Alfalfa (Medicago sativa L.)

Common Name:

Alfalfa

Scientific Name:

Medicago sativa L.

Synonym:

Alternative common name is Lucerne.

Family:

Fabaceae

Tribe:

Origin:

Iran, Central Asia, Siberia. Initial introduction was followed by 8 other sources currently representing the germplasm used in modern US cultivars.

Time of introduction:

Introduced into Georgia by colonists in 1736, later into California (1850) and North Central States (early 1900s).

Description:

Alfalfa is a very palatable and productive herbaceous perennial legume with worldwide distribution. It is grown in every state in the US. Hundreds of different varieties have been developed. Growth habit is upright, with crowns having 5-25 stems growing 23-35 inches (60-90 cm) in height. Regrowth occurs from crown buds or axillary stem buds. Alfalfa has a prominant taproot. However, typically 60-70 percent of the root system is concentrated in the upper 6 inches (15 cm) of soil, with fibrous roots predominating and bearing most of the nodules. It is high yielding and high in quality, but requires high fertility and large quantities of water for optimum productivity. It is grown primarily for hay, but can be ensiled, or used as pasture, either alone or in combination with grasses (typically orchardgrass or smooth bromegrass). Dehydrated alfalfa can be pelleted, cubed, or sold as meal.

Life cycle (annual/biennial/perennial):

Long-lived perennial.

Growth habit & Regrowth type:

Growth habit is upright from a crown with 5-25 stems. Regrowth initiates from crown buds or axillary stem buds. Periodic defoliation (28-35 day schedule) is required to restore root carbohydrates.

Invasive potential:

Low. Although a long-lived perennial, spread is insignificant into unseeded, unmanaged areas.

Persistence:

Can be long-lived (20+ years) if managed to allow restoration of root carbohydrates. More typically, high quality harvest schemes (defoliating prior to flowering) limit stand life to 4-5 years.

Identification:

Image Gallery: The OSU Forage Information System contains an Image Gallery that includes Alfalfa photographs and drawings useful in identification. The URL for the gallery is: http://forages.oregonstate.edu/main.php?PageID=241

The direct URL for Alfalfa is: http://forages.oregonstate.edu/main.php?PageID=178&SpecID=1

Inflorescence: The alfalfa inflorescence is an oval or rounded raceme, with 4 to 40 flowers. They may be blue, yellow, or white but are typically purple or violet. Alfalfa raceme image.

Flower: Flowers are 10-25 mm long and 10-20 mm broad. The flowers contain both female (pistil) and male (stamen) structures. Alfalfa flower image.

Seed: Alfalfa seeds are yellow or olive-green to brown. They are irregularly reniform (kidney-shaped), with about 200,000 seeds per pound (440,000/kg). Alfalfa seed image.

Stem: Mature alfalfa plants have slender, glabrous (hairless) stems with multiple branches. A mature plant has 5 to 25 stems, reaching a height of 23-35 inches (60-90 cm). The alfalfa plant spreads by crown enlargement. Some new grazing types have rhizomes.

Leaf: Alfalfa leaves are pinnately trifoliolate (three leaflets per leaf) with the terminal petiolule longer than the side petiolules. The upper one-third of the obovate-oblong leaflets are toothed or serrated. Leaflets measure 10-45 mm long and 3-10 mm broad. Alfalfa leaf image.

Stipules: The nodes (where the leaf joins the stem) have triangular, tapering stipules which are united for one-half to one-third the stipule length. The stipules have teeth and sharp pointed tips. Alfalfa stipule image.

Root: Alfalfa has an extensive taproot which may penetrate the soil 23-30 feet (7-9 m). It is not unusual, however, for the root system to be highly branched. Fibrous roots proliferate in the upper 8 inches (20 cm) of the soil profile, bear most of the nodules, and constitute 70% of the total root mass. Alfalfa taproot image. Alfalfa nodules image.

Physiology and growth period:

Alfalfa is a cool season (C3) legume; growth initiates at 46-50 F (8-10 C), stops at 95 F (35 C). Optimal day/night temperature for yield is 80/70 F (27/21 C). It is able to fix atmospheric nitrogen (N2) for its own growth and associated grasses. Regrowth comes from crown buds or axillary buds with 3-4 harvests common throughout the US.

