Summary of eleven long-term field trials with 'Longlife' phosphatic fertiliser

Abstract

Longlife' phosphatic fertiliser is manufactured in New Zealand by mixing reactive phosphate rock (RPR) with single superphosphate (SSP) when the SSP is at an ex-den stage. Commercially produced Longlife (70:30 SSP:RPR) was evaluated in 6 field mowing trials in the North Island over 3 or4 years. Also, a 5050 (SSP:RPR) Longlife-type product was examined in 5 field trials throughout New Zealand over 5 or 6 years. Longlife was compared against SSP and/or triple superphosphate (TSP) in all trials, and RPR treatments were included in 7 trials. In all trials with commercially produced Longlife, the pasture response to Longlife tended to be less than that to SSP or TSP in the first 2 years and was significantly different (P 6.0 and/or rainfall ~800 mm/year). Keywords field trials, Longlife, phosphate, reactive phosphate rock, superphosphate