Inorganic Transformation of Added Phosphorus in Soil in Relation to Soil Characteristics and Moisture Regime

Transformation of added water soluble phosphorus was studied in five contrasting soils, both under field moisture and waterlogged conditions. Within 24 hours, most of the added phosphorus was recovered in different inorganic fractions in the order, Al-phosphate > Fe-phosphate > Ca-phosphate. Reductant soluble Fe-phosphate increased in red, late rile and hilly soils with no significant change in alluvial and saline soils. On aging, quantity of Fe-phosphate increased and that of Al-phosphate decreased irrespective of soil characteristics and moisture regimes. On the whole, Ca-phosphate did not change much except in alluvial and saline soils. It increased in saline soil and decreased In alluvial soil on aging. Aging caused increase in reductant soluble Fe-phosphatt in red and laterite soils and decreased in hilly soil. Though the general trends of the transformation process were identical under both the moisture regimes, the rate as well as the magnitude of shift in the amounts of various phosphate fractions were enhanced by higher moisture level.