The effect of deficit irrigation combining with transparent/black film and straw mulching on wheat-maize cropping system in the North China Plain

Reducing agricultural water use and improving water efficiency are important ways to alleviate the main contradiction between the shortage of water resources and the increase in food demand. There is relatively little research on whether adopting water-saving irrigation during the winter wheat season affects the next season's maize. Determining the influence of mulching materials and irrigation methods on wheat-maize yield and water productivity serves as the foundation for developing effective water management strategies. Based on the rotation system of winter wheat and summer maize in the North China Plain, this study carried out field experiments from 2020 to 2022 by setting different irrigation amounts (full irrigation and deficit irrigation, FI and DI) and mulching measures (no mulching, NM; transparent film, TM; black film, BM; and straw mulching, SM). We studied the changes of soil water, crop yield, and other parameters. The optimal mode for water saving and yield-increasing in the North China Plain was revealed. The research results indicated when deficit irrigation was used for wheat, it had a negative effect on the soil water content, leaf area index and aboveground biomass of the winter wheat, resulting in a reduction of thousand weight and yield. But no similar conclusion was found in subsequent maize. When mulching measures were used under deficit irrigation for wheat, the TM treatment significantly increased the wheat-maize rotation (annual) yield and profit, but due to a significant decrease in the thousand-grain weight of wheat under the BM and SM treatments, no significant increase in annual yield and profit was found in them. The results showed that the transparent film mulching demonstrates optimal water-saving efficacy under deficit irrigation, but field application in great areas need to consider the collecting and recovery of film residue or use biodegradable alternatives to avoid plastic pollution.