RESEARCH

Composting - An Organic Farming Technique for Sustaining Soil Nutrition in the Long Run.

The aim of organic farming is to produce pollution free nutritious food which would otherwise cause health hazards in human beings. All the available farm resources are used in this technique. The use of chemical fertilizers and pesticides are normally kept outside the arena of organic farming. Protection of eco-system is also a major perspective of this technique. In the context of organic farming there are a number of options available to the grower from which they can select and supply to the crop plants for meeting the nutritional requirement of crop plants. The source may be farm yard manure, poultry manure, leaf mould, compost etc. These substances contain nutrients in variable amounts. These are also called bio-fertilizers which are micro organism based. The various types of microorganisms help in releasing and fixing of nutrients in the soil to make the nutrients available to the plants. As these bio fertilizers are of organic in origin and are termed as organic fertilizers. Compost is one of the most important organic fertilizer which to which attention is needed when the soil nutrition is largely destroyed by the wide use of inorganic fertilizers by the farmers.

For converting the organic substances present in the organic wastes, crop residues and other degradable organic matters into available form to the plants it needs to be composted. Compost is the product of a microbiological process by which the bio-degradable organic wastes are converted to humus by the action of soil born micro-organisms.

The farm refuse and the town refuse are the two types of sources for composting. The farm refuse includes crop residues, wastes of biological origin etc. On the other hand town refuse includes wastes collected from the town of biological origin, which can be degraded e.g. night soils and dust bean collections.

The following table shows the per cent of plant macronutrient in five heavy organic manures which are extensively used.

Sl No.	Type of manure	Nitrogen (%)	Phosphate (%)	Potash (%)
1	Farm Garbage	0.5-1.5	0.4-0.8	0.5-1.9
2	Compost (town)	1.2-2.0	1.0	1.5
3	Compost (rural)	0.04-0.8	0.3-0.6	0.7-1.0
4	Cow dung gas plant byproduct	1.6-1.8	1.1-2.0	0.8-1.2
5	Green Manure (Sesbania bispinosa)	0.62	0	0

There are two most popular as well as easy methods of composting. These are i) Indore Method and ii) Bangalore Method. In Indore method digging of a pit near the cattle shed is done. Shredded bits of crop residues are placed on the pit. Over it a layer of cow dung is spread. Water is sprinkled over the mass. Until the height of the pit becomes one foot this process is continued. To protect the pit from rain a shed is made. Upside down turning is done in an interval of 15 days. The compost becomes ready in about 4 months. In Bangalore method the heaping is done exactly following the Indore method and after that the entire heap is covered with mud plaster. As a result of that temperature is increased due to anaerobic fermentation. The compost becomes ready in 8 months.

If the heap contains more amounts of cellulose and lignin degradation takes comparatively higher time. To shorten the length of time period of composting, inoculants of some decomposing organisms can be added to the composting substances in the heaps. As for example to decompose cellulose the organisms which can be used are Trichoderma viridi, Trichurus spiralis and Paecilomyces fusisporus. The lignin decomposers are Polyporus giganticus, Paecilomyces sp, Chaetomium globosum Tyromyces palustris and Poria placenta. These materials are to be added at the rate of 500 g mycelial mat/ton of material can have 10% higher decomposition.

Apart from the above techniques discussed above NADEP method and phospho-compost methods are also used. 

Today time has come to totally focus on organic farming technique when the price of inorganic fertilizers are so high and supply is also scarce in the fertilizer depots especially in West Bengal. The farmers of Midnapur, Burdwan, Bankura and 24 Parganas are finding it very difficult to procure fertilizers due to the above fact. Moreover, the greedy sellers are also forcing the farmers to purchase micro-fertilizers along with their required amount of fertilizer. Hence the only way to the farmers is to find the alternative source of soil nutrient supplier. Composting is a very easy technique which can be adopted by even the illiterate and ignorant farmers. In addition to that it will not destroy rather enhance the nutrient in soil for years to come.

References:
1. Alexander, M.(1977). Introduction to Soil Microbiology, 2nd edn. John Wiley and Sons, New York.

2. Brady, N.C. (1966). The Nature and Properties of Soil Science, 10th edn., Prentice-Hall of India Pvt. Ltd., New Delhi

3. Das, A.K.(2007). Organic Farming Methods for Medicinal Plants Cultivation in Orissa, 1 st edn,OUAT, Bhubaneshwar-3.

4. Ramamoorthy, B. and Velayutham, M. (1972). Soil Fertility and Fertilizer Use in India. Indian Farming. Vol. XXII (6) : pp. 80-84.

5. Subba Rao, N.S.(1982). Biofertilizers in Agriculture, Oxford and IBH Publishing Co., New Delhi

6. Tisdale, S.L. and Nelson, W.L. (1970). Soil Fertility and Fertilizers. The MacMillan Co.,London.