Comprehensive Comparative Advantage of Livestock and Poultry Farming Under Environmental Carrying Capacity Constraints: Evidence from Sichuan Province, China

The expansion and spatial concentration of livestock and poultry farming have intensified the mismatch between manure nutrient pressures and regional environmental carrying capacity, creating persistent obstacles to the sector’s green transformation. Using a balanced panel dataset covering 21 prefecture-level cities and autonomous prefectures in Sichuan Province from 2015 to 2024, we evaluate theoretical environmental carrying capacity (ECC), production comparative advantage (PCA), environmental comparative advantage (ECA), and comprehensive comparative advantage (CCA) under nitrogen and phosphorus constraints. The framework considers cropland as well as the potential nutrient assimilation capacity of grassland and forestland under suitable manure application conditions. We measure ECA by comparing residual carrying capacity per unit of actual livestock population with the provincial benchmark. We construct CCA using a signed geometric mean that preserves the direction of environmental constraints when ECA is negative. Prefecture-level spatial patterns are mapped using polygon-based choropleths. The Northwest Sichuan Ecological Economic Zone and the Panxi Economic Zone show the strongest PCA, while Zigong and Dazhou also retain production advantages outside these core areas. Under the nitrogen constraint, Ya’an and Panzhihua record negative ECA values. Under the phosphorus constraint, high ECA values are concentrated in Ganzi, Aba, and Liangshan. CCA is concentrated in western Sichuan and displays a clear spatial gradient, with the Northwest Sichuan Ecological Economic Zone ranking first under both nutrient constraints. These patterns indicate that the spatial layout of livestock and poultry farming should be better aligned with the existing production base, land-based nutrient assimilation capacity, and ecological protection constraints. Differentiated regional regulation, species-specific specialization, and coordinated manure recycling across land types can improve the fit between livestock production and environmental carrying conditions. The framework provides a quantitative basis for spatially differentiated livestock planning in Sichuan and can be adapted to other mountainous agro-pastoral transition regions through locally calibrated technical parameters and land-use assumptions.