Sub-area classification of environmental phosphorus loss risk in Yunnan's crop-livestock systems: a spatiotemporal...

Crop and livestock production in Yunnan province has experienced significant growth over the last decade. However, this progress has come at the expense of excessive phosphorus (P) losses to the environment, leading to ecosystem degradation and adverse effects on human health. As a result, there has been a growing focus on mitigating P losses within the crop-livestock systems (CLSs). Nonetheless, research on quantitatively analyzing the spatial and temporal distribution of P flows in these systems remains inadequate. Addressing this issue requires adopting an appropriate spatial scale for P management, which balances accurate regional representation with sufficient data granularity. Using statistical data, literature and geospatial data collected from 1995 to 2014, a time series and spatial distribution of P flows associated with CLSs was analyzed using the SFA model (Substance Flows Analysis). The results showed that total P inputs to crop systems increased by 52% (from 2.89 × 10⁵ t in 1995 to 4.4 × 10⁵ t in 2014) in Yunnan province. Concurrently, feed import as a dominant input to animal subsystems experienced a minor decrease over the same period. Application of P fertilizer was the main source of P inputs. Soil accumulation emerged as a prominent pathway, contributing to 50% of the total P output in 2014. Additionally, losses to water, stemming from terrain conditions and improper fertilizer application patterns, represented other notable pathways. A spatial analysis of P use efficiency categorized the region into three sub-areas comprising 16 municipalities. In region I, soil testing and fertilizer regulation could support targeted P fertilizer application based on the nutrient supplying capacity of soil and crop nutrient demands. Region II calls for the integration of crop and livestock production, while the region III would necessitate the expansion of animal production and advancements in manure management technology. This approach of sub-area classification presents a promising strategy for improving nutrient management in areas with complex terrain and diverse climate condition.