The paper “Incubation experiments using nitrogen isotope discrimination to estimate ammonia emission from amended sheep manure treatments“, published in The Journal of Agricultural Science, has been chosen as the latest Editorial Highlight and is freely available to download for one month.

Ammonia (NH₃) emissions from livestock manure pose significant environmental challenges, prompting the need for effective mitigation strategies. Addressing this concern, two pioneering 10-day in vitro experiments were conducted to explore the correlation between nitrogen (N) isotope discrimination (δ¹⁵N) and NH₃ emissions from sheep manure. The findings not only shed light on the dynamics of NH₃ emissions but also offer promising avenues for estimating and mitigating these emissions in agricultural settings.

In the first experiment, three distinct manure mixtures were examined: a control group (C), C mixed with lignite (C+L), and grape marc (GM). Remarkably, the addition of lignite in C+L resulted in a substantial reduction of cumulative manure-N loss by 81% and 68% compared to the C and GM groups, respectively. Moreover, the cumulative emitted manure NH₃-N was significantly lower in the C+L group than in the other groups, highlighting the efficacy of lignite application in mitigating NH₃ emissions from sheep manure. In the second experiment, different urine-faeces mixtures with varying ratios were studied, revealing intriguing insights into NH₃ emission dynamics. Notably, higher NH₃ emissions were observed in mixtures with higher urine content, indicating the influence of urine-to-faeces ratio on NH₃ emissions. These findings underscore the importance of considering manure properties, including N content and composition, in devising effective NH₃ mitigation strategies.

Furthermore, both experiments unveiled a non-linear positive relationship between δ¹⁵N of manure and NH₃ emissions, except for manure treated with lignite. This observation aligns with previous studies and emphasizes the potential of δ¹⁵N and Δ¹⁵N as valuable biomarkers for estimating NH₃ emissions from sheep manure. Leveraging these biomarkers could facilitate more accurate and efficient estimation of NH₃ emissions, enabling targeted mitigation efforts to enhance environmental sustainability in agriculture.

The innovative incubation experiments provide valuable insights into the complex relationship between manure properties, δ¹⁵N, and NH₃ emissions. The demonstrated efficacy of lignite application and dietary modifications, such as incorporating grape marc, underscores the potential of these strategies in reducing NH₃ emissions from sheep farming operations. Moving forward, further research and field trials are warranted to validate these findings and translate them into practical mitigation strategies for mitigating NH₃ emissions and promoting sustainable agricultural practices.

Dr. Hassan Khanaki extends sincere appreciation to the University of Melbourne for financial support. Thanks are extended to my team members, Dr. Paul (Long) Cheng, Prof. Richard Dewhurst, Prof. Brian Leury, Prof. Deli Chen, and Mrs. Yumeng Song for their invaluable collaboration and expertise, which have greatly enriched the outcomes of this endeavor.

The Journal of Agricultural Science Editorial Highlights are selected by the Editor-in-Chief and are freely available for one month. View the recent selections here.