Research on the spatio-temporal variation of agricultural film usage in China and the effect of threshold crop yield

Agricultural films (AGF) are widely used to improve crop yield, conserve soil moisture, and reduce herbicide use, but excessive application has caused substantial soil contamination. Using data from the China Agricultural Statistical Yearbook and the China Environmental Statistical Yearbook, this study systematically examined the spatiotemporal evolution and drivers of AGF usage in China from 1998 to 2022, employing standard deviation ellipse analysis, spatiotemporal statistics, correlation analysis, random forest modeling, and panel threshold modeling. Results show that AGF usage increased by 115.64%, rising from 120.69 × 10⁷ kg in 1998 to 260.26 × 10⁷ kg in 2016, before declining by 8.75% by 2022. The usage center shifted 235.91 km southwest, with policy-related factors-particularly construction occupation of farmland-showing an increasing influence (correlation coefficient + 64.35%). A usage threshold of 48,445 tons was identified, beyond which marginal yield benefits dropped sharply; in high-use regions, the yield increase effect of cultivated land construction was 11.5 times greater than in low-use regions (β = 111.225 vs. 9.670). These findings suggest differentiated management strategies: in high-use regions, enforce threshold-based caps on AGF input and accelerate adoption of biodegradable or recyclable alternatives; in low-use regions, increase input toward the threshold to optimize yield gains; and implement spatial controls to prevent AGF expansion into ecologically fragile southwestern areas. These targeted policies, grounded in quantitative evidence, provide a pathway to balance agricultural productivity with environmental sustainability.