Re-used mulching of plastic film is more profitable and environmentally friendly than new mulching

Reducing the usage and residue of plastic mulch film, but not productivity, is crucial for the sustainable development of dryland farming. The re-used mulching of plastic film (directly cropping on the already used plastic film) was tested compared to no-mulch and new mulching (mulching new film each year), in the grain maize, forage maize, and faba bean cropping systems. The new mulch significantly increased topsoil temperature (18.4% above average), upper 2 m soil moisture (20.2%), crop yield (85.8%), above-ground biomass (63.4%), net revenue (68.4%), proportion of macroaggregates (> 0.25 mm) (35.7%), mean weight diameter (MWD) (78.4%), soil organic carbon (7.0%), and heavy fraction organic carbon (10.3%) in all three crop systems compared to no-mulch. Re-used mulch significantly increased topsoil temperature (11.4% above average), moisture (13.4%), and MWD after final crop harvest (19.1%) in all three crop systems; and significantly increased crop yield (61.8%) and above-ground biomass (50.3%) in the faba bean system. However, re-used mulch had no significant effect for the grain and forage maize systems compared to no-mulch. The 2-years re-used mulch (3-years continuously mulch) had significantly lower plastic film residue (57.1% below average) after final crop harvest in all three crop systems. Re-used mulch also produced significantly higher net revenue (13.2%) in the faba bean system compared to new mulch. In summary, cropping faba bean, under re-used mulch, instead of new mulch, significantly reduce the usage and residue of plastic film and resulted in similar high productivity, and may become a willingly adopted practice for farmers due to the higher net revenue. This work can serve as a reference for sustainable use of plastic film mulch and has potential applications to effectively reduce plastic film usage and residue in cropland and develop sustainable agriculture, especially for cultivating faba bean and other temperature-insensitive crops in developing countries.