Guangdi D. Li1, Adam J. Lowrie1, Richard J. Lowrie1, Graeme D. Schwenke2, Richard C. Hayes1 and Hongtao Xing1,3
1 NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, PMB, Pine Gully Road, Wagga Wagga, NSW 2650, Australia. www.dpi.nsw.gov.au, email@example.com
2 NSW Department of Primary Industries, Tamworth Agricultural Institute, 4 Marsden Park Road, Tamworth, NSW 2340, Australia
3 School of Life Sciences, Faculty of Science, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia
Nitrogen inhibitors have been used to reduce nitrous oxide (N2O) emission and increase nitrogen use efficiency in many agricultural systems. However, its agronomic benefits, such as the improvement of grain yield, is uncertain. A four-year experiment with a wheat–canola–pulse–wheat crop sequence was established at Wagga Wagga, NSW in 2012. Nitrification inhibitor (3,4-dimethylpyrazole phosphate, DMPP) and urease inhibitor [N-(n-butyl) thiophosphoric triamide, NBPT] were applied as coated urea products (ENTEC and Green Urea, respectively) to wheat and canola crops over two growing seasons in 2012 and 2013. The objectives were a) to investigate whether the use of ENTEC and Green Urea can reduce N2O emissions and increase grain yield; and b) to conduct a gross margin analysis to assess the economic benefit by using ENTEC and Green Urea. Results showed that DMPP reduced N2O emission by 34% on the wheat crop in 2012 and 62% on the canola crop in 2013. There were no yield benefits from either ENTEC or Green Urea in any season. As a result, there was no economic benefit to use N inhibitors in dryland cropping system in southern NSW due to their higher input cost.