The diagnosis and correction of sulfur deficiency and the management of sulfur requirements in New Zealand pastures: a review

This review consolidates and updates our understanding of the diagnosis and correction of soil S deficiencies, and the management of S requirements for pastures, using both historical data from field trials and recent developments in the understanding of the sulfur (S) cycle in New Zealand pastoral soils. The basis for, and the practical implications of, a new quasi-equilibrium S model for pastures is discussed in terms of the size and changes in the pools of sulfate S, readily available extractable organic S (EOS) and total organic S over time and with the addition and removal of S through fertiliser and leaching. With this background, the use and interpretation of the 2 S soil tests are discussed. Historical data from field trials and the recent research on nutrient ratios are used to update the use of pasture S concentrations for diagnosing S deficiency. Historical data is also used to examine the distribution and size of pasture responses to S fertiliser and to define the biological S requirements for New Zealand soils. The effects of time, single or split, and annual or triennial applications of sulfate and S-0 are reviewed and the suitability of current S-0 fertilisers is discussed. Generalised fertiliser S strategies are then developed for the major soil groups, climate zones and farm types, based on all this information.