Economics of dairy waste use as fertilizer in central Texas

Dairy manure is an unavoidable natural, but negative, byproduct of milk production. Its nitrogen, phosphate, and potash contents represent a potential substitute for commercial fertilizers on field crops. In the absence of subsidies, manure transportation and land application costs limit its utilization as a substitute for chemical fertilizer. The results from a study of the economics of manure use in Central Texas suggest that, at the current costs for loading, hauling, and spreading, dairy manure cannot be economically transported from surplus to deficit areas within the study area. The estimated breakeven transport distance for manure application to four crops varied from 28 to 41 km; however, the distances between manure-surplus and manure-deficit counties in the study region varied from 40 to 90 km. An analysis of potential subsidies paid by the government or dairy farmers showed that the breakeven distance could increase by up to 30 km. A decrease in the assumed moisture content of the manure from 50% to 40% is shown to increase the breakeven distance by 10 km. The study suggests that dairy manure loading, transportation, and land application, with appropriate subsidies or reductions in moisture content, has the potential to be profitably substituted for chemical fertilizers. © 2005 Elsevier Ltd. All rights reserved