Can dual mulching outperform single mulching in arid agriculture-Loess Plateau? A meta-analysis based on crop yield and water use efficiency

Field mulching is an important technique for dryland crop cultivation in the Loess Plateau (LP) of China, which alleviates the local agricultural water shortage. However, under different precipitation and temperature conditions, the effects of mulching on moisture conservation and yield enhancement are not consistent. A meta-analysis was conducted to assess the variations of mulching across various variables (mulching types, rainfall precipitation and annual average temperature) based on data from 203 peer-reviewed publications, including 1466 yield and 991 water use efficiency data points. The results indicated that compared with no mulching (CK), plastic mulching (PM), straw mulching (SM), and dual plastic and straw mulching (SPM) significantly increased both yield and water use efficiency (WUE), with SPM demonstrating the most substantial yield improvement. Under conditions of low temperature (<7 degrees C), PM significantly improved both crop yield and WUE. Similarly, when temperatures were below 7 degrees C and rainfall ranged from 400 to 600 mm, SM also significantly enhanced yield and WUE. Compared with PM, SM does not enhance yield and WUE under high-temperature low-precipitation (>12 degrees C, <= 400 mm) and low-temperature high-precipitation (<= 7 degrees C, >600 mm) conditions. SPM outperforms SM and PM in enhancing yield and WUE under diverse hydrothermal conditions. Furthermore, we conducted green development assessment using the DPSIR model, and after 20 years of development, we found that green development potential of SM and SPM is greater than that of PM. Overall, SPM not only enhances crop yield and WUE but also serves as an effective replacement for PM, thereby boosting crop production in dryland agriculture. Its crucial role in advancing regional green development has been validated by scientific research.