Climate and Soil Properties Affect Yield-Scaled CO2 Emissions Under Plastic Film Mulching: A Meta-Analysis

Plastic film mulching (PFM) is widely used in arid, semiarid, and seasonally arid regions, where it plays a key role in regulating agricultural productivity and CO2 emissions. Our study aims to clarify the effects of PFM on crop yield, CO2 emissions, and the associated tradeoffs, providing a theoretical basis for the sustainable use of PFM in agriculture. We conducted a meta-analysis to compare differences in crop yield, CO2 emissions, and yield-scaled CO2 emissions (YSC) between mulching and no mulching treatments while identifying factors influencing these outcomes. Our findings demonstrated that PFM enhanced crop yields of maize, wheat, and cotton by 33.2% (p < 0.001), 21.8% (p < 0.05), and 26.3% (p < 0.05), respectively. PFM stimulated CO2 emissions in maize fields by 36.8% (p < 0.001), while decreasing them in wheat and cotton fields by 11.8% (p < 0.05) and 8.1% (p > 0.05), respectively. Consequently, PFM significantly lowered YSC for maize by 39.3% (p < 0.05) and reduced it for cotton by 27.4% (p > 0.05), but led to a 38.3% increase in YSC for wheat (p > 0.05). For maize and cotton, when crop yields exceeded 6 t/ha, the YSC under plastic film mulching was higher than that under non-mulching. In contrast, for wheat, within the conventional yield range (below 10 t/ha), the YSC under plastic film mulching was lower than that under non-mulching. For cotton, the lowest YSC under PFM was achieved under the combined conditions of water inputs > 500 mm, air temperature > 8 °C, soil pH > 8, and N inputs < 200 kg N ha−1. For wheat, the lowest YSC under PFM was obtained under water inputs < 350 mm, air temperature < 8 °C, light-texture soils, and N inputs < 200 kg N ha−1. For maize, the lowest YSC under PFM was achieved under water inputs < 350 mm, air temperature < 8 °C, heavy-texture soils, soil pH < 8, and N inputs < 200 kg N ha−1. These insights offer guidance for the optimal use of PFM to enhance carbon efficiency and crop yield in agricultural systems.