Alfalfa

Alfalfa (Medicago sativa)

Plant Species
From Montana Interagency Plant Materials Handbook *
By S. Smoliak, R.L. Ditterline, J.D. Scheetz, L.K. Holzworth, J.R. Sims, L.E. Wiesner, D.E. Baldridge, and G.L. Tibke

Alfalfa is a herbaceous, perennial legume that has often been called the "Queen of the Forages." It is the most important forage crop in the United States. Alfalfa was brought to Mexico and Peru from Europe by the Spaniards in the 16th Century and into California around 1850. It was reported to have been introduced into Montana in 1900 and was the main subject of discussion at the Farmer's Institute. It is the leading hay crop in Montana with over 1.5 million acres harvested in 1991. For further information on alfalfa production, refer to MontGuide 8505, "Growing Alfalfa for Hay," and annual performance summaries.

Description

Alfalfa is basically a tap-rooted plant that may penetrate the soil to a depth of 30 feet or more. There are varieties that possess rhizomatous characteristics. Alfalfa is a medium-lived, perennial plant. The seedlings are not aggressive, but the established plants are very competitive, and will survive 20 years or more if not killed by disease. The stems grow erect and reach a height of 2 to 3 feet. The leaves are arranged alternately on the stem and are pinnately trifoliate. The flowers are borne on loose racemes, and vary in color from shades of purple to yellows and white. The crowns may produce as many as five to 25 stems.

Adaptation

Alfalfa is well-adapted to a wide range of climatic and soil conditions, but grows best on deep, loam soils that are well drained. It is relatively drought tolerant but also responds very well to irrigation. It tolerates some alkalinity, but does not do well on highly-alkaline or salty soils. It is not tolerant of flooding, waterlogging or poor soil drainage. It will withstand short periods of flooding if they occur before growth begins in the spring. Varieties currently being recommended for Montana have a high level of winterhardiness.

Good stands of alfalfa are essential for high yields, and can be obtained by planting high-quality, certified seed at a depth of not more than 1/2 inch in a well-prepared, firm seedbed. The phosphorus level of the soil in the field to be established in alfalfa must be brought up to a high level prior to seedbed preparation.

Use for Hay

Alfalfa leads all other perennial legumes as a source of hay in Montana. It should be harvested in the one-tenth bloom stage of growth to obtain high yields of high-quality forage. The most critical growth period for maintaining vigorous stands is in late fall. To maintain stand life, fall growth must be sufficient to permit the plant to have >30 days of growth to store large quantities of carbohydrates in the roots. Do not harvest or pasture fall regrowth until after a killing frost.

Use for Pasture

Alfalfa is very palatable and withstands grazing quite well. Bloat may be a problem, but poloxalene (bloat guard) premix or blocks are available. The bloat hazard is diminished if grazing is delayed until after the bloom stage, or the mixture consists of 50 percent or more grass and rotational grazing is practiced.

* The Montana Interagency Plant Materials Handbook (EB69) is no longer in print, but is available for viewing in
Montana County Extension Service and National Resource Conservation Service Offices.