Journal of Biological Sciences1727-30481812-5719Asian Network for Scientific Information10.3923/jbs.2007.1072.1081ur-RehmanObaid- MehdiS.M. RanjhaA.M. SarfrazM. 7200777Field studies were conducted to arrest Phosphorus requirements of wheat, sorghum fodder and rice crops at 95% relative yield; Phosphorus Fertility Buildup Factor (PFBF) and level of phosphorus buildup in a Typic Camborthid (Sultanpur series) soil of rice tract of the Punjab, Pakistan. Sorption isotherms were constructed in the laboratory and data fitted into linear form of modified Freundlich Model and doses were computed against soil solution P levels. Different theoretical P doses were applied in the field to develop soil solution P level of 0.01, 0.02, 0.03, 0.04, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.40 and 0.50 mg LG1 along with a control (native soil solution P). Phosphorus was also applied at the rate of 60 and 90 mg P2O5 kgG1 to subsequent sorghum fodder and rice crops, respectively. Wheat grain and straw, fresh sorghum fodder, rice paddy and straw yields were recorded at the harvest. Plant sampling was done at booting stage of wheat and rice and at the harvest of each crop. Soil sampling was also done at the harvest of each crop. The results indicated that maximum wheat grain yield was 4.05 mg haG1; sorghum fresh fodder yield was 43.83 mg haG1 and rice paddy yield was 4.43 mg haG1. Total P uptake by wheat, sorghum and rice was 22.73, 37.69 and 20.48 kg haG1, respectively. Mean phosphorus fertility build-up factor (mg P required to build 1 mg P kgG1 soil) was 16.23 and the level of P buildup (mg P kgG1 built-up in soil for each mg P kgG1 soil applied) was 0.062. Level of P depletion was 0.141 mg P kgG1 for NPK check plots while 0.162 mg P kgG1 for P check plots. Internal P requirement for wheat was 0.255% at booting stage and 0.281% for grain stage. For sorghum fodder, internal P requirement was 0.233% and for rice, it was 0.146% at booting stage and 0.266% for paddy stage.]]>Zulfiqar, A.M. and M. Asim,200216063Beckwith, R.S.,196555258Bhatti, M.B.,19961996pp: 1124Bigham, J.M.,1996Boschetti, A.N.G., G.C.E. Quintero and Q.R.A. Benavidez,1998229599Brar, B.S., H.S. Chhina and N.S. Dhillon,200048843844Chaudhry, E.H., A.M. Ranjha, M.A. Gill and S.M. Mehdi,20035625629Das, S.K., K.L. Sharma, B.R. Singh, B.R.C.P. Rao, K. Srinivas and M.N. Reddy,199644426433Delong, R.E., W.F. Johnson and M.D. Correll,20012001Duncan, D.B.,195511142FAO.,19841984Firat, B. and S. Gumus,20012001pp: 826-827pp: 826-827Fox, R.L. and E.J. Kamprath,197034902907Fox, R.L.,19811981pp: 223-239pp: 223-239Hanway, J.J. and R.A. Olsen,19801980pp: 681692Holford, I.,1989121520Huang, Q.N.,1998223944Iqbal, M.M., S.M. Shah, H. Nawaz and W. Muhammad,19981998pp: 161165Jones, J.P. and J.A. Benson,19756467477Ittyarial, P.J.,197917236239Jones, J.B., B. Wolf and H.A. Mills,1991Pages: 213Pages: 213Kamprath, E.J. and M.E. Watson,19801980pp: 433-469pp: 433-469Khan, G.S. and M. Rafiq,19921992pp: 245250Khan, M.S. and M.I. Makhdum,19901990pp: 451463Le Mare, P.H.,198233691707Meelu, O.P., S. Yadvinder and Y. Singh,2000453138Memon, K.S.,19821982Memon, K.S. and R.L. Fox,1983Triticum aestivium). ]]>1983Memon, K.S., H.K. Puno and R.L. Fox,1991286772Memon, K.S., A. Rashid and H.K. Puno,19921992Moodie, C.D., H.W. Smith and R.A. Mcreery,19591959Murphy, J. and J.P. Riley,1962273136Nadeem, M.Y. and M. Ibrahim,2002212123Nelson, L.E.,19801980NFDC,20032003pp: 8-9pp: 8-9Puno, H.K.,19911991Rashid, A., J. Din, N. Bughio and M. Bashir,19901990pp: 102106Rashid, M., M.I. Bajwa and R. Hussain,19921992pp: 373383Rehman, H., A. Ghani, G.A. Shah and J. Khan,19923 extractable phosphorus with yield of wheat and rice.]]>1992pp: 331344Saeed, M., Z.A. Ahmad and M.Y. Nadeem,19921992pp: 415423Sharif, M., M.S. Sarir and F. Rabi,200016587592Singh, B., Y. Singh, C.S. Khind and R.K. Gupta,2002161213Steel, R.G.D. and J.H. Torrie,19802nd Edn.,Pages: 633Pages: 633Tandon, H.L.S.,1987pp: 160pp: 160Richards, L.A.,1954Walkley, A. and I.A. Black,1934372938Watanabe, F.S. and S.R. Olsen,19653 extracts from soil.]]>29677678Webb, R.A.,197247309319