Clemens Scheer(A,D), David W. Rowlings(A), Massimiliano De Antoni Migliorati(A),
David W. Lester(B), Mike J. Bell(C), and Peter R. Grace(A)
A. Institute for Future Environments, Queensland University of Technology, Brisbane, Qld 4000, Australia.
B. Queensland Department of Agriculture and Fisheries, PO Box 2282, Toowoomba, Qld 4350, Australia.
C. Queensland Alliance for Agriculture and Food Innovation, School of Crop and Food Sciences,
University of Queensland, Gatton, Qld 4343, Australia.
D. Corresponding author. Email: [email protected]
To meet the global food demand in the coming decades, crop yields per unit area must increase.
This can only be achieved by a further intensification of existing cropping systems and will require even higher inputs of N fertilizers, which may result in increased losses of nitrous oxide (N2O) from cropped soils.
Enhanced efficiency fertilizers (EEFs) have been promoted as a potential strategy to mitigate N2O emissions and improve nitrogen use efficiency (NUE) in cereal cropping systems.
However, only limited data are currently available on the use of different EEF products in sub-tropical cereal systems.
A field experiment was conducted to investigate the effect of three different EEFs on N2O emissions, NUE, and yield in a sub-tropical summer cereal cropping system in Australia.
Over an entire year soil, N2O fluxes were monitored continuously (3 h sampling frequency) with a fully automated measuring system.
The experimental site was fertilized with
different nitrogen (N) fertilizers applied at 170 kg Nha–1, namely conventional urea (Urea), urea with the nitrification inhibitor 3,4-dimethyl pyrazole phosphate (DMPP), polymer-coated urea (PCU), and urea with the nitrification inhibitor nitrapyrin (Nitrapyrin).
Nitrous oxide emissions were highly episodic and mainly controlled by heavy rainfall events within two months of planting and fertilizer N application.
Annual N2O emissions in the four treatments amounted to 2.31, 0.40, 0.69, and 1.58 kgN2O-N ha–1 year–1 for Urea, DMPP, PCU, and Nitrapyrin treatments, respectively, while unfertilized plots produced an average of 0.16 kgN2O-N ha–1 year–1.
Two of the tested products (DMPP and PCU) were found to be highly effective, decreasing annual N2O losses by 83% and 70%, respectively, but did not affect yield or NUE.
This study shows that EEFs have a high potential to decrease N2O emissions from sub-tropical cereal cropping systems.
More research is needed to assess if the increased costs of EEFs can be compensated by lower fertilizer application rates and/or yield increases.
Received 10 November 2015, accepted 29 February 2016, published online 6 July 2016