Evaluation of phosphorus efficiency in soybean (Glycine max) and wheat (Triticum aestivum) cropping system in relation to fertilizer on a Typic Haplustert

In a field experiment in a semi-arid climate on a Typic Haplustert, several means of measuring phosphorus efficiency were evaluated in soybean [Glycine max (L.) Merr.]-wheat (Triticum aestivum L. emend. Fiori & Paol.) cropping system in relation to applied P. Seven rates of P (0, 10, 20, 40, 60, 80 and 100 kg P/ha) were applied to both the crops. The computed optimum fertilizer P rates to achieve 90% of the maximum yield were 32.5 to 33.5 kg P/ha for soybean and 49.5 to 44.5 kg P/ha for wheat during the 2 years. More applied P was translocated to grain in wheat tan in soybean. The efficiency of fertilizer - utilization in both the crops was reduced beyond 40 kg P/ha. Wheat proved more efficient in utilizing the fertilizer P and also required larger dose of fertilizer P, whereas soybean efficiently utilized the soil P and required lower rate of the fertilizer P.