Sources of nitrous oxide from intensively managed pasture soils

High N-inputs render pasture soils prone for N2O emissions produced via multiple microbial pathways. Their contribution to N2O production remains however unknown at various scales leading to uncertainty within models simulating the N-cycle.

This soil microcosms study investigated sources of N2O in response to wetting using 15N tracing and the 15N gas flux method. Emissions of N2O via denitrification and nitrification mediated pathways showed an exponential response to soil water content across soils. Our results highlight the contribution of heterotrophic nitrification to N2O production and demonstrate the proportion of nitrified N emitted as N2O is an exponential function of soil water content.