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Alfalfa (Medicago sativa L.) is a flowering plant in the pea family Fabaceae cultivated as an important forage crop. In the UK, Australia, South Africa and New Zealand it is also known as lucerne and as lucerne grass in south Asia. In Hindi known as chara, and in Gujarati as Rajka or Gadab. It resembles clover with clusters of small purple flowers.
This plant exhibits autotoxicity, which means that it is difficult for alfalfa seed to grow in existing stands of alfalfa. Therefore, it is recommended that alfalfa fields be rotated with other species (for example, corn or wheat) before reseeding.
Its primary use is as feed for dairy cattle—because of its high protein content and highly digestible fiber—and secondarily for beef cattle, horses, sheep, and goats. Humans also eat alfalfa sprouts in salads and sandwiches. Dehydrated alfalfa leaf is commercially available as a dietary supplement in several forms, such as tablets, powders and tea. Alfalfa is believed by some to be a galactagogue, a substance that induces lactation.
Like other legumes its root nodules contain bacteria, Sinorhizobium meliloti, with the ability to fix nitrogen, producing a high-protein feed regardless of available nitrogen in the soil. Its nitrogen-fixing abilities (which increases soil nitrogen) and its use as an animal feed greatly improved agricultural efficiency.
Alfalfa can be sown in spring or fall, and does best on well-drained soils with a neutral pH of 6.8 – 7.5. Alfalfa requires sustained levels of potassium and phosphorus to grow well. It is moderately sensitive to salt levels in both the soil and in irrigation water, although it continues to be grown in the arid southwestern United States where salinity is an emerging issue. Soils low in fertility should be fertilized with manure or a chemical fertilizer, but correction of pH is particularly important. Usually a seeding rate of 13 – 20 kg/hectare (12 – 25 lb/acre) is recommended, with differences based upon region, soil type, and seeding method. 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.
In most climates alfalfa is cut three to four times a year but is harvested up to 12 times per year in Arizona and southern California. Total yields are typically around 8 tonnes per hectare (4 short tons per acre) but yields have been recorded up to 20 t/ha (16 short tons per acre).
, Megachile rotundata, a pollinator on alfalfa flower]]
Alfalfa is considered an insectary due to the large number of insects it attracts. Some pests such as Alfalfa weevil, aphids, armyworms, and the potato leafhopper can reduce alfalfa yields dramatically, particularly with the second cutting when weather is warmest. Chemical controls are sometimes used to prevent this.
There are several types of bales commonly used for alfalfa. For small animals and individual horses, the alfalfa is baled into small two string bales commonly named by the strands of string used to wrap the bale smallest two string, three string, and so on up to half ton bales six string "square" bales — actually rectangular, and typically about 40 x 45 x 100 cm (14 in x 18 in x 38 in). Or they can be handled with a grapple (claw) on the tractor's front-end loader. A more recent innovation is large "square" bales, roughly the same proportions as the small squares, but much larger. The bale size was set so that stacks would fit perfectly on a large flatbed truck. These are more common in the western United States.
When used as feed for dairy cattle alfalfa is often made into haylage by a process known as ensiling. Rather than drying it to make dry hay, the alfalfa is chopped finely and fermented in silos, trenches, or bags, anywhere where the oxygen supply can be limited to promote fermentation. 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. In many cases, alfalfa silage is inoculated with different strains of microorganisms to improve the fermentation quality and aerobic stability of the silage.
Within the United States, the leading alfalfa growing states are California, South Dakota, and Wisconsin. The upper Midwestern states account for about 50% of US production, the Northeastern states 10%, the Western states 40%, and the Southeastern states almost none. Alfalfa has a wide range of adaptation and can be grown from very cold northern plains to high mountain valleys, from rich temperate agricultural regions to Mediterranean climates and searing hot deserts.
Most varieties go dormant in the fall, with reduced growth in response to low temperatures and shorter days. 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. Multileaf alfalfa varieties have more than three leaflets per leaf, giving them greater nutritional content by weight because there is more leafy matter for the same amount of stem.
The California Alfalfa Workgroup (UC Davis) has an up to date listing of Alfalfa Variety Trial Data by location as well as Agronomy Progress Reports for each year.
Even though Monsanto technically won, the most important parts of the lower court's decision were upheld, meaning there are still many regulatory hurdles GM alfalfa has to clear before it can be legally planted on a commercial scale. And in a decision that may have wide-reaching effects on future GM cases, the justices agreed that GM crops could cause environmental harm through cross-pollination.
Category:Legumes Category:Medicago Category:Faboideae Category:Forages Category:Vegetables Category:Arabic words and phrases Category:Pollination management Category:Substances used in homeopathy
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