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the web of life in southern Africa

Glycine max (Soybean)

Life > eukaryotes > Archaeoplastida > Chloroplastida > Charophyta > Streptophytina > Plantae (land plants) > Tracheophyta (vascular plants) > Euphyllophyta > Lignophyta (woody plants) > Spermatophyta (seed plants) > Angiospermae (flowering plants) > Eudicotyledons > Core Eudicots > Rosids > Eurosid I > Fabales > Family: Fabaceae > Subfamily: Papilionoideae

Domesticated in northeastern China from the wild Glycine soja, the earliest evidence of cultivation dating to 3000 years ago.

The cultigen species Glycine max, known as Soybean, was domesticated in northeastern China from the wild Glycine soja, the earliest evidence of cultivation dating back to 1000 BC. In the third century BC, Soybean and Millet were regarded as the most important food crops in northeastern China. Soybean remains an important source of high protein to people in the Far East and Southeast Asia. From the 1700's, European visitors to the Far East started bringing back Soybean seed to Europe and introducing it to the colonies. Soybean started being grown in the USA from 1765 onwards but it was only in World War II with butter shortages and the need for substitutes that the soybean crops really took off and by 1973, the USA was producing three-quarters of the world crop. Maize farmers found that rotating maize with soybeans reduced the need for nitrogen fertilizers because, being legumes, Soybean have Rhizobium bacteria in their roots that convert gaseous nitrogen to nitrogenous compounds.

Like most plants that have been domesticated, Soybean is mainly self-pollinating which means that people have been able to easily keep separate breeding lines. This has resulted in a large number of different cultivars, differing for instance in seed colour. Domesticated Soybean differs from wild forms in the following chacteristics:

  • plants are taller and more erect;
  • pods do not shatter their seeds early so seeds are not lost before harvest;
  • seeds are larger;
  • seeds have a higher oil content;
  • seeds are more flavoursome;
  • seeds are quicker cooking; and
  • digestibility is greater although there are still problems with digestibility because seeds contain tryptophan inhibitors that lower the availability of amino acids in the seed. These inhibitors can be deactivated through cooking, although overcooking reduces protein quality.

Soybeans are used in a variety of ways in Asia:

  • they are eaten as grean beans and as bean sprouts;
  • mature seeds are treated in a variety of ways including cooking whole seeds, milling or liquefying them;
  • they can be made into milk, often used by people allergic to dairy products;
  • tofu or soybean curd, has a cheese-like consistancy and a rather bland taste and can be eaten on its own or used in combination with other foods; and
  • Indonesian tempeh, Japanese miso and the well known soy sauce are soybean products produced through ferementation using fungal and/or bacterial cultures.

In the west, soybean oil is used for producing various products including margarine, salad oil and soap. The residual cake from pressing out the oil is a valuable high protein feed for livestock. It is not often realised how much soybean is used directly in everyday food products and indirectly through being fed to livestock.

Ecological interactions

Not covered here other than to mention Phakopsora pachyrhizi (Asian soybean rust), which has infected soybean crops in South Africa since 2001.


  • Sauer, J.D. 1993. Historical geography of crop plants - a select roster. CRC Press, Boca Raton, Florida.

Text by Hamish Robertson