Department of Soils, Punjab Agricultural University, Ludhiana, Punjab, 141001.
A pot experiment conducted with berseem on 19 soils collected from flood-plain areas of Punjab to evaluate various P availability indices indicated that the crop responded significantly to both native and applied P. Calcium-P was the major inorganic P fraction (84.7%) followed by Al-P, Fe-P and saloid-P. Amongst different extractants for soil P, Olsen's method was found to be the most suitable. Critical P concentration in soil below which berseem responded well to P application was 10.5 mg kg−1. Both Al-P and Ca-P controlled P availability to berseem in these soils but Al-P seemed to be more important as it correlated significantly with available P extracted by most of the extractants tested and various yield and P uptake parameters.
Soil test methods, inorganic P fractions, critical P level, berseem
