Mixed results on grain yield responses to deep-placement of P in southern Queensland

Abstract

Deep-placement (0.2 m) of phosphorus (P) for grain crops has produced a range of outcomes across 11 locations and 24 site years in southern Queensland. Some locations have provided substantial increases in yield over several seasons, but others fail to respond. Both summer and winter cereals appear more consistent in responding to deep P than winter pulses. There were too few summer pulses to make any conclusions about their responsiveness. Experiments used either triple superphosphate or mono-ammonium phosphate as a P source, with indications that fertiliser form may influence P response.