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Topics : Pastures : Strategies for Extending the Grazing Season

Strategies for Extending the Grazing Season

Additional pasture information via the Forage Information System (FIS)


The growth of some forage species is not as adversely affected by cooler fall weather and shorter day lengths as are many cool-season forages. The species which seem to grow best in the fall are tall fescue, prairie grass, perennial ryegrass, and certain brassica crops. These species can provide a valuable feed supply for extending the grazing season.

Prairie grass is a tall growing perennial grass that is suited to well drained soils with medium to high fertility levels and a pH of 6.0 or greater. It is a type of bromegrass, but is different from smooth bromegrass in that it does not have rhizomes and it produces seed heads in each growth period, especially during the summer. Herbage and immature seedheads of prairie grass are highly palatable. It is an excellent grass for providing forage during droughts and for extending the grazing season well into the fall in Pennsylvania.

Fall harvesting (grazing) improves the winter persistence of prairie grass. It will persist for four to six years in Pennsylvania if properly managed. Forage quality of prairie grass compares well with other cool-season grasses but is more palatable.

Adapted Varieties

`Matua' is the only cultivar of prairie grass that is currently sold in the United States. This variety was developed under New Zealand grazing conditions and has been very productive in Pennsylvania. Other prairie grass varieties are being evaluated for persistence and productivity by the USDA-Pasture Laboratory and Penn State; however, none of these varieties is marketed commercially in Pennsylvania at this time.

Grazing Management

Prairie grass is an ideal grass for grazing systems because of its potential for earlier spring grazing and its fall growth can effectively extend the grazing season by as much as two months over traditional cool-season grass species. Fall yields of nearly 3.5 tons/acre are possible. In addition, because seed heads are palatable, it is not necessary to mow them off to maintain animal intake as may be needed with other grasses. Yields of nearly 7 tons/acre have been achieved when harvesting prairie grass for silage.

Prairie grass should not be cut or grazed below a 3-inch stubble height because regrowth energy reserves and buds for plant regrowth are contained in this portion of the plant.

In established prairie grass stands, delaying the first spring grazing will reduce recovery rate and lower the yield potential of the next cutting. Under normal weather conditions, about 25 to 30 days of regrowth is sufficient between harvests. This period is a good balance between yield and quality of prairie grass. Generally, during this time, new shoots have developed at the base of the plant and harvesting or grazing will allow more light to reach the shoots and to stimulate their growth. An approximate 50-day growth period in mid-summer will allow the prairie grass seed heads to mature and drop seed during August which, in turn, will thicken the stand the following year.

Prairie grass persists best when managed so that monthly harvests are made during the fall; spring yield and shoot density increase when multiple harvests are made in the fall. Harvesting only once in the fall (November) has caused 98 percent of the basal shoots (source for growth the following spring) to winter kill. However, when prairie grass was harvested or grazed three times during the fall only 35 percent of the basal shoots were winter killed. Compromise is needed with regard to fall harvesting because late fall grazing reduces slightly prairie grass vigor the following spring and restricts early spring grazing.

Adequate nitrogen fertilization is essential for maximizing prairie grass growth in the fall. Nitrogen applications of 50 lb/acre are recommended after each harvest and in early fall.

For more information about Prairie Grass production and management.