I work in the area of terrestrial ecosystems with a focus on agriculture, and the grazed pasture ecosystems within these. I use stable isotope science to trace and understand the transformations and fate of nitrogen and carbon in these systems. My research has a strong focus on understanding the magnitude and mitigation of nitrogen loss pathways at both fundamental and applied levels. Part of my research is applied and has investigated both agricultural management (e.g. irrigation) effects on nitrous oxide (N2O) emissions, and the efficacy of potential N2O mitigation options (e.g. manipulation of ruminant urinary constituents). I also perform fundamental research, focusing on improving our understanding of the integrated effects of soil physical, biological and chemical conditions that lead to both the production of N2O and its reduction to environmentally dinitrogen. I am applying my knowledge of nitrogen cycling processes to the aquatic sphere while looking at nitrate removal and N2O emissions from the vadose zone, streams and rivers. I am a Fellow of the New Zealand Soil Science Society, and a Fellow of the Soil Science Society of America.