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Topics : Species and Forage Variety Trials : Species Fact Sheets : Kentucky Bluegrass

Species: Kentucky Bluegrass

Additional tall fescue information via the Forage Information System (FIS)


Kentucky Bluegrass Grazing or Harvest Management

Under normal environmental conditions in Pennsylvania, Kentucky bluegrass produces nearly 70% of its annual forage production by early June. Consequently, proper management during the early growing season is essential to maximize Kentucky bluegrass's production potential. Since Kentucky bluegrass is a short growing plant, compared to many other cool-season forage grasses, it is ideally suited for grazing.

Kentucky bluegrass pastures are often under grazed in the spring, which results in an accumulation of mature, low-quality forage. Use high stocking densities early in the growing season when Kentucky bluegrass is most productive or harvest excess growth as hay or silage. Reduce the stocking density later in the grazing season as grass growth slows. In hilly areas, grazing of Kentucky bluegrass should begin on south-facing slopes which warm first and begin growth early in the spring. Maintaining a stubble height of 2 to 4 inches in spring promotes tiller (new shoot) formation, which helps keep a dense sod. Excessive defoliation often results in shallow rooting, an open sod, and weed invasion. These effects are particularly damaging to Kentucky bluegrass in a dry summer when it is less able to recover. Kentucky bluegrass productivity is increased substantially with proper pasture rotation and rest.

Kentucky bluegrass has a large proportion of its leaves close to the soil surface and below the grazing height in managed pastures. This characteristic makes it more tolerant of over grazing than most other cool-season grasses. Consequently, tall-growing grasses will thin under abusive management while Kentucky bluegrass volunteers and thickens providing high-quality forage and protection from soil erosion. However, heavy stocking densities and continuos over grazing as is frequently the case in sheep and horse pastures, especially in midsummer when grass growth has slowed, will weaken Kentucky bluegrass and increase weed invasion.

As growth of Kentucky bluegrass declines in mid summer, livestock production on these pastures is also reduced, particularly during a dry growing season. In addition, grazing days per year and animal gains per acre are generally less on Kentucky bluegrass than other cool-season, tall-growing grasses. Exceptions to this trend occur at higher elevations and latitudes where temperatures and rainfall are not limiting.

The botanical composition of Kentucky bluegrass pastures changes over and within growing seasons depending on environmental conditions and grazing management. Under conditions of high temperatures, limited rain fall, or low soil fertility the amount of Kentucky bluegrass in a pasture will decline which allows the invasion of undesirable weed species. The ratio of Kentucky bluegrass and white clover in a pasture is strongly influenced by grazing management. As the amount of clover in the pasture declines, the pasture can be grazed more closely so that the grass competes less with the clover. If the amount of white clover in the pasture is too great, then allowing the pasture to reach a height of 8 to 12 inches will encourage the Kentucky bluegrass to compete better with the white clover. In addition, nitrogen fertilizer favors the Kentucky bluegrass component of the pasture and may be used to manipulate the clover to grass ratio.