Modeling the Use of Sewage Sludge on Pennsylvania Dairy Farms: An Economic Analysis

A five-year linear programming farm planning model, permitting the inclusion of nitrogen decay rates, was constructed to include the use of sewage sludge as a primary crop nutrient source. Twenty-two scenarios depicting various operating conditions were examined and maximized net farm incomes compared. Although only a small percentage difference resulted between the highest and the lowest net revenues over the five-year period, given a variety of operating circumstances, those scenarios including the use of sludge yielded the highest net incomes. Nitrogen application restrictions were at their upper limits when sludge use was included in the optimal solution. The calculation of net present values, for the two sludge contents considered, provided value estimates compatible with the linear programming solutions.