If I own a farm that has two pastures that are approximately four acres each. How many horses can I graze in each pasture without having to worry about ruining the plant life?
The number of horses allowed to graze a parcel of land is called the stocking rate. Optimal stocking rate is contingent upon numerous factors including grazing behavior, level of pasture management, forage species, seasons, and weather patterns.
Grazing behavior plays a pivotal role in deciding how many horses can graze a certain piece of land. Horses prefer young plants because they are usually more succulent and tasty. Immature vegetation also offers more nutrients than older, taller plants. As such, horses will often graze pastures spottily, causing conspicuous areas of short and long forage (called lawns and roughs, respectively). In places of congregation, such as in the vicinity of feed troughs, waterers, gates, and shelters, horses may trample and destroy all forages. These barren patches are called sacrificial areas.
Pasture management includes mowing, fertilizing, reseeding, and weed control. Timely maintenance of pastures can boost stocking rate. One important aspect of pasture management is selection of hardy forages. Plants conducive to high stocking rates should be productive over a long growing season, should grow aggressively, and should not be hindered by high traffic. Because no single species of forage meets all of these criteria, a combination of grasses and legumes will provide the highest yields and the greatest variety in diet.
Time of year and weather patterns affect stocking rate. More horses can benefit from a forage stand in times of high production such as during a flush of growth in the spring. As spring and summer progress, forage production may decrease and reduce the stocking rate of a pasture. Slow or arrested plant growth, such as that caused by drought, could limit stocking rate significantly.
Considering these factors, the stocking rate for properly tended pastures in temperate climates is one to three acres per horse. A four-acre pasture could easily withstand the grazing of one or two horses. If the pasture is managed intensely or if grazing time is limited, it may be able to offer sufficient forage to sustain three horses.