Corn Production in Minnesota, 1866–2016

The story of the transformation of Minnesota’s landscape from the earliest European immigration to the twenty-first century is a story about corn. Although the yearly increments of change in production practices and yield were small, their aggregate impact was astounding. They can be broken into three major phases: mechanical, chemical, and biological.

Indigenous people, including the Dakota and Ojibwe, grew corn in present-day Minnesota before the arrival of the first European immigrants. In the 1800s, two major events encouraged these immigrants to move to the region to grow corn and other crops. First, the introduction of the steel moldboard plow, developed by John Deere in 1837, permitted the breaking of the dense prairie sod. Second, the passage of the Land Grant Act of 1862 provided access to cheap land.

During this period, farmers cultivated one row of corn at a time, by hand. Check-row planting allowed them to cultivate both parallel and perpendicular to the row. To achieve check rows, they planted corn in hills with three or four plants per hill, and with equidistant spacing of hills in the row and between the rows. It saved labor to plant three or four seeds in spaced hills instead of separating holes for each seed. Planting in hills also reduced lodging (stalk breakage from wind damage), to which early varieties of corn were susceptible. It also made hand harvesting easier.

Mechanical planters were developed in 1834 but were not widely used until after the Civil War. Farmers continued to prefer the hill-planting method for purposes of cultivation, reduced stalk breakage, and ease in hand picking. Mechanical planters were adapted to drop seeds within rows at spacings of fifteen to twenty inches between hills. Although this eliminated the opportunity to cross cultivate, it provided better stand ability than was achieved by drilling (dropping single seeds). Hybrids and improved plant-stalk strength allowed corn to be “drilled” as single seeds by the late 1980s.

Plant density (the number of plants per acre) remained low as long as farmers picked corn by hand. One big ear was easier to pick than several small ears. The advent of hybrid corn (with stronger stalks) and of mechanical pickers favored higher plant densities. The improvement in yield is in part a reflection of the ability of modern hybrids to produce good ears on every plant, even as plant populations have increased to over 30,000 plants per acre. The number of plants per acre has almost tripled since the 1800s.

Plant nutrients were initially provided by the mineralization (breakdown) of organic soil matter. The virgin prairie soils averaged 8 to 10 percent. Plowing aerated the soil, allowing micro-organisms to release about twenty pounds of nitrogen per percent organic matter in the soil. Soil fertility was, in part, sustained by a crop rotation of wheat, oats, barley, flax, and hay crops. Oats, barley, and hay crops provided feed for draft animals.

After World War II, large quantities of manufactured nitrogen, used in making explosives for the war, became available for farm use. The depleted soils and the new corn hybrids responded well to the manufactured nitrogen. The use of manufactured nitrogen for crop production expanded rapidly in the 1970s and 1980s. Fertilizer use leveled off after the 1980s, however, due to environmental concerns.

Time and method of application and the forms of the fertilizer applied increased fertilize use efficiency. Breeding for greater uptake and use by corn plants allowed yields to double from 85 bushels per acre (Bu/A) with ninety-eight pounds nitrogen per acre (N/A) in the 1970s to 170 Bu/A with 125 pounds N/A in the 2010s.

During World War II, scientists had also developed herbicides to control weeds in growing crops. In 1946 the herbicide called “2,4D” (2,4-Dicholorophenoxyacetic acid), was the first of its kind available to farmers to kill broadleaf weeds in a grass crop like corn. Another chemical, atrazine (1,3,5-Triazine), became available in 1959. Atrazine controlled broadleaf weeds as well as many common grass-type weeds in corn.

After more than fifty years of use, both chemicals still rank among the top corn herbicides. The development of Roundup Ready corn in 1998 made Roundup (glyphosate) the chemical most commonly applied to corn. Roundup effectively controls most common grass and broadleaf weeds as well as volunteer crops at many stages of growth, without injury to corn. Chemical weed control has changed the frequency of mechanical cultivation from three or four times a season to less than one, with many acres receiving no row cultivation. This method saves time, labor, fuel, and soil.

Corn had no major insect pests until the European corn borer was introduced into the United States in 1917. It reached Minnesota in the 1940s and by 1948 had spread throughout the entire corn-producing area. Early control efforts focused on burning, shredding, and chopping the stalks as well as plowing during the fall, which buried overwintering larva. As of 2016, annual losses since 1950 are estimated to be 3.5 to 6 Bu/A /year, or about 5 percent annually, even with insecticides.

Another insect, the corn root worm (Diabrotica speciosa), is endemic to Minnesota. Losses occur primarily when corn follows corn in the crop rotation cycle as the adult lays its eggs at the base of tasseled corn plants. The eggs hatch only when stimulated by new corn roots the next year. Losses in fields of corn-after-corn averaged up to 7 percent, or about 11 Bu/A. Most of the yield gain in 1996 was due to the planting of Bt corn—a genetically modified organism (GMO) designed to improve pest tolerance.

The era of genetics and biotechnology began in the 1870s with research on inbred lines of corn and the recognition that progeny had “hybrid vigor” when crossed. It took until the 1930s to develop a system of seed production called “double crossing” to make seed affordable for farmers. This involved four different inbreds. Inbred A was crossed with B to give single cross, AB. Inbreds C and D were crossed to give a single cross, CD. The single crosses, AB and CD, were crossed to produce a double cross, AB X CD. This development gave rise to our modern seed industry.

Minnesota farmers began planting hybrids in the 1920s, and by the mid-1940s, over 80 percent of the corn acreage was planted to hybrids. The average corn yield of the 1940s was 134 percent of the previous decade. Multiple factors contributed to this increase, including the drought of the 1930s. But most research indicates that half of the gain in yield was due to hybrid vigor and improved genetics over the older, open-pollinated varieties.

By 1970, virtually all of Minnesota’s corn acreage was planted to hybrids. Improved hybrids, coupled with earlier planting, more fertilizers, herbicides, insecticides, narrower rows, and higher plant densities, boosted state corn yields to 107 Bu/A in the 1980s.

Since 1955, annual yield gains have exceeded 1.5 Bu/A, with an increase in corn acreage of 138 percent. Minnesota corn yields have increased by 368 percent to date (2016). The total amount of corn produced in Minnesota has increased from 299.3 million bushels to 1.54 billion bushels—a 440.4 percent increase.

Annual yield gains have exceeded 1.5 Bu/A/year over the last fifty years, with an increase in corn acreage of 138 percent. For a person born in 1955, the Minnesota corn yields have increased by 368 percent to date (2016). The total amount of corn produced in Minnesota has increased from 299.3 million bushels to 1520 million bushels—a 508 percent increase.