ashvakshura :

Geographical distribution:

During the early 2000s, alfalfa was the most cultivated forage legume in the world.^[59] Worldwide production was around 436 million tons in 2006.^[59] In 2009, alfalfa was grown on approximately 30 million hectares (74,000,000 acres) worldwide; of this North America produced 41% (11.9 million hectares; 29,000,000 acres), Europe produced 25% (7.12 million hectares; 17,600,000 acres), South America produced 23% (7 million hectares; 17,000,000 acres), Asia produced 8% (2.23 million hectares; 5,500,000 acres), and Africa and Oceania produced the remainder.^[60] The US was the largest alfalfa producer in the world by area in 2009, with 9 million hectares (22,000,000 acres), but considerable production area is found in Argentina (6.9 million hectares; 17,000,000 acres), Canada (2 million hectares; 4,900,000 acres), Russia (1.8 million hectares; 4,400,000 acres), Italy (1.3 million hectares; 3,200,000 acres), and China (1.3 million hectares; 3,200,000 acres)

ECOLOGICAL ASPECT:

Alfalfa is a perennial forage legume which normally lives four to eight years, but can live more than 20 years, depending on variety and climate.[13] The plant grows to a height of up to 1 m (3.3 ft), and has a deep root system, sometimes growing to a depth of more than 15 m (49 ft) to reach groundwater. Typically the root system grows to a depth of 2–3 metres depending on subsoil constraints.[13] Owing to deep root system, it helps to improve soil nitrogen fertility and protect from soil erosion.[14] This depth of root system, and perenniality of crowns that store carbohydrates as an energy reserve, make it very resilient, especially to droughts. Alfalfa is more drought-hardy than drought-tolerant and the persistence of the plant also depends on the management of the stand.[13] It has a tetraploid genome.[15]

Alfalfa is a small-seeded crop, and has a slowly growing seedling, but after several months of establishment, forms a tough "crown" at the top of the root system. This crown contains shoot buds that enable alfalfa to regrow many times after being grazed or harvested; however, overgrazing of the buds will reduce the new leaves on offer to the grazing animal.

This plant exhibits autotoxicity, which means it is difficult for alfalfa seed to grow in existing stands of alfalfa.[16] Therefore, alfalfa fields are recommended to be rotated with other species (for example, corn or wheat) before reseeding.[17]