INTERACTIONS OF SULFUR, PHOSPHORUS, AND MOLYBDENUM IN RELATION TO UPTAKE AND UTILIZATION OF PHOSPHORUS BY SOYBEAN

Investigations to find out the effect of sulfur (S), phosphorus (P), and molybdenum (Mo) application on the concentration and uptake of P by soybean, cv. Bragg, were conducted at Haryana Agricultural University. In greenhouse experiments on soil deficient in S and P, S was applied at 0, 40, 80, and 120 ppm as K2SO4, and P was applied at 0, 40, and 80 ppm, as Ca(H2PO4)2. The application of S showed a synergistic effect on the concentration of P to a certain level of applied S in different plant parts of soybean. The application of P up to 80 ppm increased the P concentration significantly, but Mo application produced an antagonistic effect and significantly depressed P concentration in leaves, stems, pod husks, and grains of soybean. Total uptake of P at both sampling stages increased significantly with 40 and 80 ppm applied S and P, but application of Mo decreased P uptake at maturity. The application of S, P, and Mo affected the concentration of P in various plant parts at both stages of crop growth. The concentration of P in 45− and 110 day-old leaves gave significant positive correlation with P uptake and grain yield.