Return of crop residues to arable land stimulates N2O emission but mitigates NO3- leaching: a meta-analysis

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 (N2O) and leaching of nitrate (NO3-) 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 N2O emissions and NO3- leaching for different locations, climatic and soil conditions, and agricultural management strategies. On average, crop residue incorporation significantly stimulated N2O emissions by 29.7%, but decreased NO3- leaching by 14.4%. The increase in N2O 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 N2O 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 NO3- 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 N2O emissions, is particularly effective in reducing NO3- leaching in soils with loamy texture, which are generally among the most productive arable soils.

Automated summary

Incorporating crop residues into the soil is effective in sustaining soil fertility and improving soil carbon sequestration, but it can lead to increased N2O emissions and NO3- leaching. The impact of crop residue return on soil N2O emissions and NO3- leaching varies depending on soil and environmental conditions.