Inorganic soil phosphate fractions as related to soil-test values by common methods

Summary An attempt to find the relationship among the soil inorganic phosphate fractions and the soil test values determined with various common methods, has been made in the present studies. Out of the methods tried (Olsenet al., Bray and Kurtz, Datta and Kamath, Bingham) the soil-test values obtained with only Bray and Kurtz's method no. 2 have shown a positive significant relationship with Ca-P fraction while the others have shown more or less a positive significant correlation with saloid-bound P, Al-P and Fe-P fractions. Negative significant relationships of Al-P and Fe-P with Ca-P indicate that they increase or decrease at the expense of each other by fertilisation and cropping. Application of basic slag at the rate of 120 lbs P₂O₅ per acre indicate a maximum increase in most of the soil test values and the saloid bound P and Al-P fractions suggesting probably its high residual value in the soils. The use of the method of Datta and Kamath along with that of Olsenet al. and Bray and Kurtz no. 1 has been recommended.