There is an assumption that applying more nitrogen will immediately contribute to more nitrous oxide emissions, which is true at the outset, but it appears that is not the case when you look at the bigger picture, especially in our dryland grain cropping systems.
New research measuring the greenhouse gas emissions of various nitrogen (N) input strategies is showing that applying higher than the national average fertiliser rate can not only maximise yields but also minimise negative impacts on the environment.
The research, led by Professor James Hunt and Dr Arjun Pandey at the University of Melbourne’s Dookie Campus in central Victoria, is comparing nitrous oxide (N2O) emissions, yield and the overall greenhouse gas effect of various N decision-making systems.
These include the N bank strategy, the Yield Prophet digital decision-support tool, and N application based on national average (45 to 55kg N/ha) and zero application rates. It shows that when soil carbon storage and N crop uptake are considered along with N2O emissions, the high-input N bank approach has lower emissions intensity than the other systems tested.
Harvest results from 2023 and 2024 showed that yields were higher using N bank application rates rather than the lower national average and zero N fertiliser rates. In these years, N bank yields were also higher than those achieved using Yield Prophet.
“The idea behind the research is to assist grain growers in making more informed and less risky nitrogen decisions,” says Dr Pandey, who is using a static chamber to capture and measure N2O emissions produced by the various systems throughout the season. The research is part of a GRDC-supported RiskWi$e investment.