An erect, bushy annual legume grown worldwide for its protein- and oil-rich seeds.
The soya bean (Glycine max, family Fabaceae) is an upright, much-branched annual 20 to 200 cm tall, sometimes with twining stems. Its branched taproot goes down 2 metres, with side roots spreading up to 2.5 metres in the top 20 cm of soil. It is one of the world's major foods, giving high-quality protein and an edible oil, and one of the most widely grown crops, cultivated since about the 11th century BC. It is also used in traditional medicine, its oil has many industrial uses, and it is grown as green manure. The raw mature seed contains several harmful substances, which soaking and long cooking, sprouting, fermenting (as in miso and tempeh) or roasting make safe.
It originated in East Asia and has spread through cultivation from the tropics to latitude 52°N. It grows best at 20 to 32°C with 600 to 1,500 mm of rain a year, and it does not do well in a wet climate or in extreme heat or cold. It prefers sun and fertile, well-drained, slightly acid soil, but its deep roots let it do better than many crops on poor, droughty or badly drained soils. It flowers 25 to 150 days after germination, depending on day length, temperature and variety, and a crop takes 10 to 28 weeks. Average yields are about 1,700 kg per hectare, and good varieties can give more than twice that.
Source: Useful Tropical Plants database (Fern, K.).
Seeds are processed into oil, flour, milk, and various fermented and unfermented foods; a major source of dietary protein and cooking oil.
Grown as a rotation and cash crop; fixes nitrogen in the soil through root nodules and matures in about 3-4 months.