Fertiliser sulphur for North Canterbury pastures

Abstract

Natural inputs of sulphur in North Canterbury are restricted to l-2 kg of sulphur(S)/ha/year in rainfall. On the limited area of irrigated land a further 7 kg of S may be added in irrigation water. These inputs are inadequate to replace losses which occur through leaching, removal in animal products, and excretal transfer, so fertiliser S is essential to maintain farming systems. The choice of form of fertiliser varies from sulphate, to mixtures of sulphate and elemental S, to elemental S forms. Focus in this paper is on the forms which will be effective in North Canterbury, other factors which influence choice of fertilisers, and recommended fertilisers for different farming situations. Keywords: elemental sulphur, fertiliser recommendations, rate constant, sulphur oxidation, sulphur superphosphate