Reproduction:

Seed production is by insect-assisted cross pollination. Alfalfa flowers must be tripped to set seed. Tripping is the release of the sexual column from the keel of the flower and can be caused by many insects, including Megachile rotundata F (the alfalfa leaf-cutter bee), Nomia melanderi Ckll. (the alkali bee), and bumblebees (Bombus spp.). Honeybees (Apis mellifera L.) are effective trippers when they gather pollen or when the nector collectors are sufficiently numerous. At present, the honeybee, akali bee, and leaf-cutter bee are propagated for alfalfa pollination.

Quality/anti-quality factors:

Alfalfa has the highest feeding value of all commonly grown hay crops when harvested at late bud or early flower stage of maturity, while also being one of the most palatable and nutritious. Alfalfa produces the greatest amount of protein per acre of any livestock feed, and is often used in combination with corn silage in livestock rations to take advantage of the protein and energy content of the two feeds. When cut prior to bloom, it is low in fiber and high in energy. Thus, it is prized as a primary component in dairy cattle rations and is an important feed for horses, beef cattle, sheep, and milking goats.

Anti-Quality Factors
Bloat often is a problem for animals pastured on alfalfa and various clovers. Bloat is a distention of the rumen caused by an inability of the animal to eructate gases produced in the normal process of fermentation. Unfortunately, the methods of controlling bloat are troublesome, expensive, and only partially effective. Using a grass-legume mixture in pastures, supplementing legumes with grass hays, intensive strip grazing with electric fences, and drylot feeding have all been somewhat successful.

The most effective treatment involves using bloat-preventative materials. These anti-foaming compounds may be added to drinking water, applied as a top-dressing on grain supplements, included in pellets, or added to salt-molasses blocks supplied on pasture. However, the effectiveness of these methods is variable and depends upon animals obtaining a regular supply of bloat preventative.

Photographs/drawings:

Adaptation:

Suitability zones:

Alfalfa is worldwide in its distribution and is grown in every state of the US, accounting for nearly 30 million acres (12 million ha) of production. A wide range of soil and climatic conditions are suitable for alfalfa, but for best production it requires a well-drained soil with nearly neutral pH and good fertility.

Fall Dormancy/Winter Hardiness Classes As a species, alfalfa is grown from cold-temperate to subtropical climate zones. Cultivars are grouped from 1(very dormant/winter hardy) to 11 (non-dormant/not winter hardy).

Map:

Tolerances:

Alfalfa grows under many diverse environmental conditions. Temperature stress, however, limits its growth, yield, and stand longevity. Increases in winter hardiness have been achieved by hybridization of M. sativa and M. falcata.

Quantitiative Table:

July
Max Temp (C)
Jan
Min Temp (C)
Annual
Precip (mm)
Soil pH Soil Drainage
(categories)
Soil Salinity
(mmhos/cm)
Low High Low High Low High Low High Low High Low High
Well Adapted 22 34 -25 9999 400 1175 6.5 8.0 WD MWD 0 2
Moderate 20 35 -25 9999 300 1500 6.2 8.2 ED MWD 0 4
Marginal 18 36 -25 9999 100 2500 6.0 8.5 ED SPD 0 6
1. For the High values for January Minimum temperature and Annual Precipitation: "9999 is entered to indicate no limit to the high values for this tolerance category."
2. For Soil Drainage categories, " Abbreviations are used for Soil Drainage categories: VPD (very poorly drained), PD (poorly drained), SPD (somewhat poorly drained), MWD (moderately well drained), WD (well drained), SED (somewhat excessively drained), ED (excessively drained)."

Climate: When gradually acclimated through proper fall management, alfalfa can survive temperatures below -13 F (-25 C). It can tolerate temperatures above 122 F (50 C), and is highly drought tolerant. It grows best in areas with moderate rainfall or on irrigated, dry climates of the western US.

