Agricultural Research Journal

Soil phosphorus (P) fractions as affected by long-term use of inorganic and integrated fertilization under rice-wheat cropping system in loamy sand soil of Punjab, India were studied. The inorganic P fractions improved with increase in rate of P applied. The Ca-P is the dominating P fractions in these soils. The inorganic P fraction improved with fertilizer and the effect was pronounced under integrated fertilizer application. The pH and EC were negatively and significantly correlated with Sa-P, Al-P, Fe-P and Ca-P, however, the soil OC significantly and positively correlated with these fractions. The Sa-P and Al-P were major sources of Olsen^’s exchangeable soil P and were in equilibrium with Fe-P and Ca-P. The crop production (grain and straw yield) significantly improved with fertilizer. Grain yield and total P uptake by rice was positively and significantly correlated with all soil inorganic P fractions.