Hydrothermal conditions impact yield, yield gap and water use efficiency of dryland wheat under different mulching practice in the Loess Plateau

Mulching practice reduces evaporation, modifies soil temperature and thereby affects crop yields. But the effects of mulching practices on moisture preservation and yield increase are not consistent under different precipitation and temperature conditions. The Loess Plateau spans a wide range, with distinct spatiotemporal variation in its hydrothermal conditions, so the reported effects of mulching are sometimes contradictory. A meta-analysis was carried out to evaluate the impact of plastic film mulching (PFM) and straw mulching (SM) on grain yields and water use efficiency (WUE) of wheat based on data from 74 peer-reviewed publications. The results showed that PFM and SM were significantly increased wheat yield and WUE compared with no-mulching (CK). The impact of mulching on wheat yields was also affected by temperature and precipitation. PFM led to a large yield and WUE increase under low-temperature conditions, the yield and WUE under SM was significantly affected by temperature and precipitation. Compared with PFM, SM showed no yield or WUE increasement effect under high temperature with low precipitation (> 10 °C, ≤ 350 mm) or low temperature with high precipitation (≤ 10 °C, > 350 mm). Meanwhile, our study found that PFM may reduce the yield gap between potential and actual yields compared to SM. These results have important implications for choosing proper mulching practices to increase wheat yields and WUE in agricultural production under local hydrothermal conditions.