Comparison of phosphate fertilisers in a grazed hill country pasture

Abstract

A grazing trial evaluated the agronomic effectiveness of 3 different types of phosphate (P) fertilisers. The same fertilisers were also evaluated in a small-plot mowing trial located within the grazing trial. In the grazing trial, which covered 35 ha of summer moist hill country, the partially acidulated phosphate rock (PAPR) and reactive phosphate rock (RPR) were as effective as superphosphate in stimulating legume and pasture production in the first year. In the second year the two slow-release materials continued to perform as well as SSP. In contrast in the mowing trial, superphosphate was more effective than RPR in the first year. This trial technique clearly underestimates the initial effectiveness of PAPR and RPR in grazed hill country. The traditional small-plot mowing trial technique, and the role of PAPR and RPR fertilisers in hill country, both need re-evaluation. Keywords hill country, superphosphate, slow release fertilisers, mowing trials, grazed pasture