WW-07540 Reviewed 2009
Why Care About Manure and Pasture Management?
Proper manure management is important for the health of horses and the environment. Ideally, manure should be removed from stalls daily. If allowed to accumulate in stalls, it can attract flies, harbor parasites and pathogens, increase the risk of thrush and other hoof-related problems, and generate offensive odors. Exercise paddocks may need weekly cleaning.
Manure should be spread evenly on cropland and incorporated into the soil to maximize its nutritional benefits to crops and minimize odor pollution. However, some horse owners may not have enough land to spread manure without overapplying, which creates a pollution hazard. If this is the case, rotationally grazing horses in pastures can help minimize manure buildup and manure-handling costs. If you have very little land, you might need to compost manure to reduce its nitrogen content and volume. Or you may wish to hire a pickup service or find a nearby landowner or farmer who can make productive use of your horse’s manure (Figure 1).
Horse manure is an excellent nutrient source for pastures and other field crops when properly applied at the optimum time and in the correct amounts. It contains nitrogen, phosphorus, potassium, sulfur, and micronutrients, and is high in organic matter. Proper application of manure’s nutrients can help reduce the need for costly supplemental fertilizers. Organic matter provided by manure enhances soil structure and water- and nutrient-holding capacity, reducing the soil’s susceptibility to erosion. Overall soil quality is enhanced with manure applications.
The nutrients in manure that boost plant growth can be a pollution hazard if the manure is improperly handled (Figure 2). For example, if manure is overapplied to fields, nitrogen in the form of nitrates can move into the soil and eventually into groundwater, a major source of drinking water for many rural homes and communities. Consumption of water with high nitrate levels can reduce the oxygen-carrying capacity of blood (methemoglobinemia). Nitrate consumption has also been linked to cancer. In light of this health risk, the Minnesota Pollution Control Agency (MPCA) explicitly prohibits the overapplication of nitrogen on pastures and other field crops.
Horse manure also contains phosphorus. When phosphorus enters lakes, rivers, and other surface waters, it stimulates the growth of algae, aquatic plants, and other vegetation. One pound of phosphorus can produce up to 500 pounds of aquatic plants. When these plants decay, they reduce oxygen to levels where many fish species cannot survive. Generally, phosphorus moves into surface waters when manure applied or stored on the soil surface is moved laterally, usually by rainstorms, into a drainage flow system toward the water. Even manure that has been worked into the soil can be a concern if the soil erodes into the water body throughout the year. Currently, no Minnesota law limits the amount of phosphorus that can be applied to cropland or pastures.
Minnesota’s feedlot program, created in 1971, helps protect the state’s waters from improperly managed manure. The MPCA, which administers the program, defines a feedlot as "any animal confinement area where a vegetative cover cannot be maintained, including poultry ranges, zoos, and race tracks and fur farms." Many recreational horse owners do not need to apply for a feedlot permit. You will need to apply for a feedlot permit if you operate a feedlot, manage 50 or more horses (in shoreland areas, 10 or more horses), and any of the following conditions exist:
More than half of Minnesota counties have accepted delegated authority under the MPCA’s feedlot program. In these counties, the county feedlot officer (CFO) is responsible for enforcing regulations and issuing permits for most feedlots. Hennepin County has not requested this administrative authority, so it is under the direct jurisdiction of the MPCA. Check with your county environmental officer or the MPCA regarding how state feedlot rules apply to your operation.
The Minnesota feedlot rule is currently under public review. Under the proposed rule, horse owners may need to register with the MPCA and abide by new land-spreading rules. In addition, the minimum number of horses for a feedlot designation may change. Check with the MPCA feedlot program hotline, (651) 296-7327 or (877) 333-3508, if you have questions about whether you need to register or apply for a permit.
In accordance with the Americans with Disabilities Act, this material is available in alternative formats upon request. Please contact your University of Minnesota Extension office or the Extension Store at (800) 876-8636.