Email: kirsten.verburg@csiro.au

Retaining nitrogen (N) in soils in the form of ammonia by inhibiting nitrification processes has been long hypothesised as a solution to N loss from denitrification and leaching of nitrate below the root zone. However, the findings of field experiments testing synthetic nitrification inhibitors have shown variable results.

More recently, nitrification reactions have been found to be inhibited by root exudates from some crops (e.g., bracharia, wheat, rice, sorghum, maize, canola). Research into the role of these biological nitrification inhibitors (BNIs) in reducing N loss and improving N use efficiency is currently actively being progressed. Agricultural systems modelling has demonstrated that the variable benefits of synthetic nitrification inhibitors and of controlled-release fertilisers relate to system interactions affecting the longevity of the protection of the fertiliser N, the timing of N loss events and the crop’s ability to respond to retained fertiliser N.

In this presentation we outline new research that is modelling the plausible impacts from BNI for wheat, canola and sorghum crops in Australian farming systems. Model conceptualisations will be based on a review of available experimental evidence on BNI. Systems analyses using the APSIM model will then be used to explore impacts on both productivity and emissions under different scenarios.

This work complements the ongoing international experimental research by outlining the systems aspects that may impact on benefits that can be achieved with BNI in the field. As such it can be seen as pre-experimentation modelling that informs further research and can be improved over time as more knowledge and field trial data becomes available.