The plant superficially resembles clover (a cousin in the same family), especially while young, when trifoliate leaves comprising round leaflets predominate.

[4] Alfalfa is a small-seeded crop and has a slowly growing seedling, but after several months of establishment, it forms a tough "crown" at the top of the root system.

[18] Registered insecticides or chemical controls are sometimes used to prevent this and labels will specify the withholding period before the forage crop can be grazed or cut for hay or silage.

[22] Alfalfa is widely grown throughout the world as forage for cattle, and is most often harvested as hay, but can also be made into silage, grazed, or fed as greenchop.

[37] It is moderately sensitive to salt levels in both the soil and irrigation water, although it continues to be grown in the arid southwestern United States, where salinity is an emerging issue.

[42] A nurse crop is sometimes used, particularly for spring plantings, to reduce weed problems and soil erosion, but can lead to competition for light, water, and nutrients.

Alfalfa cultivation is discussed in the fourth-century AD book Opus Agriculturae by Palladius, stating: "One sow-down lasts ten years.

"[49] The medieval Arabic agricultural writer Ibn al-'Awwam, who lived in Spain in the later 12th century, discussed how to cultivate alfalfa, which he called الفصفصة (al-fiṣfiṣa).

[50] A 13th-century general-purpose Arabic dictionary, Lisān al-'Arab, says that alfalfa is cultivated as an animal feed and consumed in both fresh and dried forms.

[53] In the North American colonies of the eastern US in the 18th century, it was called "lucerne", and many trials at growing it were made, but generally without sufficiently successful results.

Since North and South America now produce a large part of the world's output, the word "alfalfa" has been slowly entering other languages.

[55] The mower-conditioner has a set of rollers or flails that crimp and break the stems as they pass through the mower, making the alfalfa dry faster.

[61] The anaerobic fermentation of alfalfa allows it to retain high nutrient levels similar to those of fresh forage, and is also more palatable to dairy cattle than dry hay.

[68] Lucerne grown in Australia prior to the 1970s was from seed brought from Great Britain in the early years of colonization, with production most successful in the Hunter and Peel river valleys.

[69] Pest burdens from the spotted alfalfa aphid in the 1970s caused significant destruction of NSW lucerne paddocks, with surviving populations being used as parents for Hunterfield cv.

[75] Much of this seed industry is centred around the town of Keith, South Australia, also encompassing the neighbouring localities of Tintinara, Bordertown, Willalooka, Padthaway and Naracoorte.

[5] Western honey bees, however, do not like being struck in the head repeatedly and learn to defeat this action by drawing nectar from the side of the flower.

This species may bear either the purple flowers of alfalfa or the yellow of sickle medick, and is so called for its ready growth in sandy soil.

[84] Most of the improvements in alfalfa over the last decades have consisted of better disease resistance on poorly drained soils in wet years, better ability to overwinter in cold climates, and the production of more leaves.

[85] Alfalfa growers or lucerne growers have a suite of varieties or cultivars to choose from in the seed marketplace and base their selection on a number of factors including the dormancy or activity rating, crown height, fit for purpose (i.e., hay production or grazing), disease resistance, insect pest resistance, forage yield, fine leafed varieties and a combination of many favourable attributes.

In 2005, after completing a 28-page environmental assessment[87] the United States Department of Agriculture (USDA) granted RRA nonregulated status[88] under Code of Federal Regulations Title 7 Part 340,[89] which regulates, among other things, the introduction (importation, interstate movement, or release into the environment) of organisms and products altered or produced through genetic engineering that are plant pests or that there is reason to believe are plant pests.

[87] The USDA granted the application for deregulation, stating that the RRA with its modifications: "(1) Exhibit no plant pathogenic properties; (2) are no more likely to become weedy than the nontransgenic parental line or other cultivated alfalfa; (3) are unlikely to increase the weediness potential of any other cultivated or wild species with which it can interbreed; (4) will not cause damage to raw or processed agricultural commodities; (5) will not harm threatened or endangered species or organisms that are beneficial to agriculture; and (6) should not reduce the ability to control pests and weeds in alfalfa or other crops.

[97] In July 2010, 75 members of Congress from both political parties sent a letter to Agriculture Secretary Tom Vilsack asking him to immediately allow limited planting of genetically engineered alfalfa.

[106] The National Corn Growers Association,[107] the American Farm Bureau Federation,[108] and the Council for Biotech Information[109] warmly applauded this decision.

[113] In a joint statement, US Senator Patrick Leahy and Representative Peter DeFazio said the USDA had the "opportunity to address the concerns of all farmers", but instead "surrender[ed] to business as usual for the biotech industry".

[114] In March 2011, the non-profit Center for Food Safety appealed the deregulation decision,[115] which the District Court for Northern California rejected in 2012.

[119] With long-term human consumption of alfalfa seeds, several safety concerns and medication interactions may result, including possible reactions similar to lupus erythematosus, an autoimmune disease.

[120] Other concerns are for women during pregnancy or breast-feeding, hormone-sensitive conditions (such as breast, uterine, and ovarian cancers), and for people with diabetes.

Raw unsprouted alfalfa has toxic effects in primates, including humans, which can result in lupus-like symptoms and other immunological diseases in susceptible individuals.

[130] Grazing management can be utilised to mitigate the effects of coumestrol on ewe reproductive performance, with full recovery after removal from alfalfa.