Abstract

The Research Institute attached to the Agricultural College, Coim- batore has analysed samples of soils in the Tanjore Delta taken at five miles apart. It has been found out that phosphates are wanting in almost all the samples of soils analysed. "A soil containing about 700 lbs. of available phosphates per acre within the first 9 inches would probably show about 3000 lbs. of total phosporic acid both available and unavailable to the plants. Of the 700 lbs. of available phosphates, a crop of 1000 lbs. of rice per acre removes from the soil only 3 lbs. to the husk, 4 lbs. to the rice and 3 lbs. to the straw. The gain of phosphoric acid by silt deposition is a good deal more than the outgoings and it is only where no silt deposit takes place that the question of recoupment of phosphoric acid would be considered."

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