The role of sulphur in maintaining lucerne yields in the Lockyer Valley

Abstract

Results of a long-term field experiment at Gatton in the Lockyer Valley of south-eastern Queensland showed that sulphur fertilizer was necessary for the maintenance of high production in irrigated lucerne stands. A single application of 125 kg S ha-1 was effective in maintaining vigorous growth of lucerne for five years, and an application of 250 kg S ha-1 maintained stand vigour for nine years. No advantage of smaller more frequent applications was demonstrated. Flowers of sulphur, gypsum and superphosphate were equally effective as sulphur carriers. In addition to maintaining stand vigour and reducing weed invasion, application of sulphur raised both the sulphur and the nitrogen content of forage. However relationships between yield and sulphur content, and yield and N : S ratio in the forage were too variable from harvest to harvest to permit precise detection of sulphur deficiency by means of plant analysis.