The harm of residual plastic film and its accumulation driving factors in northwest China

The background to this research is stark and rather troubling: the ongoing accumulation of residual plastic film (RPF) in farmland ultimately threatens the sustainable development of agriculture and food security. In this study, we selected 15 counties in northern China to analyze the effect of RPF content on soil properties and crop yield and the driving factors through sampling and survey questionnaire. The linear mixed-effects model revealed the four main factors affecting RPF content, ranked as follows: plastic film mulching years > government recycling policy > spacing between rows > recycling methods (0.47493 > 0.25635 > 0.23380 > 0.17001). The contribution value of plastic film thickness was very low (R²(M) = 0.099). The plastic film width and spacing within rows did not significantly affect RPF content. The structural equation model showed that the RPF had both direct (−0.111) and indirect (−0.010) effects on maize yield. A 1 kg ha⁻¹ increase in RPF content decreased maize yield by 27.67 kg ha⁻¹. RPF did not directly affect soil organic carbon (SOC), pH, or ammonium nitrogen. RPF mainly aggravated soil salinization by increasing soil nitrate-nitrogen, available phosphorus, and available potassium, increasing SOC and decreasing pH, thus reducing crop yield. To the best of our knowledge, this is the first study to combine the driving factors of RPF accumulation and the effects of RPF on soil properties and crop yield in a large-scale sampling and survey questionnaire. RPF accumulation in the study area has aggravated soil salinization and reduced crop yields. Hence, measures are needed to alleviate the current situation. Local governments should formulate RPF recovery policies based on their actual situation. At the national level, more research is needed to develop RPF recovery machinery to improve efficiency.