Agricultural management could reduce soil N2O emissions while increasing grain yields via enhancing soil moisture harvesting and improving soil nutrient status

Abstract

Intercropping can improve system productivity, but the effect of intercropping integrated with conservation tillage practices on soil N2O emissions remains unclear at the present stage. A 4-yr field experiment was performed in northwest China to examine soil moisture harvesting, soil nutrient status, and soil N2O emissions of wheat-maize intercropping with stubble residues and films management. We found that intercropping increased crop yields and reduced soil N2O emissions over monocultures. Across the intercropping treatments, NTSMFI (no-tillage with mulching stubbles and re-using residual films) and NTSSFI (no-tillage with standing stubbles and re-using residual films) boosted grain-yields by 13.8–17.1 % and 12.9–15.4 % over CTFI (conventional tillage without returning stubbles and mulching new films). NTSMFI and NTSSFI reduced soil N2O emissions by 18.4–28.7 % and 15.5–24.9 % compared to CTFI, respectively. So, NTSMFI and NTSSFI obtained a higher soil N2O emission efficiency than CTFI. The greater effect on soil N2O emissions reduction was detected in NTSMFI, and decreased by 5.1–5.4 % over NTSSFI. The main reason for NTSMFI to improve grain-yields and reduce soil N2O emissions was to enhance soil moisture harvesting and optimize the soil nutrient status. Compared to CTFI, NTSMFI increased the ratio of transpiration to evaporation by 14.4–32.0 %, improved soil organic carbon and total nitrogen concentrations, and soil C:N ratio of 0 to 60 cm soil depth by 14.1 %, 7.1 %, and 6.5 %, respectively. Adopting an environmentally clean strategy exemplified by NTSMFI was recommended as an effective technique for increasing-yields and reducing soil N2O emissions in arid irrigated regions.