This study presents spatially explicit changes of soil phosphorus (P) pools in China's cropland during 1900-2010 using the Dynamic Phosphorus Pool Simulator (DPPS) to estimate the Phosphate Saturation Degree (PSD) in 2010, defined as the ratio of available P on sorption sites compared to the maximum P sorption capacity. Results indicate that a more than two-fold increase in P pools over 1900-2010 has led to a soil P saturation in circa 44% of Chinese croplands. The possible consequence in the next decades is enhanced P leaching and subsurface runoff. This pathway may cause a time‐delayed enhancement of eutrophication of lakes, streams, and rivers. The Yangtze and the South region, and the coastal areas like Guangdong, Zhejiang, and Fujian provinces, are the most vulnerable zones, indicating an urgent need to better manage soil P inputs. While measures to control erosion and surface runoff have direct effects on P losses to surface water, it is crucial to limit P input to crop uptake, or even mine P from the soils in case of large saturation, to reduce the delayed long-term risk of losses to surface water and limit eutrophication and coastal hypoxia.
 

China cropland, soil P pools, soil P saturation, spatial distribution, leaching risk, eutrophication