Conservative strip tillage system in maize maintains high yield and mitigates GHG emissions but promotes N 2 O emissions

Optimizing N application under straw-covered strip tillage is of great significance to the rational utilization of stover resources as well as ensure food and ecosystem security, and especially N O emissions from agricultural systems. Quantifying N O emissions and even the carbon footprint (CF) from agricultural systems is crucial for future protecting agricultural production systems. A two-year field experiment was conducted on black soil in Northeast China, which set up two tillage systems: strip tillage with straw returning (ST) and conventional tillage (control: CT) without straw and three nitrogen rates: 0, farmers' practice (Nfp 240 kg hm ), and optimized nitrogen fertilizer (Nopt 180 kg hm ). We examined the characteristics of N O emissions and CF under the ST and CT systems. Among them, we indirectly calculated GHG emissions using the LCA method. Compared with CT, the ST system significantly reduces indirect GHG emissions, but did significantly increase direct cumulative N O emissions by 20.7 %, most likely because the higher soil residual nitrate nitrogen content, WFPS, and soil temperature under ST was 13.0 %, 2 % and 5.7 % higher than that under CT. Nopt treatment markedly reduced cumulative N O emissions by 36.0 %, CF , CF , and CF by 22.4 %, 23.1 %, and 23.5 % in ST, respectively, compared to Nfp. The reduction in energy use of machinery in ST results in lower fuel consumption and thus generating less CF. What's more, the decrease of CF and CF between nitrogen application treatments under ST was 5.2 % and 7.7 % higher than CT, respectively. ST system can effectively achieve higher grain yield and mitigate GHG emissions on black soil in Northeast China compared with CT, but attention should be paid to N O emissions in the soil during the maize growth period. The sustainability of balancing GHG emissions, and economic and environmental benefits can be achieved by optimizing nitrogen fertilizer manage.