Soils: Alfalfa yields best on a deep, permeable soil with good soil moisture supplying capacity or irrigation during the growing season. It is very sensitive to poor drainage and compacted soil conditions that restrict root growth. Thus, alfalfa is most productive on loam or loamy soils that are both well drained and have good moisture-holding capacity. Alfalfa does not tolerate acid soils (pH below 6.2), especially in the seedling stage. This is partly due to nodulation requirements and partly to sensitivity to manganese and aluminum present at low pH levels.

Grazing Management: Alfalfa can be grazed throughout the growing season in most areas, or can be used for grazing during selected seasons. Rotational grazing for short grazing periods of five to seven days with the long recovery period of 28-35 days is the major key to successful season-long grazing and maintaining productive stands. Avoid grazing during wet weather when alfalfa is particularly susceptible to soil compaction and trampling. Begin grazing when alfalfa is about 4 inches (10 cm) high, managing the animals so that the average plant height does not exceed 6-8 inches (15-20 cm), while leaving some leaf area on the plants.

Turf Management: Alfalfa is not used as a turf species.

Pests: Diseases: More than 20 diseases are serious problems for alfalfa. It is susceptible to verticillium wilt, bacterial wilt, fusarium root rot, spring black stem, sclerotinia crown, and stem rot. Determine the diseases common in your area and select a cultivar with a high level of resistance. The National Alfalfa Alliance (formerly Certified Alfalfa Seed Council) publication on Fall Dormancy & Pest Resistance Ratings for Alfalfa Varieties is a good reference.

Pests: Insects: Insects that interfere with forage and seed production include the potato leafhopper, alfalfa weevil, spotted alfalfa aphid, pea aphid, blue alfalfa aphid, alfalfa plant bug, and the meadow spittlebug. Choose cultivars resistant to prevalent insects in your area and use integrated pest management technique for control.

Fall Dormancy & Pest Resistance Ratings for Alfalfa Varieties - National Alfalfa Alliance

Pests: Nematodes: Alfalfa stem nematode (Ditylenchus dipsaci (Kuhn) Filpjev), root-knot nematodes (Meloidogyne spp.), and root-lesion nematodes (Pratylenchus spp.) are the most prevalent nematode species on alfalfa. Resistant cultivars are available. Resistance levels of certified varieties are listed on the Fall Dormancy & Pest Resistance Ratings for Alfalfa Varieties publication distributed by the National Alfalfa Alliance.

Cultivars:

Five general types of plant-breeding procedures have been used to develop alfalfa cultivars. These include plant introductions, improved populations, synthetics, hybrids, and strain crosses. Many cultivars have been developed to increase multiple pest resistance, which uses the practice of strain crossing so plant breeders can quickly incorporate multiple resistance traits.

Vendors:

Vendors will not be part of the "beneficial species white papers."

See the Forage Information System variety database for a listing of vendors.

Establishment:

Alfalfa performs well on deep, permeable soils with adequate moisture supply. A good seedbed for alfalfa is finely pulverized, leveled, and firmed to the seedling depth and contains soil moisture near the surface to initiate germination.

Seeding rate:

Although 12 pounds per acre (13.5 kg/ha) planted in 6-inch rows is usually sufficient, typical seeding rates are about 20 lbs/a (23 kg/ha).

Seeding depth:

Plant 0.25 inch (0.6 cm) deep; seedling emergence is reduced if planted more than 0.5 inch (1.25 cm) below the surface.

Fertilization and liming:

A productive alfalfa crop is a heavy user of plant nutrients. A complete fertilizer program is essential to a long-lived stand. Applications of fertilizer and lime should be based on the results of a soil test. Lime applications are required on soils having a pH below 6.2. Apply lime well in advance of seeding, mixing thoroughly with the surface 6 inches (15 cm) of soil. Fall applications provide time for soil reaction to take place and avoid the spring rush that often will delay planting.

Phosphorus can be applied by banding 1 inch (2.5 cm) to the side and below the seed when seeding, but is most often applied by broadcasting, followed by shallow incorporation, just prior to seeding.

