Temporal and spatial variations in mulch film usage across prefecture-level cities in China from 2010 to 2015

Mulch film plays a role of growing importance in agricultural production due to its good capacities such as soil moisture retention, temperature increase, and weeding but its overuse can result in serious rural non-point source pollution and soil microplastic contamination. To investigate temporal and spatial variations of mulch film in China, this study conducted different approaches(e.g., spatial correlation, cold and hot spot, kernel density, and standard deviation ellipse analyses)based on data of mulch film usage in prefecturelevel cities and corresponding crop yields from 2010 to 2015. We found that mulch film usage in China increased from 1.18×106 t in 2010 to 1.45×106 t in 2015, but its increase rate decreased during the years. The national spatial correlation analysis revealed that mulch film usage exhibited a relatively high agglomeration state in China with a growing trend and a Global Moran ′ s Index reaching 0.627 9 at maximum in 2015. Based on the spatial distribution, most mulch usage mainly occurred at the eastern coastal region of China and parts of the Xinjiang region, while regions with the highest usage rate concentrated to the central and western parts in China. A 147 km westward move could be observed in the focus of mulch usage from 2010 to 2015, indicating a gradual increase in western China. The results suggested that the areas with a high agglomeration state and density of mulch film use(i.e., Huang – Huai – Hai Plain, hills in Zhejiang, Pearl River Delta, Sichuan Basin, and Xinjiang region)should be more concerned, and corresponding technologies(e.g., recycle and reuse of mulch)should be implemented to decrease the mulch-induced soil pollution in these areas.