Return of crop residues to arable land stimulates N2O emission but mitigates NO3− leaching: a meta-analysis
Zhijie Li, Rüdiger Reichel, Zhenfeng Xu, Harry Vereecken, Nicolas Brüggemann
Abstract
Abstract Incorporation of crop residues into the soil has been widely recommended as an effective method to sustain soil fertility and improve soil carbon sequestration in arable lands. However, it may lead to an increase in the emission of nitrous oxide (N 2 O) and leaching of nitrate (NO 3 − ) to groundwater due to higher nitrogen (N) availability after crop residue incorporation. Here, we conducted a meta-analysis based on 345 observations from 90 peer-reviewed studies to evaluate the effects of crop residue return on soil N 2 O emissions and NO 3 − leaching for different locations, climatic and soil conditions, and agricultural management strategies. On average, crop residue incorporation significantly stimulated N 2 O emissions by 29.7%, but decreased NO 3 − leaching by 14.4%. The increase in N 2 O emissions was negatively and significantly correlated with mean annual temperature and mean annual precipitation, and with the most significant changes occurring in the temperate climate zone. Crop residues stimulated N 2 O emission mainly in soils with pH ranging between 5.5 and 6.5, or above 7.5 in soils with low clay content. In addition, crop residue application decreased NO 3 − leaching significantly in soils with sandy loam, silty clay loam, and silt loam textures. Our analysis reveals that an appropriate crop residue management adapted to the site-specific soil and environmental conditions is critical for increasing soil organic carbon stocks and decreasing nitrogen losses. The most important novel finding is that residue return, despite stimulation of N 2 O emissions, is particularly effective in reducing NO 3 − leaching in soils with loamy texture, which are generally among the most productive arable soils.