Soil Tests for Available Phosphorus and their Relation with Inorganic P Fractions in Acid Soils of Karnataka

Seven extractants were tried viz., Bray No.1, Bray No. 2, Truog, Mehlich-I, Mehlich-III, Olsen and Morgan to assess the available P status of the acid soils of Karnataka. The extracted amounts of P by various extractants were correlated with inorganic P fractions. The extracting power of different extractants was in the order of Bray No. 2> Truog > Mehlich III > Bray No. I > Olsen> Mehlich I > Morgan. Simple correlation studies revealed that Bray No. I had a better correlation with saloid-P (r= 0.44**), Al-P (r = 0.56**) and Fe-P (r= 0.48**). In multiple regression analysis 63 per cent of the variation in Bray No.1 P was explained by Al-P + Fe-P.