EFFECT OF SULFUR ADDITIONS ON THE YIELD AND ELEMENTAL COMPOSITION OF RED-CLOVER AND RYEGRASS

Experiments were conducted in a growth chamber using three soils testing low in extractable sulfate (SO4), and two crops, red clover (Trifolium pratense L.) and annual ryegrass (Lolium multiflorum L.). The study's objectives were to determine how the three soils compared in plant available sulfur (S) and to test the effects of various rates of potassium sulfate (K2SO4) and gypsum on the elemental composition, nitrogen:sulfur (N:S) ratio, and dry matter yield of two cuts of forage taken from each of the two crops. Of the three soils used, the Queens sandy loam tested lowest in extractable S and the plants grown in this soil were lowest in tissue S and S uptake. There was no yield response to S amenments except for the second cut of ryegrass grown in the Queens soil. In terms of S uptake and the N:S ratio of the forage, ryegrass was more responsive than red clover to S amendments from either source. Gypsum was as effective as K2SO4 for supplying plant avallable S.