Livestock Manure: a Nonpoint Source Environmental Hazard in South Dakota?

This exploratory study shows estimated manure nutrient loadings on cropland for 78 selected feedlots in South Dakota to be 4.7 times greater than for 62 selected cow-calf operations. For 44% of feedlots studied, the estimated amounts of manure nitrogen (N) spread on cropland exceed the 75 Ib/acre fertilizer N level recommended for corn with a 100 bu/A yield goal. For 40% of feedlots and 23% of cow-calf operations, amounts of manure N dropping on pasture exceed the 38 Ib/A recommended fertilizer N level for pasture land. Since the design capacity of feedlots covered in the study is nearly 10 times the average for all feedlots in the state and the average size of herd for the cow-calf operators studied is 1.35 times the state average, the estimated percentages of beef cattle operations studied with potential nonpoint pollution from animal wastes are considerably greater than for beef cattle operations generally in the state