Long-term straw mulch underpins crop yield and improves soil quality more efficiently than plastic mulch in different maize and wheat systems

Context: Field mulching efficiently increases crop production, yet the feasibilities of plastic mulch (PM) and straw mulch (SM) in different ecological regions are scarcely documented. Objective: This study aimed to investigate yield responses and soil quality changes following PM and SM, thereby identifying their suitability in different maize and wheat systems. Methods: A total of 202 peer-reviewed publications after 2000 that involved field experiments treated with nomulch, PM, and SM were collected, and yield ratio of PM to SM (RPM/SM) was calculated to quantitatively understand their mulching efficacy. Results: PM significantly increased grain yields in mono rather than double-cropping systems relative to SM, with an averaged RPM/SM at 1.28 in mono-maize, 1.11 in mono-wheat, and 1.05 for maize and 1.04 for wheat in double-cropping systems. Growing-season precipitation was significantly correlated with RPM/SM across mono and double-cropping systems, showing an RPM/SM of 1 at 530-mm for wheat in mono-cropping and 395-mm in double-cropping, and a stabilized RPM/SM observed at 1.082 in mono-cropping and 1.001 in double-cropping for maize, when growing-season precipitation exceeded 576-mm and 500-mm, respectively. Long-term field experiments illustrated significant relationships between RPM/SM and experimental duration, showing an RPM/SM of 1 at the 10.3-year for mono-maize, and 14.6-year for maize and 16.7-year for wheat in double-cropping, and a stabilized RPM/SM of 1.075 when trial time exceeded 3.7 years for mono-wheat, indicating a logged better performance of agronomic yield for SM. Owing to remarkable increases of soil organic C (SOC), total N, available K, and microbial biomass C, SM received the highest soil quality index across mono- and double-cropping systems, compared with PM and no-mulch. Growing-season precipitation, soil moisture at the sowing stage, SOC, and total N are the vital climatic and physicochemical variables mediating RPM/SM regardless of mono and doublecropping systems. Conclusion: Long-term SM rather than PM is an alternative for addressing the triple challenges of food security, soil degradation, and environmental mitigation. Implication: Quantifying the mulching efficacy on crop yields in different maize and wheat systems contributes to underpinning soil fertility and productivity in water-limited areas.