Abstract

                                The use of organic manures in crop production is known from time immemorial. Organic manures include different oilcakes with nitrogen content ranging from 2-5 to 6-2 per cent and organic waste of animal origin like dried blood, slaughter-house refuse and fish manure, where the nitrogen content ranges from four to ten per cent. But the largest source of organic manures comprise farm yard manure, compost and green manure. These bulky organic manures, which contribute to a great deal to the organic matter content of the soil, are very necessary for soil fertility. In cultivated soils of the tropics and subtropics the organic matter content is very low because of the rapid and continuous oxidative decomposition taking place. If crop production has to be maintained, the loss of organic matter has to be periodically supplemented to keep up the organic matter content in the soil which is very necessary for soil fertility.

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