The first written record of soybean was found in Chinese books that included plants of China described by Emperor Cheng-Nung in 2838 B.C. The exact origin and early history before this date is unknown. Soybean has been repeatedly mentioned in later records as a most-important cultivated legume crop throughout Asia and particularly in China. The soybean was first domesticated in the eastern half of north China in the 11th century B.C. The cultivated form of soybean was introduced into Korea from North China and into Japan between 200 B.C. and 300 A.D. Even today the soybean provides a very important protein source in the diets of many Asian nations.

The soybean has also been used and is used for soy sauce, soy milk, soy curd, soy paste, and bean sprouts. Currently many forms of these same products are being modernized to appeal to Americans and their low calorie diets. The principal early use of soybean in the United States was as a forage crop. The crop was frequently harvested for a single crop of hay or plowed under as a green manure crop to improve the soil structure and fertility. Soybean as a forage crop may now be reintroduced as a relatively new option for dairy farmers because new varieties have recently been developed by the USDA for forage soybean. These soybeans are late maturing gerrnplasm that will grow five to six feet tall with a large physical structure and produce very few seeds because flowering occurs late in the season. The intent is to use these forage soybean varieties for silage mixed with corn silage, thereby improving the overall nutrition of the silage. These forage varieties have not yet been released for commercial use but are being studied throughout the Midwest. Soybean may be grown alone as we frequently find them in the soybean belt of the United States or they may be grown with other crops as forage crops or grain crops. The intercropping for grain crops usually occurs in those areas of the world where hand labor is used for planting and harvesting to keep the grain from different crops separate.