Feedlot manure nutrient loadings on South Dakota farmland

Abstract

AbstractA key determinant of whether livestock manure is an asset or liability for agricultural producers and for society more generally is the amount produced relative to the nearby farmland area to which it can be economically transported for application. The objectives of this study are to estimate manure N and P loadings on the cropland and rangeland associated with 78 feedlot farm operations in South Dakota and to determine if they are greater for larger feedlots.A substantial fraction of the feedlot operators studied apply plant-available N and P in livestock manure at rates that exceed crop and grass fertility requirements, and intensity of manure nutrient loadings on cropland is strongly and positively related to feedlot size. These findings raise a warning regarding possible nonpoint-source pollution of vulnerable water resources from manure produced by fed cattle in larger feedlots.