Identification of livestock farms with potential risk of environmental pollution by using a model for returning livestock manure to cultivated land

Livestock farms produce a large amount of livestock manure, which, if not disposed of properly, will become an environmental pollution source. However, limited research has been conducted on identifying livestock farms with a potential risk of environmental pollution. In this study, a model for returning livestock manure to cultivated land was constructed. Livestock manure was returned to cultivated land, and the amount of surplus livestock manure nutrients, including nitrogen and phosphorus, in livestock farms was calculated with pig manure as an example. Then, livestock farms with a potential risk of environmental pollution in Shanggan Town and part of Xiangqian Town in Fuzhou City were identified using phosphorus as an index. Results showed that the spatial distributions of nitrogen and phosphorus from pig manure in the cultivated land varied. All cultivated lands exhibited the maximum carrying capacity for phosphorus, and 1811 cultivated lands exhibited potential nitrogen carrying capacity. A total of 13,958.997 kg of phosphorus from pig manure in 144 livestock farms could not be disposed to cultivated lands. In all, 144 livestock farms with surplus phosphorus from pig manure were identified as potential environmental pollution sources. These findings can serve as a scientific basis for the utilization of livestock manure, prevention of environmental pollution caused by livestock farms, and layout planning of livestock farms.