added into the soil to enhance the productivity. The positive and negative charges of these chemicals will have a strong adsorption or affinity with soil particles. The acidic or alkaline nature of soil is determined by the load of hydrogen ion concentration (pH). Therefore, continuous application of chemicals into the soil may alter the pH of soil. Once the soil pH is altered, the soil may not support the growth and productivity of desired crop. Therefore, the chemical inputs applied into the soil would not support the growth of plant and on the other hand inhibit the survival of soil – beneficial microflora. Most of the horticulture crops require acidic to neutral pH (between 5 and 7). Addition of chemical inputs in turn elevates (over 7) the soil pH and thus the soil may not support the desired cultivar.
Organic agriculture practices rely on various inputs such as cow dung, poultry manure, goat manure, pig manure, horse manure and various plant parts as compost. A great degree of variation could be seen in the composition of NPK values and other primary and secondary micronutrient content among the organic inputs. Besides, several plant extracts, spices and plant parts were found to be effective against various diseases and pests.
Bio-fertilizers, bio-control agents, bio-pesticides, PGPR, bio-fungicides and bio-immuno stimulants play a pivotal role on organic agriculture. These eco-friendly agents conserve the native flora and fauna, enhance the soil fertility and are not harmful to living beings. Supplementation of these inputs into the soil where organic carbon content is rich can increase the yield. In the rhizosphere region, the beneficial microbes colonize the plant root and help the plant to uptake nutrients, prevent the root from infectious diseases, induce root elongation and solubilize the insoluble fertilizers. A survey by an Indian company indicates that one metric ton (mt) of Rhizobium is equivalent to that of 100 – 400 mt of Urea with a saving of 50 – 200 mt of Nitrogen (N) (minimum N fixation of 50kg per hectare). Similarly, one mt of Azozpirillum or Azotobacter could replace 50 – 100 mt of Urea with a saving of 20mt of N. One mt of PSM (phosphate solubilizing microorganism) can substitute 100 mt of DAP (di-ammonium phosphate). Similarly, there are several PGPR (Pseudomonas fluorescens and Methylobacterium) that can reduce the use of Urea fertilizer and growth promoting chemicals and hormones.
Microorganisms are ubiquitous in nature and in fact they are the part of our life. Beneficial microbes such as bacteria, fungi and actinomycetes are the key players in agriculture. Many bio-fertilizers, bio-control agents, bio-pesticides, bio-insecticides and PGPR (plant growth promoting rhizobacteria) are extensively used in agriculture. The number of microbes per gram of soil differs from soil to soil as well as depth of the soil. Microorganisms are involved in bio-geo chemical cycles, plant growth promotion, hormone regulation in plants, immunity of plants and degradation of organic materials in the soil; the beneficial microbes approach the plant and interact with the plants, exchange chemical signals and regulate the plant growth. The chemotaxis mechanism of beneficial microbes is a mutual process not only with the plants but also among the microbial community. This sort of mechanism is very essential in the soil. But, the xenobiotic compounds could break this interaction and because of the toxicity the microbes cannot survive.
People may be aware of Refuse, Reduce, Reuse and Recycle, a “4R” principle, applicable for solid waste management. This strategy could be employed in Organic agriculture. Therefore, farmers who practices organic agriculture could Refuse to buy the chemical toxicants, if you are a beginner, you can Reduce the chemical inputs, if you have plenty of agricultural waste materials, you can compost it, and Reuse the plastics and finally you can very well Recycle it.
Organic agriculture never requires chemical inputs in your soil. There is no possibility of bio-transformation or bio-magnification or bio-accumulation of toxicants. So, we can preserve soil, water body and conserve the biodiversity. Let’s give life to the soil!