Increased background precipitation masks the moisture deficit caused by crop greening in Northeast China

The discrepancy between water resource availability and agricultural production has become a dominant constraint on the sustainable development of agriculture. Recent satellite records have documented increasing vegetation growth since the 21st century, and this so-called "vegetation greening" has been unprecedented in the agricultural region of Northeast China. However, the influence of increased crop growth on regional water resources through the alteration of hydrological cycling remains unclear. This study investigated the impact of crop greening on the regional water balance in Northeast China using time-series satellite and observational records, machine learning, and numerical scenario simulations from WRF. Our results indicate that the enhanced water cycling during 2001-2020 in this region was characterized by a significant increasing trend in evapotranspiration, precipitation, and soil moisture. We found a complex sensitivity to the leaf area index (LAI) across Northeast China, with positive sensitivity in the southwestern regions and negative sensitivity in the typical black soil zones. The downwind precipitation induced by crop greening suggests that at the regional scale, the landscape pattern may play a more significant role in determining the water cycling response to crop greening. Our data driven and model-driven results indicate that the background precipitation increase was the dominant contributor to the soil moisture increase, which masked the water deficit caused by crop greening. We also found that the continuous precipitation increasing trend projected by CMIP6 could further relieve conflicts between agriculture and water resources. In summary, our study provides insights into the impact of crop greening on the regional water balance in Northeast China and highlights the importance of considering both landscape patterns and background precipitation changes in understanding the water cycling response to crop greening.