Identifying the Influencing Factors of Plastic Film Mulching on Improving the Yield and Water Use Efficiency of Potato in the Northwest China

Potato is an important crop in the Northwest China, however, its production is constrained by water scarcity. Plastic mulching film is an efficient technical measure to alleviate potato production restrictions. Therefore, studying the response of potato yield and water use efficiency to plastic mulching film is of great significance. The study conducted a meta-analysis to quantify the effect of plastic film on potato yield and water use efficiency in the Northwest. The study then quantified the effects of different levels of natural conditions (mean annual precipitation, mean annual accumulated temperature ≥ 10 °C), fertilizer application (nitrogen fertilizer, phosphate fertilizer, potassium fertilizer), cultivation measures (planting density, cultivation method, mulching method), and mulching properties (mulching color, mulching thickness) through subgroups analysis. Finally, the random forest model was used to quantify the importance of factors. Plastic film mulching increased yield by 27.17% and water use efficiency by 27.16%, which had a better performance under relatively lower mean annual precipitation, low mean annual accumulated temperature ≥ 10 °C, relatively lower fertilizer application, planting density of 15,000–45,000 plants·ha−1, ridge, and black mulching. Natural conditions, fertilization measures were vital to improve productivity. The research results can provide reference for agricultural management strategies of potato cultivation using plastic film in the Northwest China and other potato-producing areas.