Feedlot Manure Nutrient Loadings on South Dakota Farmland

A key determinant of whether livestock manure is an asset or liability in agricultural production and to society more generally is the amount of manure produced relative to the nearby farmland area to which the manure can be economically transported for application. The objectives of the study reported in this article are to (1) estimate levels of manure nutrient (nitrogen = N and phosphorus = P) loadings on the cropland and rangeland associated with 78 feedlot farm operations in South Dakota and (2) determine factors, including size-of-feedlot and cropland hectarages, associated with cropland N and P loadings for the feedlots studied. Findings from the study show that (1) substantial percentages of the South Dakota feedlot operators studied apply livestock manure plant-available N and P that exceed crop and grass fertility requirements and (2) greater intensity of manure nutrient loadings on cropland is strongly related to larger sizes-of-feedlot and smaller farmland areas on which manure is applied. These two main findings raise some potential red flags in regard to possibilities for non-point source pollution of vulnerable water resources from manure produced by fed cattle--both within South Dakota and in other major cattle producing states in the U.S