The effect of sulphur fertilization on the field and chemical composition of forage oats on the Central Tablelands of NSW

Abstract

Sulphur fertilizers increased the dry matter yield of autumn-sown, high density oats (Avena sativa CV. Algerian) adequately supplied with nitrogen fertilizer, grown on previously unfertilized basaltic and granitic soils of the Central Tablelands of New South Wales. Chemical analyses showed that, under the conditions of these experiments, sulphur was insufficient for plant growth when the immature oats herbage had a sulphate S content less than 0.04 per cent, a total S content of less than 0.10 per cent, and an N : S ratio (Kjeldahl N:total S) in the range of 20 to 50. Ethanol soluble nitrogen was found to be an unsuitable index of sulphur status because of its dependence on plant nitrogen content. Gypsum was superior to elemental sulphur as a carrier during the winter period, when both were applied in a fine form (97 per cent <100 mesh), and KH2PO4 extractable soil sulphate was found to be a useful indicator of soil sulphur status.