Phosphorus Fractionation in Submerged Black Soil as Influenced by Different Phosphatic Fertilizers

A laboratory incubation experiment was conducted during December, 2017 to March, 2018 in Department of Soil Science and Agricultural Chemistry, College of Agriculture, Raichur, Karnataka, India to study the fractionation of phosphorus (P) in black soil amended with different phosphatic fertilizers under submerged condition. The soil were kept under subemerged condition for 90 days and phophatic fertilizers such as single super phosphate (SSP), diammonium phosphate (DAP) and mussoorie rock phosphate (MRP) alone or in combination with FYM  and PSB  added through 13 treatment combinations. The soil was analyzed for various inorganic P fractions (saloid P, Al-P, Fe-P, RS-P, occluded P,Ca-P) for 90 days at definite intervals. The results showed that calcium bound P (Ca-P) was the dominant fraction in submerged black soil whereas saloid P recorded as the least dominant fraction. It has seen that application of phosphatic fertilizers significantly increased all the P fractions over control. All the forms of P viz., saloid P, aluminium phosphate (Al-P), iron phosphate (Fe-P),reductant soluble P (RS-P) and occluded P were higher for DAP treatment along with FYM and PSB as compared to SSP and MRP whereas application of MRP along with FYM and PSB recorded significantly higher Ca-P during the incubation period. All the fractions of P were significantly higher at 1st day of incubation after which it decreased with passage of incubation time.