A short-term phosphate fertiliser advice model for grazed pasture as applied to soils in northern North Island, New Zealand

Abstract

A short-term (3–4 years) phosphate (P) fertiliser advice model for permanent pasture was developed and applied to field data obtained on highly P-sorbing soils and some low — medium P-sorbing soils in the northern North Island, New Zealand. The model demands that only results from those trials that estimate herbage yield responses to rates of P fertiliser under good rotational grazing management can be used. On highly P-sorbing soils, P status as measured by the Olsen test (to 75 mm depth) correlates positively with the Mitscherlich slope parameter, suggesting that residual P increases the availability of newly applied P. On two soil categories, it was possible to provide P requirement/ Olsen regressions that could be used to give advice on individual fields. On a very large proportion of land, however, there was insufficient field evidence to do so.

Keywords:

• phosphate
• fertiliser advice model
• pasture
• fertiliser