Last updated on February 23, 2014  

Note: This information was developed from lecture notes for the Farm and Industry Short Course at the University of Wisconsin.


Soybean first entered North America in the 18th century.  Soybean first entered North America in the 18th century. 

It was not until the 1930s that the crop started to be processed industrially for edible oil and protein meal in the United States. 

Since that time it has become the most widely grown protein/oilseed crop in the world, with both North and South America producing large portions of the world's supply of this remarkable crop.

Soybean taxonomy: Glycine max L. Merrill

Glycine ussuriensis = wild type

  • Progenitor of cultivated type
  • Grows wild in se asia.
  • Both types are diploids 2n=40
  • Early uses of soybeans
  • Grown in the orient for centuries

Uses: human food, animal feed, industrial purposes, fertilizer

Oil crop and protein crop = 18-20% oil and 38-40% protein

Soybean meal = 44% protein and 1% oil

World acreage and production

USA 45% of acreage,  55% production

China 25% of acreage, 15% production

Brazil and Argentina  big in soybeans during past 20 yrs  they have deep, fertile soils and favorable climate

Development of soybeans in U.S.

In U.S., principal early use was as a forage crop

  • Hay or silage grown with millet or sorghum for hay
  • Grown with corn to enhance silage quality and to supply N to corn

1915 first oil extraction in U.S. mills

1930 25% of the U.S. crop was crushed

1941 soybean acreage grown for seed first exceeded acreage grown for forage

1920 to 1979 continual increase in soybean acreage

1980 to 1988 acreage has dropped to some extent, especially since 1985 (farm bill)

1986 to 1988 average U.S. crop acreages

  • Corn 62 million/yr
  • Wheat 47 million/yr
  • Soybeans 57 million/yr

U.S. soybean acreage

  • Early production concentrated in SE U.S.
  • By mid 1920's, were popular in Midwest
  • In 1924, Illinois became the leading soybean state (acreage) in the U.S., and has been the leader since that time
  • Leading states "corn belt" states and se states
  • Illinois and Iowa: 89 million acres/yr usually produce about 1/3 on about ¼ of the U.S. soybean acres
  • Missouri, Indiana, Minnesota, Arkansas 35 million acres/yr

Why did soybean acreage increase so steadily between 1915 and 1979?

  • Boll weevil made cotton scarce in the 1920's and 1930's; needed another crop in the south
  • When farm power switched from horses to tractors, not as much oats and hay were needed
  • Price supports and lack of acreage restrictions
  • Traditionally, the U.S. exports at least ½ of its annual soybean production  Japan, W. Europe, Arabic countries, USSR

Keys to Increased Yield & Profitability

Pointers for High Yields

Yield produced by the soybean plant depends upon the rate and length of time of dry weight accumulation. To produce high yields, therefore, use cultural practices that are consistent with good economics to maximize the rate and length of time of dry weight accumulation in the grain.

Management practices to consider:

  1. Fertilize and lime based on a sound soil testing program.
  2. Do not till or plant when soils are too wet.
  3. Plant on dates recommended for your area.
  4. Select varieties best suited to your area.
  5. Maximum productivity is achieved at closer row spacings than traditional 30- or 40-inch rows.
  6. Use optimum plant populations for your row spacing.
  7. Don't plant too deep-1.5 to 3.8 cm (1 to 1l/2 inches) is optimum in most soils.
  8. Monitor and control pest (weed, insect, etc.) populations as needed.
  9. Keep harvest losses to a minimum.


Yield enhancement due to crop rotation is not limited to corn.Wisconsin studies indicate that the yields of other crops in the rotation also benefit 10 to 25% when grown following other species, compared to continuous cropping.  Soybeans are particularly rotation sensitive; in individual years, first-year soybean yields after corn have been increased nearly 50% compared to yields after several years of continuous soybeans.

List of publications agronomists should have in their library:

  1. Modern Corn and Soybean Production by Hoeft, Nafziger, Johnson, and Aldrich

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