Mr.Adil,If you could access,the following paper may be consulted for evaluating the residual value and recovery of P.
Residual effects of phosphorus applied to soybean or wheat in soybean-wheat cropping system on a Typic Haplustert .By Subba Rao,A .et al. J.Agric.Sci.(U.K).127(3),325-330.