Treat and halt: Occurrence of spatially heterogeneous cropland degradation in the peri-urban area

Globally, city region food systems (CRFS) are suffering from constant disruption of supply chains by the ongoing shocks of weather, disease, and geopolitical crisis. Prioritizing the development of peri-urban agriculture (PUA) is widely perceived as a pathway to enhancing the resilience of CRFS. However, PUA is often plagued by persistent and complex land degradation threats. There has been little research on how to combat these threats. In order to bridge this knowledge gap, we selected a representative peri-urban area in northeast China and identified the mechanisms underlying spatially heterogeneous cropland degradation using geographic detector and gradient boosting decision tree statistical tools. The results indicate that the croplands under threat of contamination and fragmentation were clustered mainly at the urban periphery. Although industrialization and the construction of infrastructure were identified as factors contributing to degradation, their negative impacts may be offset by density control, as restrictions of the density of both industrial agglomeration (<0.125/km(2)) and road network (<3 km/km(2)) were found to be instrumental. Soil fertility was affected by both trickle-down and siphonic effects in the peri-urban area, exhibiting contradictory trends under different urban growth rates. Soil fertility benefits from proper agricultural intensification, but overuse of agrochemicals not only reduces the effect but inhibits the provision of other ecological functions. Unfortunately, zoning controls fail to prevent these degradation threats, especially in areas situated within 7 km of the urban periphery. This implies that landsparing strategies in the peri-urban area are not sufficient, and only by building a symbiotic interface that includes nature and agriculture as urban elements can the urban-rural dichotomy be overturned. Our findings support the global sustainable development of PUA.