SULFUR AND ZINC INTERACTIONS IN RELATION TO YIELD, UPTAKE, AND UTILIZATION OF SULFUR IN SOYBEAN

In the greenhouse at Haryana Agricultural University, we studied the effect of various sources and levels of zinc with sulfur on the yield, uptake, and utilization of sulfur. Sulfur was applied at 0, 40, 80, and 120 ppm as K2SO4, and zinc was applied at 0, 5, and 10 ppm as ZnCl2, Zn-EDTA, and Zn-Rayplex. Application of S up to 80 ppm increased dry matter and grain yield significantly. Zn-EDTA was found superior to ZnCl2 and Zn-Rayplex in increasing dry matter and grain yield of soybeans. Zinc application at 5 ppm gave the highest dry matter and grain yield. Application of 120 ppm S significantly increased total S and fertilizer S concentration in all plant parts. There was no effect of Zn sources on concentration and uptake of S. The uptake of total and fertilizer S generally increased up to 80 ppm S and 5 ppm applied Zn. The effects of S $ Zn levels and S ± Zn sources on total S uptake revealed that 80 ppm S + 5 ppm Zn and 80 ppm S with Zn-EDTA gave higher S uptake over other treatments at 45 and 110 days. Percentage of utilization of fertilizer S and S removed from soil decreased with increasing levels of S and increased with increasing levels of Zn at 45 and 110 days. More than 50 percent S had been absorbed at 45 days by the crop. At maturity (110. days) the amounts of fertilizer S retained at the 80-ppm-S level were 26.97, 17.82, 15.38, and 40.82 percent in leaves, stems, pod husks, and grain, respectively.