A review of plant options for mitigating nitrous oxide emissions from pasture-based systems

In grazed pasture-based systems, urinary-nitrogen (N) voided in concentrated patches is a key source of nitrous oxide (N 2 O), a potent greenhouse gas (GHG). Development of strategies for reducing emissions from urine patches is an ongoing focus of international research. Plants can help mitigate N 2 O emissions by reducing urinary-N excretion or by lowering the N 2 O emission factor of urine. This paper reviews the current understanding of plant-effects on urinary-N 2 O emissions and confirms that plants can influence emissions. Recent New Zealand studies suggest that plantain and fodder beet show particular potential for grazed systems. A key mechanism by which plantain affects the N 2 O emission factor could be root exudates that inhibit nitrification and/or increase N immobilisation. Further studies are needed to elucidate the mechanisms involved, and to help maximise the GHG reduction potential from plant management options in pasture-based systems.