At Agriculture Victoria’s Horsham SmartFarm an experiment is underway to determine the extent of nitrogen losses from fertilisers in Wimmera cropping systems.
University of Melbourne PhD student Lillian Hearn is working with Agriculture Victoria’s Soil Sciences team under the supervision of Senior Soil Scientist Professor Roger Armstrong to conduct this research.
Her thesis title is, ‘Relationship between soil moisture and carbon availability on denitrification potential in dryland cropping systems of Victoria’.
Ms Hearn said 16 chambers have been set up connected to a semi-automated control system designed by Queensland University of Technology to measure nitrogen gases (N2 and N2O) emitted following fertiliser application.
‘A collection of probes measuring soil temperature, soil moisture content, redox potential and chamber air temperature are being used to complement the gas sampling and intensive soil sampling across the growing season to identify what is driving nitrogen loss.
‘The trial has a number of water treatments simulating seasons with different episodic rainfall intensities.
Ms Hearn said nitrogen fertiliser is the single biggest variable cost for dryland cropping farmers.
‘Nitrogen loss contributes to poor nitrogen use efficiency, posing major economic and environmental challenges for the grains industry.’
Within her trial plot Ms Hearn is using an isotope technique (15N) to trace how nitrogen fertiliser transforms and moves between the soil, crop and atmosphere.
Ms Hearn said one of her research hypotheses relates to another study at the Horsham SmartFarm into the residual value of nitrogen fertiliser applied to crops and how much of that nitrogen is carried over to subsequent crops, and she looks forward to seeing future results in this space.
