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

Field mulching efficiently increases crop production, yet the feasibilities of plastic mulch (PM) and straw mulch (SM) in different ecological regions are scarcely documented. 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. A total of 202 peer-reviewed publications after 2000 that involved field experiments treated with no-mulch, PM, and SM were collected, and yield ratio of PM to SM (RPM/SM) was calculated to quantitatively understand their mulching efficacy. 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 double-cropping systems. Long-term SM rather than PM is an alternative for addressing the triple challenges of food security, soil degradation, and environmental mitigation. Quantifying the mulching efficacy on crop yields in different maize and wheat systems contributes to underpinning soil fertility and productivity in water-limited areas.