Strategies to help with nitrogen decisions

WHY THIS PROJECT WAS NEEDED

Grain growers often find it difficult to match nitrogen supply to crop nitrogen demand. This is because estimating nitrogen supply is based on nitrogen demand, which has a high level of uncertainty because of the high error associated with predicting August to October rainfall.  

A new approach seeks to reduce uncertainty of nitrogen supply to the crop. This approach is referred to as ‘N banking’ and  works to maintain a specified or pre-determined soil mineral nitrogen level that is topped up each winter to the target N bank level, ignoring the crop nitrogen demand outlook. In the N banking strategy, the crop draws upon the nitrogen bank and, together with extra mineralisation in high rainfall years, this approach ensures high nitrogen demand years are matched with adequate nitrogen supply.  

In short: This project is comparing nitrogen strategies in south-east NSW to optimise nitrogen management in crop production. Trial data will inform economic analysis, aiding farmers to adopt more efficient nitrogen use practices.

Project focus

This project aimed to compare nitrogen-based demand and nitrogen-banking strategies to aid nitrogen decision making in south-east New South Wales and simplify the approach to nitrogen management in cereal and canola growing regions.

In partnership with FarmLink and other farming systems groups, Riverine Plains established a replicated trial site near Wagga Wagga (NSW). The trial compared ‘N banking’ and ‘N demand’ based strategies for closing the nitrogen limited yield gap with nil and national average control treatments. Results from the trial will be used to complete an economic analysis of scenarios for ‘N banking’ and ‘N demand’ based strategies compared to controls. The project includes current grower practice as the baseline treatment.

The trial results were presented to farmer groups in south-eastern NSW on the attributes of both ‘N banking’ and ‘N demand’ based strategies.