Mulching improves yield and water-use efficiency of potato cropping in China: A meta-analysis

China is the world's largest producer of potato (Solarium tuberosum L.). Potato productivity in China is limited by water shortage. Mulching applications can effectively modify the plant hydrothermal micro-environment. However, the impacts of mulching on potato yield vary with climatic conditions and field managements. Here, we conducted a meta-analysis to evaluate the effects of plastic mulching and straw mulching on the yield and water-use efficiency (WUE) of potato cropping in China using data obtained from 131 peer-reviewed publications. The results showed that plastic mulching and straw mulching increased potato yield in average by 24.3% and 16.0%, respectively. The effects of mulching on the WUE of potato were also improved by 28.7% (plastic mulching) and 5.6% (straw mulching). At regional scale, plastic mulching performed better in Northeast China and Northwest China, while straw mulching performed better in Southwest China and South China. The yield and WUE of potato in response to mulching were affected by the mean growing season air temperature, water input, soil basic fertility and fertilizer applications. When compared to non-mulching control, the improvements of yield and WUE in potato were higher at mean air temperatures of 15-20 C-degrees than at temperatures below 15 degrees C or above 20 degrees C during the growing season for both mulching practices. Increase in potato yield under black film was significantly higher than that under transparent film when air temperature was over 20 degrees C. Potato yield and WUE increases in mulching treatments were greater in areas with a water input of 400 mm. The mean effects of mulching on the yield of potato were greater at relatively low ( 200 kg ha(-1))N rates. Similar trends were observed for P and K rates. In conclusion, this meta-analysis demonstrated that mulching increases the yield and WUE of potato in China and that the adoption of mulching practices should be site specific