Further field evaluation of the controlled release nitrogen fertiliser Smartfert®

Abstract

Five field trials were conducted over 2 years in which the effects of single applications of different rates of a controlled release nitrogen (N) fertiliser, Smartfert, on pasture production and pasture N concentration were measured, relative to the same rates of SustaiN. The 2016 trials also compared multiple applications of SustaiN with a single application of Smartfert. Pasture responses to SustaiN relative to the control generally occurred within the first one to three harvests following application and then declined and became negative in the later harvests. The pasture responses to Smartfert developed more slowly and were greatest after the third harvest. In terms of total production significant (P<0.05) responses to Smartfert relative to the same rate of N applied as SustaiN occurred in three trials. SustaiN significantly increase pasture production at one site relative to Smartfert. In three trials pasture production from single applications of Smartfert applied at 100 kgN/ha were the same and in one case better (P<0.05) than three consecutive applications of 33 kg N/ha of SustaiN. The soluble N fertilisers, urea and SustaiN, elevated the mixed-pasture N concentration relative to control and to Smartfert in the first harvest following application. The nitrogen use efficiency (NUE, kg DM/ kg fertiliser N applied) of Smartfert was significantly greater (P<0.05) than for SustaiN in two trials. Keywords: fertiliser, nitrogen, nitrogen use efficiency, pasture, Smartfert, urea, SustaiN