Effects of triple superphosphate and Sechura phosphate rock on clover and nitrogen content of pasture

Abstract

Abstract The effect of annual applications of triple superphosphate (TSP) and Sechura phosphate rock (SPR) on clover content of permanent pasture was measured at seven sites in New Zealand. Clover content as a percentage of total pasture dry matter (DM) production (% clover) increased with phosphorus (P) application rate, and the response of % clover to P increased with time over 6 years. Most of the response occurred at P fertiliser rates up to the mean calculated maintenance rate of 25 kg P/ha per year, with little further response to twice this rate. The response in total pasture DM production to rate of P fertiliser was similar to the response in % clover. Near‐maximum % clover was achieved with Olsen P levels of 12–15. Percentage clover responses to TSP and SPR did not differ significantly at equal rates of P. There was a significant relationship between % clover and % nitrogen in total DM.