Potassium, sulfur, and boron should be worked into the seedbed just prior to the seeding operation. Potassium and boron should not be banded near the seed. Nitrogen fertilizer is not required on legume forages because of the fixation of atmospheric nitrogen by effective nodules. Addition of nitrogen fertilizer will reduce the effectiveness of the natural nitrogen-fixing mechanism. If applied as part of other fertilizers (i.e. single ammonium phosphate), N application should not exceed 40 lb/a (45 kg/ha). Specific fertilizer recommendations based upon soil test data are provided in state Extension Service fertilizer guides.

Uses:

Alfalfa is used primarily as a forage crop with greatest acreage planted for hay. Alfalfa also can be made into silage, pellets, meal, or cubes. With careful management, alfalfa can be used successfully as a pasture crop. Alfalfa is also the primary honey crop in the US. It accounts for about one-third of the annual honey production by honeybees. Some honey production results as a by-product of seed production. Alfalfa's nitrogen fixing ability and deep rooting characteristics make it valued as a soil improvement and soil conservation crop.

Seed crop:

Areas with low relative humidities and moderate to high temperatures are preferred for alfalfa seed production because of a low incidence of leaf disease, long periods of pollinator activity, and favorable harvest conditions. About two-thirds of US alfalfa seed is produced under irrigation in five western states: California, Idaho, Nevada, Oregon, and Washington. South Dakota and Kansas produce significant quantities of seed under dryland conditions. Seed yields in excess of 4,630 lbs (2,100 kg/ha) have been reported, but average seed yields vary from about 670 lbs/a (750 kg/ha) in the western US to about 45 lbs/a (50 kg/ha) in the midwestern states.

Forage:

Alfalfa is usually produced for hay or silage. It can be mixed with corn silage to compliment the energy from corn and produce a very efficient feed for dairy animals. Preservation of alfalfa as silage helps to decrease field losses because less drying time is needed, therefore minimizing leaf shattering. Alfalfa can also be dehydrated and sold as meal, pelletted, or cubed. It also serves as a high-quality pasture for all types of livestock, and when mixed with grasses, the risk of bloat can be reduced.

Erosion Control/Conservation:

In addition to supplying nitrogen to the soil, alfalfa can also reduce water runoff and soil erosion, and improve soil tilth. Compared to soybean production, on 5% sloped ground, alfalfa reduced soil erosion 700-875%.

Wildlife habitat and feed:

Alfalfa provides significant habitat due to its nesting cover, abundant insects, perennial growth pattern, and feeding opportunities. The high palatability of alfalfa, which makes it such a good dairy feed, also makes it desirable to many herbivores, including many species of insects, rodents and grazing animals. Deer, antelope, and elk commonly feed in alfalfa fields, especially in times of drought. Foxes can be seen hunting rabbits and gophers, which feed on alfalfa fields. Many raptor species, including Swainson's Hawk and bald eagles, can be found hunting in alfalfa fields. Alfalfa is the beginning of a food chain that supports not only millions of farm animals and human beings, but many forms of wildlife that are important to the Earth's ecosystems.

Turf:

Alfalfa is not used as a turf species.

Economic value:

Seed:

Alfalfa seed is primarily grown in the northwestern areas of the U.S. primarily in the states of California, Idaho, Nevada, Oregon, Wyoming, and Washington. The approximate yield of alfalfa seed in the U.S. is 115 million pounds, with average price of $1.90 per pound ($4.18/kg), thus the estimated value of alfalfa seed is $218.5 million. A fringe benefit to the production of alfalfa seed is the production of honey from bees. In the U.S., approximately $100 million dollars worth of honey is produced each year.

Forage:

Alfalfa is the fourth most widely grown crop in the United States behind corn, wheat, and soybeans and double the cotton acreage. Although there is no published value for alfalfa hay the estimated value is $8.1 billion. There are 23.6 million acres (9.6 million ha) of alfalfa cut for hay with an average yield of 3.35 tons per acre (7.5 mt/ha). The estimated value of alfalfa hay is $102.50 per ton ($112.75/mt). Alfalfa meal and cubes are exported to other countries with a value of $49.4 million to the U.S. economy. The acreage of all alfalfa hay harvested, including alfalfa as a mixture with other forages, is approximately equal to wheat and soybean acreage.

