Forms of Soil Phosphorus and Depth Wise Distribution under Organic and Inorganic Nutrient Management in a Vertisol Planted Rice

To study the effect of organic and inorganic fertilization on depth wise distribution of different forms of phosphorus in Vertisol was performed on Vertisol under rice crop on soil samples obtained from the ongoing long term fertilizer experiment (LTFE) project. The P status of the different soil P fractions (salod-P, Al-P, Fe-P, Red-P and Ca-P) were analyzed from 0-15 cm, 15-30 cm and 30-60 cm in soil depths. All P fractions were higher in surface layer than that subsurface layer. The sequential order of dominance of different forms of P were Ca-P > Red-P > Fe-P > Al-P > saloid-P in Vertisol. The highest value of P fractions were recorded in the treatments 150 per cent NPK and 100 per cent NPK+FYM. Fertilizer was added rate of 0, 50, 100 and 150 per cent of recommended dose (100:60:40) in rice integrated with FYM at 100 per cent level and with green manure and BGA at 50 per cent level in rice. The integration with FYM showed pronounced effect on P fractions. Continuous monitoring of physical and chemical properties should be carried out for maintaining soil health and enhancing the crop production. Maximum portion of applied P was transformed in Ca-P followed by Red-P, Fe-P and Al-P. Percentage distribution of different forms of P at 0-15 cm, 15-30 cm and 30-60 cm soil depths was also studied the higher amount of all P fractions (%) were recorded in surface layer (0-15 cm) than at sub surface (15-30 cm) and low in deep layer (30-60 cm). However, higher P availability was observed at surface layer than that at sub surface layer.