Abstract: Circular agriculture is essential for sustainable food supply, while substantially hindered by spatially decoupled crop-livestock systems. However, the decoupling extent of crop-livestock systems and effectiveness of recoupling strategies remain uncertain due to diverse-resolution investigations. Here we map China’s manure phosphorus (P) supply-demand balance from provincial to 1-km resolutions to represent multi-resolution crop-livestock linkages, and identify effective recoupling strategies by mathematical programing models. We find that resolution improvement substantially emphasizes the spatial mismatch of manure P supply-demand and high-density manure P surplus, implying coarse-resolution studies would underestimate the extent and intensity of crop-livestock decoupling whereas overestimating the area of manure P surplus regions. Compared to moderate livestock redistribution, manure transport is generally more effective at national scale for mitigating manure P surplus/deficiency; however, it is less effective in regions with severe manure surplus or large spatial extent. This study deepens the understanding of crop-livestock decoupling and the effectiveness of recoupling strategies.
图1. a The scale effect in spatial decoupling of crop-livestock systems. b Effectiveness of recoupling strategies (manure transport and livestock redistribution). The detailed descriptions are shown in the Methods section.
图2. a, b The manure P supply and demand patterns at provincial (ADM1), city (ADM2), county (ADM3), 10 km, 5 km, and 1 km resolutions in 2021. c The scatterplot of manure P supply-demand points. The white diagonal line represents the supply-demand balance line. d The coefficient of variations (CV) of manure P supply and demand (used for measuring spatial heterogeneity). e Cumulative amount of manure P supply/demand in regions with different densities of manure P supply/demand. f The Pearson’s r of manure P supply and demand in each spatial unit (used for measuring spatial mismatch). Basemaps are from the Chinese Resource and Environmental Science Data Platform (https://www.resdc.cn/).
图3. a Spatial patterns of manure P surplus and deficiency at provincial (ADM1), city (ADM2), county (ADM3), 10 km, 5 km, and 1 km resolutions in 2021. b The amount of manure P surplus and deficiency at each resolution. The red dotted line represents the total P surplus at the provincial level. c Cropland area in regions with P surplus, balance, and deficiency. d Distribution of P surplus and P deficiency with their densities. The black curve represents the share of intensive livestock farming. Basemaps are from the Chinese Resource and Environmental Science Data Platform (https://www.resdc.cn/).
图6. a The province-specific threshold manure transport distances and the reduced manure P surplus/deficiency of livestock redistribution within national- (LR-ADM0), provincial- (LR-ADM1), and city-level (LR-ADM2) boundaries, respectively. b–d are the spatial distributions of the threshold manure transport distance of LR-ADM0, LR-ADM1, and LR-ADM2, respectively. Basemaps are from the Chinese Resource and Environmental Science Data Platform (https://www.resdc.cn/).
第一作者：程明今
通讯作者：袁增伟