Nitrate leaching, direct and indirect nitrous oxide fluxes from sloping cropland in the purple soil area, southwestern China

This study provides a combined dataset on N loss pathways and fluxes from sloping cropland in the purple soil area, southwestern China. A lysimeter experiment was conducted to quantify nitrate leaching (May 2004–May 2010) and N2O emission (May 2009–May 2010) losses. Nitrate leaching was the dominant N loss pathway and annual leaching fluxes ranged from 19.2 to 53.4 kg N ha−1, with significant differences between individual observation years (P < 0.05). Direct N2O emissions due to N fertilizer use were 1.72 ± 0.34 kg N ha−1 yr−1, which corresponds to an emission factor of 0.58 ± 0.12%. However, indirect N2O emissions caused by nitrate leaching and surface runoff N losses, may contribute another 0.15–0.42 kg N ha−1 yr−1. Our study shows that nitrate leaching lowered direct N2O emissions, highlighting the importance for a better understanding of the tradeoff between direct and indirect N2O emissions for the development of meaningful N2O emission strategies.

► High NO3− leaching losses lowered direct N2O emissions.
► Hydrological N losses induced un-neglected indirect N2O emissions.
► Considering both direct and indirect N2O emission is needed for reduction strategies.