Energy budgeting, carbon budgeting, and carbon footprints of straw and plastic film management for environmentally clean of wheat-maize intercropping system in northwestern China.

Modern agricultural production is an energy- and carbon-intensive system. Enhancing energy and carbon efficiencies and reducing carbon footprints are important issues of sustainable development in modern agriculture. This study aimed to comprehensively assess energy and carbon budgeting and carbon footprints in wheat-maize intercropping, monoculture maize, and monoculture wheat with straw and plastic film management approaches, as based on a field experiment conducted in northwestern China. The results showed that intercropping had a greater grain yield by 12.8% and 131.0% than monoculture maize and wheat, respectively. Intercropping decreased energy and carbon inputs, increased energy and carbon outputs, thus improving energy and carbon efficiency, compared to monoculture maize. Intercropping reduced carbon footprint (CF) and yield-scale on the carbon footprint (CFy) via decreasing soil CO2 equivalent emissions over monoculture maize. For the intercropping treatments, NTSMw/NTm (no-tillage with straw mulching and residual plastic film re-mulching) and NTSSw/NTm (no-tillage with straw standing and residual plastic film re-mulching) treatments increased grain yields by 14.9% and 13.8% over CTw/CTm (conventional tillage with no straw returning and annual new plastic film mulching). The lower energy inputs and higher energy outputs were observed in NTSMw/NTm and NTSSw/NTm treatments, thus, NTSMw/NTm and NTSSw/NTm had greater energy use efficiency by 36.9% and 34.9% than CTw/CTm. NTSMw/NTm and NTSSw/NTm treatments decreased carbon inputs and increased carbon outputs, thus improving carbon efficiency by 56.6% and 53.1%, compared to CTw/CTm. NTSMw/NTm and NTSSw/NTm treatments decreased CF by 16.8% and 14.3%, and decreased CFy by 27.6% and 24.8% compared to CTw/CTm, respectively, because of the decrease in soil CO2 equivalent emissions. Our study indicated that system productivity, as well as energy and carbon efficiencies were enhanced, and carbon footprints were reduced by NTSMw/NTm and NTSSw/NTm treatments, and NTSMw/NTm had a more robust effect, indicating this treatment is the most sustainable cropping system in arid areas.