| 英文摘要： |
The North China Plain (NCP) is one of the most important regions for food production in China; however, the typical winter wheat-summer maize cropping system has created a continuous decline in groundwater levels, triggering serious ecological problems. Additionally, changes in the evaporation potential in the NCP have altered from decreasing to sharply increasing. Therefore, it is critical to understand the actual cropland water consumption (i.e., the actual evapotranspiration, AET) and crop water use efficiency (WUE) under this new trend. This understanding is significant for agricultural water management in the NCP. This study investigated the historical AET and WUE trends for the winter wheat-summer maize cropping system during 1992-2014. This investigation was based on a long-term AET dataset obtained using a large lysimeter from 1992 to 2014 at the Yucheng Comprehensive Experiment Station of the Chinese Academy of Sciences near the Lower Yellow River. The results showed that annual AET decreased pre-2008 and rebounded post-2008. The rebound rate of annual AET from 2008 to 2014 was more than three times the annual decrease rate of AET from 1992 to 2008. The significant increase in summer maize AET mainly contributed to the rebound of the annual AET after 2008. Following the changes in AET and crop yield, the annual WUE had evidently increased for 1992-2008 and sharply decreased from 2008 to 2014. The significant decrease in winter wheat WUE mainly contributed to the annual decrease in WUE post-2008. Climate change, agricultural management, and crop yields were observed to regulate the changes in AET and WUE. In the context of accelerating climate change and the increased frequency of extreme climatic events, strategies to improve WUE by the Lower Yellow River have been proposed, which may also be helpful in the NCP and similar regions worldwide. |
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