Measurement and mitigation of nitrous oxide emissions from a high nitrogen input vegetable system.

The emission and mitigation of nitrous oxide (N₂O) from high nitrogen (N) vegetable systems is not well understood. Nitrification inhibitors are widely used to decrease N₂O emissions in many cropping systems. However, most N₂O flux measurements and inhibitor impacts have been made with small chambers and have not been investigated at a paddock-scale using micrometeorological techniques. We quantified N₂O fluxes over a four ha celery paddock using open-path Fourier Transform Infrared spectroscopy in conjunction with a backward Lagrangian stochastic model, in addition to using a closed chamber technique. The celery crop was grown on a sandy soil in southern Victoria, Australia. The emission of N₂O was measured following the application of chicken manure and N fertilizer with and without the application of a nitrification inhibitor 3, 4-dimethyl pyrazole phosphate (DMPP). The two techniques consistently demonstrated that DMPP application reduced N₂O emission by 37-44%, even though the N₂O fluxes measured by a micrometeorological technique were more than 10 times higher than the small chamber measurements. The results suggest that nitrification inhibitors have the potential to mitigate N₂O emission from intensive vegetable production systems, and that the national soil N₂O emission inventory assessments and modelling predictions may vary with gas measurement techniques. [ABSTRACT FROM AUTHOR]