Effects of foliar-applied sulphur and nitrogen on grain growth, grain sulphur and nitrogen concentrations and yield of winter wheat

Elemental sulphur (32 kg S/ha) and urea (30 kg N/ha) were applied to the foliage of different winter wheat cultivars, half at flag leaf emergence and half at ear emergence, in factorial experiments in 1986, 1987 and 1988. There were no clear visual symptoms of S deficiency, but there was evidence from soil analysis, grain S concentration and grain N:S ratio that the crops were marginally deficient in sulphur. Disease severity was generally negligible. Leaf senescence at the end of grain growth was delayed by sulphur in two of the three years, both with and without urea in 1987, but only with urea in 1988. Sulphur, both alone and mixed with urea, increased grain S concentration from early grain growth in 1986 and 1987, but not until the end of grain growth in 1988. Urea alone reduced yield in 1986 and 1987, but mixing S with the urea compensated for this phytotoxic effect. Yield was not significantly increased by S when compared with plots receiving neither urea nor S.