Clover nutrient ratios to monitor pasture yield responses to fertiliser nutrients

Abstract

From earlier results of a limited number of trials, ratios of concentrations of phosphorus (P), sulphur (S) and potassium (K) to nitrogen (N) in white clover have been developed as indicators of nutrient adequacy. For 98% of maximum yield, clover herbage ratios of 7.4 (100 × P/N), 5.0 (100 × S/N) and 0.43 (K/N) were required. Mean critical nutrient concentrations have been reported as 0.35% P, 0.28% S and 2.05% K from earlier research on sites at an early stage of pasture development. A series of mowing trials, measuring pasture yield responses to nil or a high rate of P (120 kg/ha), S (100 kg/ha) and K (300 kg/ha) were carried out at 8 sites throughout New Zealand in 1997/98. There were significant (P