Can biodegradable film replace polyethylene film to obtain similar mulching effects on soil functions and maize productivity in irrigation region? A three-year experimental appraisal

Abstract

There is widespread controversy over whether biodegradable films (BFs) can replace polyethylene films (PEFs) to obtain similar mulching effects on crop yield and soil physicochemical properties in arid irrigated regions. To explore this issue, a three-year field experiment was conducted using two widely-used BFs (black and transparent BFs respectively) and traditional transparent PEFs as mulching materials to examine their aging characteristics and mulching effects in an irrigation maize field of northwest China (no-mulching as CK). The data revealed a noticeable decrease in surface integrity after aging for both BFs compared with PEFs, yet the surface cracks of BFs showed dispersed and randomly distributed characteristics. Particularly, BFs was not fully degraded within each growing season as desired, across 3 growing seasons. The aging properties of black and transparent BFs and their effects on soil functions were essentially indistinguishable. The aging of BFs significantly augmented the abundance of fragment- and fiber-shaped microplastics (MPs) in soils, relative to PEFs (p<0.05). Intriguingly, BFs mulching achieved comparable soil warming effects as PEFs did, under sunny and rainy days in each growing season. However, soil water storage at plough and deep soil layer for both BFs was significantly lower than that of PEFs (p<0.05). BFs mulching significantly improved the proportion of soil macroaggregates relative to PEFs (p<0.05), and evidently decreased soil bulk density (p<0.05). Moreover, it significantly improved soil labile organic carbon (LOC) content, while lowering soil total nitrogen, nitrate-nitrogen, and ammonium-nitrogen content relative to that of PEFs (p<0.05). Critically, relative to PEFs, BFs mulching harvested similar crop biomass and economic benefits, and better soil functions. The findings provided new insights into the reasonable usage and management of BFs for better sustainability in agricultural practice.