Evaluation of emission factors for indirect N₂O emission due to nitrogen leaching in agro‐ecosystems

Abstract

We reviewed the available data of NO 3 − and dissolved N 2 O concentration in leached water in agro‐ecosystems from 11 published papers and four unpublished studies, to reevaluate the IPCC default emission factor (N 2 O‐N/NO 3 − ‐N) for indirect N 2 O emission in agro‐ecosystems. The emission factor was estimated to be 0.0024, indicating that the IPCC's present emission factor (0.015) and estimate of indirect N 2 O emission are too high. Using the estimated value of 0.0024 as the emission factor revises the global indirect N 2 O emission from N leaching and runoff in agro‐ecosystems downward from 1.6 to 0.80 Tg N y −1 and the sum of direct and indirect global N 2 O emission due to agriculture from 6.3 to 5.5 Tg N y −1 .