Initial and medium-term responses of white clover to three sulfur fertilizers on a basaltic soil

Abstract

The short and medium-term effects of three sulfur fertilizers on white clover pasture were measured on a sulfur-deficient basaltic soil in the Northern Tablelands of New South Wales between 1976 and 1979. The treatments were a single application of elemental sulfur, gypsum, and sulfur-fortified superphosphate (SF45) at 0, 20, 40, and 80 kg S/ha and three annual applications of elemental sulfur and gypsum at 0, 10, 20 and 30 kg S/ha. Gypsum and SF45 gave the largest effects in the first year, and elemental sulfur and SF45 caused the largest residual effects in the third year. A single application of 20 kg S/ha gave near maximum yields over the three year period provided that most of the sulfur was supplied in the elemental form. However, to achieve maximum yields in the first year about 20% of the sulfur was required as sulfate. Likewise maximum yields in the third year required a fresh application of 10 sulfate S/ha. The relatively large residual effect of gypsum was attributed to the slow-leaching soil, and the resistance of the coarse textured elemental sulfur (65% >0.5mm) to leaching by the high summer rainfall.