| Abstract | Controlled release fertilisers (CRFs) are promoted as a means to optimise the productivity achieved per unit of fertiliser nitrogen (N) input and lower environmental impacts from N leaching, runoff and emission losses. Through review of experimental results, characterisation of N release patterns of commercially-available CRF products, and modelling to assess environmental, agronomic and economic benefits this project has confirmed that CRFs can play a role in Australian sugarcane systems. They can reduce N losses and provide agronomic benefits in the form of reduced N application rates and under some circumstances increased yield. The agronomic benefits are, however, highly variable from season to season. The percentage of seasons that result in measurable benefits is affected by climate, soil, crop class and timing of fertiliser application. As a consequence CRFs do not provide a consistent economic advantage over conventional fertilisers across all soil, management and climate conditions. This can be improved when the cost of environmental benefits is included or use of CRF can be targeted to those seasons where agronomic benefits are most likely. Commercially-available CRF products have different N release patterns and temperature responses. These need to be taken into account when designing fertiliser management (product choice, application and timing) in order to maximise the benefits. Development of regional decision support for growers and advisors, based on an understanding of the dynamics of local soils and cropping systems as well as seasonal climate and CRF product response to these, will be important for the successful adoption of CRFs. |
