Effect of Phosphatic Fertilizers of Varying Water Solubilities on the Crop Yield and Physicochemical Properties of Soils

A field experiment at fixed site was conducted for three years to study the comparative efficiency of different phosphatic fertilizers on Typic Camborthids sandy loam soil of pH 8.5. Application of 60 kg P₂O₅/ha through DAP, TSP and nitrophosphate (NP) of 80 per cent WSP increased the grain yield of bajra (pearl-millet) and wheat significantly. Statistically, NP (80% WSP) was at par with DAP and TSP, but NP of 50 and 30 per cent WSP were inferior. Continued application of phosphatic fertilizers caused a decrease in soil pH and increase in organic carbon content. Available P status of soil decreased in control plots but increased from 8.0 to 26.2 kg P/ha in plots receiving 60 kg P₂O₅/ha. Fixation of added P was related to its solubility.