Abstract:

Post-wheat green manuring is a key practice for reducing synthetic fertilizer use and enhancing soil fertility. However, its impact on nitrous oxide (N 2 O) emissions is variable, necessitating integrated strategies for effective mitigation. Based on a 15-year field experiment and an incubation experiment, this study evaluated how incorporating attapulgite clay into a high-efficiency green manuring system with 30% chemical fertilizer reduction (G+F 70 ) affects N 2 O emissions. Compared with conventional fertilization (F 100 ), the G+F 70 system increased wheat yield by 9.4% on average and improved soil quality index by 184.5%. This improvement was attributed to enhancements in soil organic matter, total nitrogen, mineral nitrogen, dissolved organic nitrogen, microbial biomass carbon, available potassium and enzyme activities. Relative to G+F 70 alone, the incorporation of attapulgite reduced accumulated N 2 O emissions by 23.4% (field) and 13.3% (incubation), lowered the N 2 O emission factor and yield-scaled N 2 O emission intensity by 41.5% and 26.2%. Attapulgite reduced soil ammonium content, nitrification potential (NP), and the (narG + nirK )/ nosZ ratio, while increasing nosZ gene abundance. Random forest analysis identified nosZ as a primary predictor of N 2 O emissions, with NP and denitrification potential (DNP) also contributing. Partial least squares path showed NP positively correlated with N 2 O emissions and nosZ negatively correlated, whereas DNP had no direct effect, inconsistent with its contribution in random forest. Therefore, both DNP and denitrification completeness should be considered for N 2 O mitigation. In conclusion, integrating attapulgite into the post-wheat green manuring system with reduced fertilizer sustains yield and soil fertility while effectively mitigating N 2 O emissions by modulating key microbial nitrogen transformation processes.