Abstract

To maintain the food supply for an ever increasing population every endeavour for conserving the essential elements of soil fertility will have to be made, more so, in these days of acute food shortage. The productive power of soils is steadily reduced when successive crops are grown and no adequate manuring is made. Organic matter is the sheet anchor of soil fertility in this tropical climate. The soils in almost the whole of Madras Presidency are generally deficient not only in organic matter but also in nitrogen. (1) For replenishing the organic matter depleted from the soils green manuring is the cheapest way. Green leaf manures not only supply essential plant nutrients but also improve the physical structure of the soils. The oxidation of manures resulting from the decomposition of green manures is said to assist the rendering of elemente already in the soil more available as plant food and has a stimulating effect on the activities of beneficial organisms. Green manure in combination with phosphate ferti lisers was found to yield best results in several places notably at Agricultural Research Stations, Samalkot and Manganallur (2). Among phosphatic manures the results with superphosphate and bonemeal was found to be encouraging in their direct and residual effects. Hutchinson and Milligun (3) showed that the addition of superphosphate to green leaf promoted its decomposition better even in a season when the moisture content is not high enough to allow of rapid decomposition of the green manure crop. Work at Puss indicated that under natural conditions phosphates in organic combination became more available to plante. To test these findings at Anakapalli and to find out:

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