Baobao Pan1, Shu Kee Lam1, Arvin Mosier1, Yiqi Luo2, Deli Chen1
1 Crop and Soil Science Section, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, VIC 3010, Australia, Email: bpan@student.unimelb.edu.au
2 Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
Ammonia (NH3) volatilization is a significant pathway of nitrogen (N) loss from cropping systems. A number of studies have investigated the effects of management practices on NH3 emission, but the findings are sometimes contradictory or inconclusive. A meta-analysis was conducted to quantitatively synthesise the global literature on the strategies for mitigating NH3 emission from agricultural systems. Unlike qualitative reviews, a meta-analysis combines results from different studies to identify patterns among study results. The mitigation strategies included in our meta-analysis were: irrigation, N application method (deep placement), fertilizer type (ammonium-based vs. urea) and the use of urease inhibitors and controlled release fertilizers. Irrigation after fertilization and deep placement of N fertilizers decreased NH3 emission by around 35% and 55%, respectively. Ammonium-based fertilizers decreased NH3 loss by 31-75% when compared to urea. Both urease inhibitors and controlled release fertilisers effectively decreased NH3 volatilization by 54-68%. The findings provide critical information on how to minimize NH3 volatilization and increase N use efficiency and productivity in cropping systems.