Dr Katherine Dunsford1, Prof. Roger Armstrong1
1Agriculture Victoria, Horsham, Australia
Biography:
Katherine is a Research Scientist with Agriculture Victoria based at Horsham. She completed her PhD in understanding the causes of poor grain yield responses to N and P Fertilisers in 2019. Her areas of research include crop nutrition, particularly N and P, as well as soil water interactions in cropping systems using APSIM and more recently amelioration of subsoil constraints using organic amendments.
Abstract:
Deep placement of Phosphorus (P) fertiliser has been shown to overcome issues of stratification, improve use efficiency and increasing yields in the Northern region, where crops are grown predominately on subsoil water. The value of subsurface P application in the southern region remains unclear, where there are major differences in the cropping systems, especially soil types and soil water dynamics. A field experiment was established on a Calcarosol in western Victoria to gain a better understanding of whether different crop species (wheat, canola and lentil) differ in their responsiveness to subsurface P application. Across the three years, all crop species showed responses to P fertiliser, in terms of both early biomass and grain yield. In 2021 and 2022, species by P treatment responses (P <0.05) were observed for wheat and canola, while results from 2023 suggested wheat and lentil were responding similarly to the P treatments (main effect of P, P<0.001). Generally, grain yields were maximised where 60 kg P/ha was applied, regardless of placement. Results suggest the temporal and spatial distribution of soil water, which allowed for P to be accessible when required during the growing season. Overall, P responses at this site were related to the amount of P applied (surface and subsurface) rather than placement per se but suggested a high residual value from deep P application on this highly alkaline soil type.