Q: I keep my four horses on about eight acres of pasture, which is split into two large fields. I rest one pasture while the horses graze the other one. Overall, I think my fields look pretty good—the grass is mainly fescue and some clover, and I mow a few times in the summer to cut the weeds down.

            A friend suggested I consider some pasture improvement to reduce the weedy areas and possibly fertilize my fields to improve the quality of the grass. While I think my fields can “look” better, I wonder whether pasture improvement is in my horses’ best interest. All four of them tend to get fat, and I frequently have to muzzle them in the spring and fall so that they eat less. Should I fertilize and otherwise treat my pastures, given my horses’ condition, and if so, what do you recommend? Name withheld by request

A: If pastures are an important component of your nutritional program, it is always advantageous to keep them as healthy as possible. Vigorously growing forage plants will be better able to compete with weeds and survive periods of stress caused by weather, insects and diseases.

Some horses, like yours, may gain too much weight on healthy pastures. It is much better to reduce their access by using grazing muzzles or restricting turnout time than it is to allow the pastures to deteriorate. Short, overgrazed pasture grasses can be relatively high in sugar content and low in fiber, a combination that can lead to metabolic disturbances. In addition, overgrazed pastures develop bare spots that contribute to soil erosion, and weakened plants will be replaced by weeds and potentially toxic species.

In most areas, pastures can be maintained with little management at stocking densities of two to four acres per horse. At higher densities, however, good management is necessary . Here are some techniques that can help keep pastures healthy and productive:

  • Apply lime and fertilizer based on soil tests. Soil nutrient levels and pH (the measure of acidity of the soil) are extremely variable from farm to farm. Soil analysis can tell you the specific nutrients your soil lacks as well as whether lime needs to be applied to bring the soil pH to 6 or 7, which is best for forage plants. Consult your local Cooperative Extension office or analytical laboratory for soil test kits and directions on how to collect a sample.
  • Mow at regular intervals. Mowing promotes tillering (growth of new offshoots) of the grass, which leads to a dense, leafy stand and helps prevent the proliferation of weeds. If your pasture is composed primarily of fine-bladed, short-grass species, such as perennial ryegrass and bluegrass, maintain a mowing height of two to three inches. Mow to maintain a slightly higher level of three to five inches if your pasture is composed primarily of taller species such as orchard grass or timothy.
  • Reduce weeds. Encouraging grass growth and mowing may be enough to control weed growth. If, however, weeds continue to be a problem, an herbicide application may be appropriate. For best results, choose an herbicide effective against the specific species in your pasture and apply it at the right time of year. When using these products, follow all label directions and restrictions.
  • Renovate with reseeding. When renovating pastures, it is important to select the correct forage
    species.  Always match the forage species to your site conditions, management level and the stocking rate of your pastures. To ensure quality, purchase seed from a reputable dealer and choose seed mixtures formulated for horse pastures.
  • Rest your pastures. Repeated close grazing depletes energy reserves, reduces growth and will eventually kill a grass plant. This is especially true during adverse growing periods, such as a drought. A simple two-paddock system will improve pasture productivity: Put one cross fence across the pasture and rotate the horses between the two areas. Turn animals out on the pasture when the grass is six to eight inches tall and allow them to graze it down to three or four inches. Development of a system with more than two paddocks will provide additional improvements in pasture performance.

Donna Foulk
Pennsylvania State University
Cooperative Extension and Outreach,
Northampton County
Nazareth, Pennsylvania