Improving and understanding the interactions between water use efficiency and nitrogen use efficiency in canola

Abstract

Key findings • The split application (4–6-leaf + bud visible) of nitrogen (N) provided several significant benefits over the single application (4–6-leaf) strategy as it: – did not significantly (P<0.05) limit yield potential across all 3 water treatments (maintained profile, 100 mm top up at flowering and starting soil water only) – provided a risk mitigation strategy by reducing upfront N costs with the option to top up N supply later in the season depending on the seasonal outlook – resulted in both greater N uptake and increased N use efficiency than the equivalent N rate as a single application across all 3 water treatments. • A higher N rate resulted in increased crop water use, however no evidence was found to support the phenomenon of ‘haying off’, i.e. the negative grain yield response to N fertiliser under late season water stress.