No-tillage with straw mulching and re-using old film boost crop yields and mitigate soil N2O emissions in wheat-maize intercropping at arid irrigated regions

Water shortage and heavy greenhouse gas emissions are threatening agricultural sustainability with food security severely, and becoming a major issue in arid areas. It is unclear whether improved farming systems on strip-intercropping integrated with no-tillage with straw returning and re-using old film practices can be developed to reduce soil nitrous oxide (N2O) emissions and boost crop yields for tackling those issues. A four-year field experiment for wheat-maize intercropping was carried on straw residue and film management of northwestern China in 2014–2017 and aimed to comprehensively assess crop yields and soil N2O emissions. The results showed that NTSMF (no-tillage with straw mulching and re-using old film), NTSSF (no-tillage with straw standing and re-using old film), and CTSF (conventional tillage with straw incorporation and mulching new film every year) treatments increased grain yields by 15.1%, 13.7%, and 12.8% respectively, compared to CTF (conventional tillage with no straw returning and mulching new film every year, the control treatment). NTSMF, NTSSF, and CTSF treatments had greater water use efficiency by 15.7%, 13.1%, and 14.2% than CTF, respectively. On the contrary, NTSMF and NTSSF treatments had lower soil N2O emissions (NE) by 23.9% and 20.4% than CTF, and lower by 19.8% and 16.0% than CTSF, respectively. No-tillage practice used more soil moisture and produced more grain yields but emitted less N2O than conventional tillage, NTSMF and NTSSF treatments reduced soil N2O emission per volume of evapotranspiration (WUENE) by 23.6% and 20.9%, and reduced soil N2O emission intensity (NEI) by 33.9% and 30.0% in comparison to CTF. The better effect on the reduction of NE, WUENE, and SEI was found in NTSMF, and the three indicators were successively decreased by 5.3%, 4.4%, and 6.9% over NTSSF in 2016–2017. NTSMF reduced NE and boosted GY was attributed to increased synchronicity of water demand and reduced adverse effects of soil temperature variations of both intercrops’ strips. Our study concluded that grain yields were enhanced and soil N2O emissions were reduced by NTSMF treatment, and NTSMF treatment is a practical cropping production system for environmentally clean in an arid irrigated region.