Abstract

Plastic mulch films are extensively used in arid and semi-arid agriculture to conserve soil moisture, regulate temperature, and stabilize crop yields under water-limited conditions. However, decades of intensive application have resulted in widespread accumulation of plastic residues and microplastics (MPs) in agricultural soils. This review synthesizes current knowledge on the agronomic drivers of plastic mulching, the generation and accumulation of mulch-derived MPs, transport pathways amplified by dryland conditions link agricultural soils to atmospheric and aquatic compartments, enabling downstream exposure of freshwater ecosystems and food webs. Evidence from long-term field surveys, laboratory experiments, and landscape-scale studies indicates that plastic mulching is a dominant source of polyethylene-based MPs in arid and semi-arid soils, with abundance increasing nonlinearly with duration of use. Wind erosion, drip irrigation, and episodic runoff facilitate vertical and horizontal redistribution, linking agricultural soils to atmospheric, aquatic, and groundwater compartments. MPs modify soil aggregation, hydraulic conductivity, microbial community structure, and nutrient dynamics, contributing to soil degradation and diminishing agronomic returns over time. While biodegradable mulches and improved recovery practices show promise, their long-term effectiveness under harsh dryland conditions remains uncertain. We conclude that sustainable dryland agriculture requires systems-level approaches integrating agronomic innovation, materials science, spatial monitoring, and regulatory frameworks to mitigate MP pollution while maintaining food security.

Key words: Agricultural plastic mulch; Arid and semi-arid regions; Microplastic transport pathways; Soil microplastics; Soil pollution and sustainability.