Soil and water conservation:

"Green values" derived from soil improvement, reduced soil erosion, and improved water quality are difficult to quantify. Nevertheless, alfalfa contributes significantly to cropland soil improvement, stabilizing soil, and increasing water infiltration. Its extensive, deep, fibrous taproot system decreases soil density, improves soil structure, and decreases erosion.

Turf:

Alfalfa is not used as a turf species.

References:

  1. Anonymous. 1990. Alfalfa: The Crop for the Soil. Certified Alfalfa Seed Council. Kennewick, WA.
  2. Barnes, R.F., D.A. Miller, C.J. Nelson. 1995. Forages Volume 1: An Introduction to Grassland Agriculture. Iowa State University Press. Ames, Iowa. 16:206-215.
  3. Barnes, R.F., M.E. Heath, and D.S. Metcalfe. 1973. Forages: The Science of Grasslands Agriculture, Third Edition. Iowa State University Press. Ames, IA. 13:136-147.
  4. Becker, R., D. Cosgrove, J. Doll, C. Grau, K. Kelling, N. Martin, M. Rice, M. Schmitt, D. Undersander, and J. Wedberg. 1994. Alfalfa Management Guide. American Society of Agronomy. Madison, WI.
  5. Cheeke, P.R. 1998. Tosicoses associated with forages in general. Chapter 9: Natural Toxicants in Feeds, Forages, and Poisonous Plants. 2nd Edition, Interstate Publisher, Inc. Danville, IL.
  6. Cropper, J. 1997. National Range and Pasture Handbook. USDA NRCS. Fort Worth, TX.
  7. Fitzhugh, L., L. Godfrey, A. Kiess, J. Kuhn, R. Long, S. Orloff, D. Putnam, and M. Russelle. 2001. Alfalfa, Wildlife, and the Environment. Available at http://alfalfa.ucdavis.edu/subpages/Wildlife/BrochureFINAL.pdf (verified 14 July 2004).
  8. Hall, M. 1998. How an Alfalfa Plant Develops. Certified Alfalfa Seed Council, Inc. Kennewick, WA.
  9. Hannaway, D.B., et al. 2004. Alfalfa Information System [Online]. Oregon State University. Corvallis, OR. Available at http://forages.oregonstate.edu/is/ais/ (verified 14 July 2004).
  10. Hannaway, D.B. and W.S. McGuire. 1981. Growing Alfalfa for Forage. Oregon State University Extension Service Fact Sheet. Corvallis, OR. Available at http://forages.oregonstate.edu/resources/publications/fs/alfalfa.pdf (verified 14 July 2004).
  11. Hanson, A.A., D.K. Barnes, and R.R. Hill Jr. 1988. Alfalfa and Alfalfa Improvement. American Society of Agronomy. Madison, WI.
  12. Johnson, K. 2003. Purdue Forage Information System [Online]. Alfalfa. Purdue University. West Lafayette, IN. Available at http://www.agry.purdue.edu/ext/forages/publications/legumes/alfalfa.htm (verified 14 July 2004).
  13. Lacefield, G. 1993. Grazing Alfalfa. Certified Alfalfa Seed Council. Kennewick, WA.
  14. Putnam, D. 1997. History, Importance, and Production of Alfalfa in California. 27th National Alfalfa Symposium. San Diego, CA. Available at http://alfalfa.ucdavis.edu/subpages/AlfalfaHIST.htm (verified 14 July 2004).
  15. Putnam, D. 2004. California Alfalfa and Forages [Online]. Alfalfa Workgroup, University of California, Davis. Available at http://alfalfa.ucdavis.edu/ (verified 14 July 2004).
  16. USDA, NRCS. 2004. The PLANTS Database, Version 3.5 [Online]. National Plant Data Center, Baton Rouge, LA. Available at http://plants.usda.gov/cgi_bin/plant_profile.cgi?symbol=MEDIC (verified 14 July 2004).

Authors:

David B. Hannaway and Christina Larson, Oregon State University

Document creation:

15 June 2004

Last update:

13 August 2004

Reviewers:

Review date: