An integrated decision model for evaluating alternative swine waste management systems under environmental constraints in Oklahoma

The objectives of this study were to evaluate the economics of alternative swine waste management systems and to determine the optimal waste management strategy that maximized a representative swine producer's profitability from production while managing swine waste in a manner that meets environmental regulations. The objectives were accomplished through the use of an integrated mixed integer decision model. The model was used to determine the most profitable swine production and waste management system for representative producers in Texas and Seminole counties of Oklahoma. The result showed that there was no single best or optimal waste management system for all sizes and types of operations. The most profitable system across all the sizes of operations in Texas county was found to be the lagoon with a pivot irrigation system while the second best system was the pit with a traveling gun system. In Seminole county, the pit system with a traveling gun irrigation was the most profitable system for operations with less than 2,000 head. The lagoon system with a traveling irrigation was the most profitable for operations over 3,000 head. In general, the waste management systems that stores waste in lagoon and spread the waste through an irrigation system required less energy and labor and were more cost effective than were those which used tanks and tractors to haul the waste to the field. The per animal costs of all manure handling systems decreased as the one time capacity increased up to the maximum of 10,000 head. Adoption of rules which require a minimum number of acres of land for waste disposal per animal unit have less effect on swine producers using lagoon systems than those using a pit system. However, adoption of nitrogen and/or phosphorus based limits on waste application rates would result in much greater income reductions for larger operations than would the use of nitrogen limitations alone. Imposing a regulation to cover outside waste storage as was done in Iowa rule would reduce producers' profits so much that many firms would no longer be profitable.