Effects of Plastic Mulching and Plastic Residue on Agricultural Production: A Meta-analysis

China is a large agricultural country, and food security is significantly limited by the shortage of water resources. Plastic mulching technology can effectively modify the crop growth environment and crop production due to differences in climatic conditions, spatial distribution characteristics, and cropping systems and methods. In this study, a meta-analysis was conducted to quantitatively analyze the effects of plastic film mulching and residual plastic on yield and water use efficiency (WUE) of maize, wheat, potato, and cotton in China based on 266 peer-reviewed publications. The results showed that plastic mulching significantly increased crop yield (24.32%) and WUE (27.63%). Plastic mulching had the greatest effect of potato on yield (30.62%) and WUE (30.34%) in China. At a regional scale, plastic mulching performed best in Northwest China, and crop yield and WUE were influenced by film color, mulching method, and crop type. Black film and ridge row mulching were more favorable to crop growth and increased crop yield and WUE in arid areas of China. There was no significant effect on crop yield of residual plastic between 0 and 240 kg/ha, but the yield decreased significantly with increased time and residual plastic film >240 kg/ha. In conclusion, although plastic mulching can significantly increase crop yield and WUE, especially in dryland agriculture, we should also improve the technology for recovering residual plastic film to protect the environment.