Relative agronomic efficiency of rock phosphate in red (Typic Haplustalf) soil

摘要

One of the major problems of acid soils is the low availability of both native and applied phosphate due to the dominance of Fe~(3+), Al~(2+). Indigenous rock phosphate was reported beneficial as a source of P in acid soils. Response of rock phosphate is dependent on its source, chemical reactivity, nature of soil, phosphate fixing capacity and nature of amendments applied etc. It is also reported that Udiapur rock phosphate (URP) could profitably be used for acid soils (Misra, 1992) if powdered finely to pass through 100 mesh sieve and was as effective as SSP. Conjunctive use of elemental sulphur (S_o) / phrites / organic manure is proved successful in improving the effectiveness of RP even in neutral, saline and alkaline soils. Meagre informationis available on the use of rock phosphate with elemental sulphur. This study was therefore aimed at developing sulphur based rock phosphate fertilizer and evaluate its effectiveness on crops (Onion, black gram) and soil.