Correlation of Available Phosphorus Values Obtained by Different Methods to Phosphorus Uptake by Paddy

The coefficient of correlations were worked out between available phosphorus obtained with five different methods, viz., water (Bingham), 0.5M NaHCO₃ at pH 8.5 (Olsen), 0.03M NH₄F plus 0.025N HCl (Bray-1), 0.03M NH₄F plus 0.1N HCl (Bray-2) and 0.002N H₂SO₄(Troug), and phosphorus uptake and dry matter yield of paddy I.R.8 grown on some Bundelkhand soils. Olsen's method using 0.5M NaHCO₃ appeared to be more reliable than other methods. The significant positive correlations between Olsen's available P and P-uptake and Olsen's available P and dry matter yield were 0.758 and 0.731 respectively. Saloid-P and Ca-P fractions were significantly correlated with P-uptake in alkaline calcareous soils and correlation coefficients were 0.801 and 0.556 respectively.