Abstract:

To address the water−grain nexus in the groundwater funnel area of the north China plain, this study systematically analyzed the dynamics of soil water and the maize yield response by considering both precipitation (normal and dry years) and winter fallow practices (fallow, oilseed rape and hairy vetch) based on field experiments conducted during the maize growing seasons from 2022 to 2024 in the north China plain. The results showed that: (1) annual precipitation pattern and the distribution of rainfall during the maize season significantly affected the soil water storage of winter fallow practices. In the normal year with evenly distributed maize season rainfall (2022), soil water storage increased significantly, thereby reducing the risk of groundwater funnel development. In contrast, with precipitation occurring mainly in the later part of the maize season (2024), soil water storage at the maturity stage was needed to compensate for deficits earlier in the season. Winter fallow practices, especially fallow and oilseed rape, increased soil water storage. However, in the dry year (2023) with low and concentrated precipitation, winter fallow practices did not improve soil water storage, and the winter wheat treatment exhibited extra water consumption, further increasing potential risks to groundwater. (2) Annual precipitation pattern and fallow practices jointly affected maize growth traits and yield enhancement. In normal years (2022 and 2024), winter fallow practices reduced water consumption during the maize growing season and promoted kernel number development, resulting in yield increases of 0.81%−14.48%. In the dry year (2023), drought accelerated grain filling, leading to shorter but thicker ears and limited kernel number; only rapeseed treatment alleviated water stress through residue mulching and optimized water use, thereby stabilizing maize yield. This study suggests that fallow strategies in the north China plain should be dynamically adjusted in accordance with annual precipitation conditions, and attention should be paid to the cumulative effects of long−term fallow on soil water cycling to enhance the sustainable utilization of agricultural water resources.

Key words: Annual precipitation pattern, Winter fallow, Soil moisture, Water use efficiency