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Horse owners and commercial stable managers face environmental challenges. They need to develop a manure management system that uses the fertilizer nutrients in the manure without polluting the environment. They need pasture and paddock management to keep soil and manure on fields and out of streams and ponds. And finally, they need to get along with their neighbors.
Manure Management
Horse manure, including bedding, contains the fertilizer nutrients of nitrogen, phosphorus and potassium. Fortunately, plants need these nutrients to grow, but adding more nutrients than they need can pollute soils and water. In addition, manure contains disease-causing pathogens and parasites that also can pollute water systems. The trick is to put just enough manure on a field to help the crop grow and no more. If too much manure is applied, part of it may seep down and pollute groundwater and wells. Part of the manure may also wash into surface water like ditches, streams and lakes, polluting them.
To determine how much manure is enough, get a soil test for the field where you plan to spread the manure. This test will tell you the amount of fertilizer and manure nutrients that the crop needs. Estimate the amount of manure nutrients that your farm generates.
You can test the manure pile, but it is very hard to get a good, well-mixed sample to send to the lab. In general, a 1,000-pound horse will produce about eight tons of manure per year. A ton of horse manure has about four pounds of nitrogen, five pounds of phosphorus and nine pounds of potassium.
Manure Storage
Manure storage varies widely depending on the amount of bedding used. On average, however, a 1,000-pound adult horse bedded with wood chips or sawdust will generate about 25 cubic yards of manure and bedding per year. To limit runoff, manure should be stored at least 50 feet from any drainage way or water course and be surrounded by grass.
Check with the USDA Natural Resource Conservation Service (NRCS) office or your local Conservation District for technical help on building good manure storage structures. In some cases, state or federal funds may be available to help with the cost of building manure storage structures.
Pasture and Paddock Management
The basic environmental goals of horse pasture management are fairly simple. In a pasture, plenty of grass and other plants are good. Bare soil is bad. Brown water, from soil and manure running off of a bare pasture, is very bad.
Proper fertilization, fencing and feed- and watering-station layout can all increase a pasture's productivity. Keep in mind that it is generally better to have several small pastures than a single large one. It is also important to fence horses out of streams and ponds and to plan carefully any necessary stream crossings.
Depending on feeding goals and the region of the country, the recommended amount of pasture needed per horse ranges from about one-half acre to two acres. If you do not have ample pasture, you may need to limit the amount of time that horses are allowed out.
A small "sacrifice paddock," where the horses exercise when they cannot be on pasture, is an excellent management tool. Better yet, ask your local office of the USDA NRCS or Conservation District for help in designing a "horse exercise lot" or "heavy-use pad" for an all-weather horse exercise area.
Manure Treatment: To Compost or Not to Compost
Horse manure mixed with straw, old hay or paper-product bedding materials is very similar to other livestock manure. It can be used raw for crops. In general, these products are also easy to compost, which increases the number of disposal and use options.
Horse manure mixed with sawdust or woodchips is a totally different story. When these mixtures are spread on farm fields, they often stunt crop growth. This is because these wood products have a lot of carbon that soil microorganisms use for energy, but not enough nitrogen to build proteins. In other words, the microorganisms have an unbalanced diet and they need nitrogen. They find that nitrogen in the soil and collect it better than plants do. In fact, they do it so well that the plants growing in the soil cannot find enough nitrogen to grow properly. That is called an "induced nitrogen deficiency," and it stunts crops.
There are at least two, very different ways to overcome this nitrogen deficiency problem. One option is a nitrogen enhancement system in which specific nitrogen fertilizers are added to the manure as the stall is cleaned. The other option is to compost the materials.
