The effectiveness of several fertilizers in supplying sulfur to temperate pastures

Abstract

Pastures on two contrasting soils, one a heavy-textured soil derived from basalt and the other, a light-textured soil from dacite, were treated with several sulfur fertilizers at a single rate of sulfur application (20 kg/ha). The fertilizers ranged from ammonium and calcium sulfates to forms of elemental sulfur, with a composite form (sulfur-fortified superphosphate) included. The dry-matter yield and sulfur concentration of the pasture were measured over three or four years, and the net recovery of sulfur from the various fertilizers was calculated. The most soluble source, sulfate of ammonia, was the most effective source of sulfur to the pasture on the heavy-textured soil, followed by the less soluble gypsum but this order was reversed on the light-textured soil, which may have lost sulfate by leaching. The two forms of elemental sulfur (prilled Agri-Sul and granular Foam S) were much less effective at both sites and sulfur-fortified superphosphate was of intermediate effectiveness. However, the effectiveness of the elemental forms was better sustained into the third year, indicating that less frequent application of such forms would be feasible, provided that much heavier initial rates were used.