Do Western Australian grain growers risk decreasing the nitrogen use efficiency of their soil when they apply sulphate of ammonia fertiliser in close succession with lime?

This is the burning question researchers from The University of Western Australia and Murdoch University aim to answer through a new Grains Research and Development Corporation project.

Led by the UWA School of Agriculture and Environment Associate Professor Louise Barton, the research team includes UWA scientists Professor Zed Rengel, Dr Fiona Dempster, Paul Damon and Associate Professor Matthias Leopold, as well as Murdoch University Professor Daniel Murphy.

Image: Research Officer Paul Damon and Associate Professor Louise Barton in a UWA glasshouse.

Associate Professor Barton said WA grain growers wanted to improve their understanding of the interactions between sulphate of ammonia and lime.

"The results of this study will directly respond to growing concerns that applying sulphate of ammonia to soil recently top-dressed with lime may promote loss of nitrogen gases and decrease nitrogen use efficiency," Associate Professor Barton said.

"We will determine the possible impacts such as increased gaseous nitrogen losses, reduced crop productivity and nitrogen use efficiency, and communicate this with growers."

Associate Professor Louise Barton

The project will provide new and quantitative data for WA growers to help with their decisions regarding the use of nitrogen fertilisers. The collaborative project will be carried out in two phases over 13 months.

In the first stage, the research team will complete a scientific review and agricultural consultant survey to compile the latest information about the impact of sulphate of ammonia and lime on nitrogen gases and crop yield and the extent to which this may be occurring in WA grain growing regions.

Secondly, a series of glasshouse studies will investigate the short and medium-term interactions between soil type, liming, and application of sulphate of ammonia on gaseous nitrogen losses, crop growth and grain yield.

The multidisciplinary team includes members of the SoilsWest alliance, The UWA Institute of Agriculture and UWA Centre for Agricultural Economics and Development.

The researchers will apply many decades’ worth of knowledge, skills, and technical and regional experience to the project.

“A key strength is our combined experience in the design and delivery of field and glasshouse studies focussing on soil nitrogen cycling, nitrogen fertility and management of grains,” Associate Professor Barton said.

“Additionally, members of our team have the proven ability to conduct industry surveys, more than 25 years’ experience measuring soil gaseous nitrogen emissions and extensive knowledge of WA cropping soils.”