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From 23 bushels per acre to 300? It's possible

By Janet Kubat Willette

Date Modified: 08/26/2010 9:11 AM

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GILFILLAN, Minn. — Back in 1866, Minnesota farmers grew open pollinated corn that yielded about 23 bushels to the acre.

Could the state's farmers produce 300 bushels to the acre in 2030?

University of Minnesota Extension corn agronomist Jeff Coulter crunched the numbers and showed a chart he created at Farmfest.

From 1866 to the 1930s, farmers grew open pollinated corn, picked the corn by hand and saved the best ears for shucking and planting the kernels the following year, Coulter said. Yields showed a .1 bushel per acre per year rate of improvement for that period, with the variability in yields from year-to-year greater than the growth in yields, he said.

State average yields varied from a low of 18.5 bushels per acre in 1894 to a high of 38.5 bushels per acre in 1921. Variability from year-to-year was great, with 26.5 bushels per acre in 1877 rising to 36.5 bushels per acre a year later and 35 bushels in 1914 falling to 23 bushels a year later.

Open pollinated corn was more irregular than today's uniform rows of green stalks, said Vernon Cardwell, Morse Alumni Distinguished Teaching Professor of agronomy and plant genetics, who joined Coulter in the University of Minnesota tent. Also, tassel colors differed.

The stalks were of varied heights, but usually taller than today's hybrids. Up through the 1970s, stalk height averaged 10 feet and some were as tall as 14 feet, Cardwell said. Today's stalks average about eight feet in height.

The taller stalks were more convenient for hand picking, which continued in the state up through the 1950s.

The first corn hybrids were developed in 1892, Cardwell said, but commercialization didn't begin until 1932-1933.

A double-cross hybrid with four parents was marketed in the 1930s through 1950s and in the 1960s, a triple cross of three parents entered the market. The triple cross had more hybrid vigor. In the late 60s, the single cross of today's genetics was introduced. Hybrids were selected for inbred lines with high yields.

In the double cross era of 1933 to the 1960s, corn yields grew by an average of 1 bushel per acre per year, Cardwell said. In the single cross era that began in 1970, yields increased by two bushels per acre per year, for an average of 1.5 bushels per acre for the hybrid era from the 1930s to the 1990s.

The transgenic era started in 1997-98, Cardwell said.

In the 12 to 13 years since, yields have grown by an average of 2.4 bushels per acre per year, Coulter said. At that rate of increase, state average yields will grow to 234 bushels per acre in 2030, he said.

To reach the state average yield of 300 bushels per acre in 2030 that some have suggested is possible, yields would have to grow six bushels per acre per year, Coulter said.

Isolated fields are already bumping up against 300 bushels. Coulter said a field near Sleepy Eye yielded 268 bushels per acre last year and there are fields that could produce 300 bushel corn this year if the weather holds.

Generally, corn yields are higher in southern Minnesota than northern Minnesota, which is a function of the growing system length, Coulter said.

Minnesota's farmers generally grow around 7 million acres of corn each year. USDA is predicting a state average yield of 178 for 2010.