Techno-economic optimization of community-based manure processing

Abstract. Livestock production is an essential economic and cultural enterprise in many communities. Increased livestock herd sizes and the urban encroachment on agricultural landscapes have created a challenge to manure management. Inadequate manure storages and insufficient agricultural land bases have resulted in increased manure application rates and poorly-timed applications to dispose of surplus manure volumes. Alternatively, producers are forced to haul manure longer distances to access additional agricultural fields. Producers and regulatory bodies alike are seeking alternatives to mitigate the adverse environmental and economic impacts of manure management practices. Community-based manure processing can offer an opportunity to implement advanced processing technologies at lower cost due to economies of scale advantage. This study presents a techno-economic optimization model for community-based manure to organic fertilizer production using manure granulation. The model determines the highest return on the investment at each organic fertilizer price point. The decision variables include: selection of participating farms, primary on-farm processing, and siting the central processing facility (or facilities). We used a dairy farms inventory from a watershed in Wisconsin to develop a case study for community-based processing. Sensitivity analysis was performed to analyze the impacts of market changes and subsidies on the investment.