Optimal manure utilization chain for distributed animal farms: Model development and a case study from Hangzhou, China

摘要

Manure management is a concern for many livestock and poultry producers all around the world. Manure is generated, processed, transported, and utilized in various ways. Manure management requires the coordination of animal feeding operations (AFOs), centralized processing facilities (CPFs), and crop farms. Such a manure utilization chain is more than an individual farm scale, and it is a complex nexus between different production systems. In this study, the manure utilization chain, which recognizes manure management behaviors at different units of a region, was proposed to ensure sustainable manure utilization for distributed animal farms. The goal of this study was to develop a regional manure utilization chain (RMUC) model to minimize annual manure utilization costs by identifying the optimal manure flow patterns among AFOs, CPFs, and crop farms. The model was implemented to evaluate the manure utilization chain in Hangzhou, China. The results showed that the average solid manure logistics cost was CNY 20/ton (1 CNY similar to 0.14 USD), and the average slurry manure utilization cost was CNY 25.4/ton when the manure nutrients were adequately distributed. If the solid manure processing capacities of CPF were optimized, the average solid manure logistics cost would be reduced to CNY 8/ton. This paper also discusses the cost of executing the manure land application setbacks (the minimum distance required between manure application areas and sensitive areas). If Hangzhou followed manure land application restrictions of Illinois, U. S, the slurry manure utilization cost (CNY 65.8/ton) would be 2.59 times greater than the cost (CNY 25.4/ton) in the current scenario. Manure management would be more similar to other waste management and rely on centralized strategy instead of individual farm management.