Phosphate rocks and phosphate rock/sulphur granules as fertilisers for hill country pasture

Abstract

Abstract Reactive phosphate rocks (PR) from North Carolina and Peru (Sechura), applied either as granules or after co-granulation with elemental sulphur (PR/S), were evaluated as phosphate fertilisers on a north-facing slope of a hill country pasture. Single superphosphate was used as the standard fertiliser. The fertilisers were applied annually for 3 years at rates of 15, 25, 35, and 70 kg P ha-1 and the residual effects were monitored for one year (at which time none of the phosphate fertilisers was reapplied) and for a further 6 months when superphosphate alone was reapplied. The soil was a yellow-brown earth and brown granular loam intergrade limed to pH 5.8. Pasture dry matter yield and P uptake were extremely variable in the first year. In both year 2 and year 3 pasture growth increased with the rate of fertiliser P application but there was no significant difference between fertiliser P forms. Uptake of P by pasture followed a similar pattern. All fertilisers had similar residual effects on pastur...