P. KALAISELVI AND S. MAHIMAIRAJA
Abstract
The effect of different levels and methods of spentwash application on soil phosphorus dynamics was examined through a field experiment using Groundnut (Arachis hypogea L.) as a test crop. The changes in the concentration of different fractions of phosphorus, namely labile water soluble phosphorus, labile adsorbed and exchangeable phosphorus, organic phosphorus and acid soluble calcium bound phosphorus in soil were measured by a sequential phosphorus fractionation procedure. The increase in the rate of spentwash application remarkably affected the concentration of different phosphorus fractions in soil. The result of fractionation study showed that in addition to spentwash inorganic phosphorus, 82 to 96 per cent of mineralized phosphorus was mainly originated from the dissolution of soil apatite phosphorus which was effected by the organic acids produced during the decomposition of organic matter (soil and spentwash).