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 N(2)O 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 N(2)O 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 N(2)O 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 N(2)O emissions, highlighting the importance for a better understanding of the tradeoff between direct and indirect N(2)O emissions for the development of meaningful N(2)O emission strategies.