Utilisation by white clover and ryegrass of sulphur from 35s‐Labelled Gypsum

Abstract

Abstract This investigation reports the uptake of S from a surface application of 35S‐labelled gypsum by a ryegrass‐white clover mixture sward and by a pure ryegrass stand, each growing at three levels of N in the field. Nitrogen stimulated ryegrass growth, reducing the contribution of white clover to the total yield, whereas S did not influence the yield of either species. Gypsum, while not increasing the total S in the white clover, contributed 23 to 50% of the total S concentration. In contrast, gypsum increased the total S in the ryegrass. The level of N nutrition did not alter the fertiliser S in white clover, but depressed the total S in the ryegrass. Nitrogen enhanced the fertiliser S in ryegrass at the first harvest, however, at the second harvest N depressed the fertiliser S. Recovery of applied S was increased by N, reaching a maximum value of 19.8% by two harvest, and was decreased with increasing rate of gypsum. Without ‐N the white clover accounted for 50% and 27% of the S recovery by the mix...