Dr Shihab Uddin1, Prof. Roger Armstrong2, Dr Katherine Dunsford2, Dr Nigel Wilhelm3, Dr Therese McBeath4, Dr Kirsten Verburg5, Rebecca Haling5, Dr Sean Mason6, Mr Graeme Sandral7
1NSW Department of Primary Industries, 2Agriculture Victoria Research, 3South Australian Research and Development Institute, 4CSIRO Agriculture and Food, 5CSIRO Agriculture and Food, 6Agronomy Solutions, 7Grain Research and Development Corporation
Biography:
Dr Shihab Uddin is a research scientist with NSW DPI based at Wagga Wagga. Dr Uddin’s research focuses on improving farming productivity through better nutrient management of broadacre crops. Currently, he has been investigating the effectiveness of dual placement phosphorus (P) to improve crop yield and/or P use efficiency in south-east Australian grain growing regions. Minimising the yield gap by ameliorating alkaline dispersive subsoil with various organic and inorganic amendments is another area of Dr Uddin’s research interests.
Abstract:
Phosphorus (P) stratification in soils is a common phenomenon in no-till or minimum-till systems due to the minimal mixing of near surface-applied fertilisers, the retention of stubbles and the limited vertical movement of P. Due to dry conditions in this zone, both surface-applied fertiliser P and this stratified P can be unavailable to crops. Therefore, we tested the effectiveness of deep-banded P over the current practice of applying P at or just below seeding depth.
We conducted a field trial using a combination of P rates and placement strategies. Different rates of P were either applied as a dual placement strategy (some under every seed row and some banded at approximately 20 cm below the surface in 50 cm spacings) or it was all placed under every seed row. These two strategies are described as dual P or shallow P, respectively. P was applied as MAP and balanced for nitrogen.
Our results demonstrated a significant increase in grain yield to P fertilisation, with the increases continuing to the fourth season. Dual-banded P was only beneficial with very low rates of shallow-banded P and disappeared with a higher or similar rate of shallow P. This suggests that higher rates of shallow-banded P might overcome subsoil P limitations in south-eastern Australia. Higher rates of P are also advisable to maintain a positive P balance and soil P reserves above the critical range in the long run.