Sustainable management practices to improve the water use efficiency of winter wheat in the North China Plain: a meta-analysis

Water shortage is a serious threat to agriculture production in the North China Plain. Sustainable management practices can improve the water use efficiency of winter wheat, but currently no academic consensus has been reached. Therefore, we performed a meta-analysis that included 2194 observations from 209 articles to assess the water use efficiency of wheat in this area. The groundwater provides for 34%–37% of wheat evapotranspiration, which increases the decline of groundwater levels. The management of wheat irrigation appears to be the key process in improving agricultural water use efficiency. We observed from regression analyses that the factors such as climate, soil, and management significantly affect the water use efficiency of wheat (p < 0.05). The data showed that nitrogen input and irrigation significantly increased wheat yields (p < 0.05), but irrigation did not significantly improve the water use efficiency compared to rain-fed wheat. The optimal water use efficiency was obtained when the irrigation amount was 80–160 mm, or irrigation was applied twice, or the seasonal irrigation amount plus precipitation was ≤ 240 mm. In contrast, a nitrogen input significantly increased evapotranspiration and water use efficiency. The water use efficiency improvement was especially prominent when the nitrogen application rate was 220–250 kg·ha−1. Moreover, subsoiling and straw return should be recommended for increasing yield, reducing evapotranspiration, and improving water use efficiency. These practices can ultimately save over 240 mm of water and 75 kg·ha−1 of nitrogen, which contributes to a sustainable agricultural development. Here, we demonstrate for the first time the impact of management practices on crop water use efficiency at a regional scale and propose a sustainable agricultural development scheme.