Determining the carrying capacity and environmental risks of livestock and poultry breeding in coastal areas of eastern China: an empirical model

The scale of regional livestock and poultry breeding (LPB) is generally not determined by the supporting capacity (fodder supply), but by the environmental carrying capacity of wastes from the LPB. The soil's own nutrient-supplying capacity used to be overlooked, which consequently produced an inaccurate result of carrying capacity estimation of the LPB. An empirical method was, therefore, employed to evaluate the soil's own nutrient-supplying capacity and further determine the carrying capacity and environmental risks of the LPB accurately. Thirteen counties along the coast of Jiangsu were selected to conduct this study, according to the framework of planting-breeding balance. Our results indicate that, including the soil's own nutrient-supplying capacity in the estimation of the carrying capacity of the LPB, it can reduce the original carrying capacity by 50%. This suggests that our empirical method can significantly increase the accuracy of estimating the carrying capacity of the LPB. The carrying capacity of the LPB in the study area varies from 1.5 to 48.08 pigs/hm(2), with a mean of 14 pigs/hm(2) based on phosphorus (P) balance. Furthermore, four sub-regions (Ganyu, Dongtai, Dafeng, and Guannan) that have a high P pollution risk should focus on controlling the scale of the LPB. The nitrogen (N) pollution risk in the study area is generally low. Results suggest that the soil's own nutrient-supplying capacity plays an important role in estimating the carrying capacity of the LPB accurately. This study can provide insights on reducing environmental risks of the LPB, which may be beneficial for decision makers.