Pasture yield responses to sulphur fertilisers in relation to nutrient ratios in white clover

Abstract

differences in the proportion of S° oxidised 30 months after application between treatments. In the first two years, clover S/P ratios were above the optimum range for balanced nutrition (0.7-0.8) for all fertilisers except 15SS, TSP, TSP/S, DAP/S, and RPR/S. Triple superphosphate, 15SS, and 22SS had clover S/P below the optimum range in the third year. Clover 100 S/N ratios for 33SS, 36SS, and 50SS were in the optimum range (4.8-5.0 for 95-98% RY) for most of the trial and increased into that range for SSP, TSP/S, DAP/S, and RPR/S by the end of the third year. Most other treatments had clover S/N ratios below the optimum range. In this Southland environment there was no pasture yield response from applying extra S° over and above an average of 22 kg sulphate S ha-1 yr-1 (SSP). A lower average rate of 5 kg sulphate S ha-1 yr-1 plus 15 kg S° ha-1 yr-1 (TSP/S, RPR/S), resulted in a reduction in pasture yield compared with SSP. To achieve similar pasture yield to SSP over three years, an initial application of at least 33 kg sulphate S ha-1 and 77 kg S° ha-1 (33SS) was required.

Liveweight gains of lambs from Caucasian clover/ryegrass and white clover/ryegrass swards on soils of high and low fertility

“…These lamb performance and sward responses to higher soil fertility were within the range expected for sedimentary soils on lowland farms in New Zealand (Sinclair et al. , 1997; Morton et al. , 1998, 1999).…”