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

Abstract

We reviewed the available data of NO3- and dissolved N2O concentration in leached water in agro-ecosystems from 11 published papers and four unpublished studies, to reevaluate the IPCC default emission factor (N2O-N/NO3--N) for indirect N2O emission in agro-ecosystems.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 N2O emission are too high. Using the estimated value of 0.0024 as the emission factor revises the global indirect N2O emission from N leaching and runoff in agroecosystems downward from 1.6 to 0.80 Tg N y-1 and the sum of direct and indirect global N2O emission due to agriculture from 6.3 to 5.5 Tg N y-1. Copyright 2005 by the American Geophysical Union.