Forms of phosphorus and its bioavailability in rice grown in an alluvial soil treated with rock phosphate enriched compost

Lower utilization efficiency of phosphorus (P) in soils is a major setback for the agricultural sector. The objective of this study was to investigate the effect of compost enriched with Rock phosphate on fractions of P in soil and how these forms affect the bioavailability of P in Rice. P fertilization was performed with the enriched compost and compared with rock phosphate and a conventional P fertilizer i.e. single superphosphate (SSP). We conducted a field experiment at Bihar Agricultural University, Sabour with Rice as the test crop in a randomized block design. Chemical P fractions were estimated through sequential fractionation and biomass production and P concentrations in plant parts were measured to estimate the plant P uptake. Yield, yield attributing parameters and P uptake in straw and grain were observed to be affected significantly by the addition of P enriched compost along with 50% recommended dose for P with the total recommended dose for N and K, when compared to absolute control. The alkaline nature of experimental soil seemingly improves the solubility of P from various fractions and the use efficiency of rice, which favors P uptake which was evidently the factors that contributed to these results. The percentage contributions of different fractions to the total P content in soil after paddy harvest were observed to be in the order: Labile-P < Fe/Al-P < Ca-P < residual P. Combined application of P enriched compost and inorganics sustained crop yield and enhanced P uptake in Rice when compared with sole application of chemical fertilizers.