Influence of management and environment on Australian wheat: information for sustainable intensification and closing yield gaps

In the future, agriculture will need to produce more, from less land, more sustainably. But
currently, in many places, actual crop yields are below those attainable. We quantified the ability
for agricultural management to increase wheat yields across 179 Mha of potentially arable land in
Australia. Using the Agricultural Production Systems Simulator (APSIM), we simulated the
impact on wheat yield of 225 fertilization and residue management scenarios at a high spatial,
temporal, and agronomic resolution from 1900 to 2010. The influence of management and
environmental variables on wheat yield was then assessed using Spearman’s non-parametric
correlation test with bootstrapping. While residue management showed little correlation,
fertilization strongly increased wheat yield up to around 100 kg N ha−1
yr−1
. However, this effect
was highly dependent on the key environment variables of rainfall, temperature, and soil water
holding capacity. The influence of fertilization on yield was stronger in cooler, wetter climates,
and in soils with greater water holding capacity. We conclude that the effectiveness of
management intensification to increase wheat yield is highly dependent upon local climate and
soil conditions. We provide context-specific information on the yield benefits of fertilization to
support adaptive agronomic decision-making and contribute to the closure of yield gaps. We also
suggest that future assessments consider the economic and environmental sustainability of
management intensification for closing yield gaps.