Mike Larson, Peterson Farms Seed sales manager, blew through the 400-bushel-per-acre yield mark last year in a maximum yield test plot he conducted at Harwood, N.D.

Larson produced more than 400 bushels per acre, not once, but three times with three different hybrids.

It was pretty exciting, Larson says.

Mike Larson

The genetic yield potential of corn is estimated to be about 600 bushels per acre. National Corn Grower Yield contest winners have been pushing 500 bushels per acre in recent years. In South Dakota, farmers are approaching 300 bushels per acre in the contest. In North Dakota, where just a few years ago 150-bushel corn was good and 200 bushels was amazing, a 400-bushel yield seemed impossible.

Beginning in 2013, Larson set out to find out if 400 bushels was really out of reach.

He hand-planted corn in an 8-by-12-foot plot using a planter grid made out of a sheet of plywood. He called it the “High-Tech Caveman 2.1 Equi-distance Planter.”

He built an irrigating/fertilizing system from PVC pipe and a 30-gallon poly drum so he could spoon-feed the corn plants water and fertilizer.

He applied a standard corn seed treatment and hand-weeded the plot. He didn’t use any fungicides, soil amendments or fertilizer additives.

Yields steadily crept up — 356, 377, 389 — as he tweaked the population, plant spacing and fertilizer rates.

2016 strategy
Here’s what he did in 2016:

• Fertilized for 200-bushel corn.

• Planted on May 1 in a diamond-shaped pattern with each plant getting 1 square foot of space. The final stand was 43,560 plants per acre. “In the past, we used a square-shaped pattern but quickly realized that we could utilize the space more with the diamond-shaped pattern,” Larson says. “The changes that come from comparing year-to-year results show the importance of being flexible and open-minded in your approach to yield.”

• Added extra fertilizer. He spread 300 units of ammonium sulfate June 10. During the week of July 4, two of the seed company’s interns “spoon-fed” the plot (via PVC pipe and a 30-gallon poly drum) with 40 units of N and 40 units of potash in a liquid slurry that added what would equal a half inch of water. They continued the spoon-feeding every Monday until Aug. 15. “Up until this year, this would have ended the spoon-feeding schedule, but … enter the first-ever fall intern who continued the same protocol for three additional weeks,” Larson says.

Results
Larson and others and Peterson Farms Seed harvested and shelled the corn by hand and calculated the yield based on 14.5% moisture.

Three Peterson Farms Seed hybrids went over 400 bushels per acre.
• 86S98SS — 406 bushels per acre
• 76S92VT2 Pro — 432 bushels per acre
• 81W01SS — 435 bushels per acre

2016 was a very good year for corn in much of North Dakota and South Dakota, of course. The weather was perfect. There were a lot of sunny days. The temperature was just right. There were no problems with emergence or plant spacing.

Larson figured what got the plot over the 400-bushel mark was the extra fertilizer after Aug. 15. “It increased the test weight 15%, and yield is kernel number times kernel weight,” he says.

There was even more yield potential in the plot than was harvested. In some hybrids, green snap took out about 10% of the plants. The loss seemed to be related to when the fertilizer was applied.

“It’s been exciting to see what corn can do,” Larson says.

He plans to continue the project. Now, he is shooting for 500 bushels.

Extra fertilizer, seed paid off

To raise 435-bushel corn Mike Larson figured it cost an extra $314.54 per acre.

Compared to seeding and fertilizing for 200-bushel corn, the extra costs were:
• 400 units of N at $136.75 per acre
• 400 U of K at $100 per acre
• 300 pounds of 21-0-0-24 at $46.50 per acre
• 9,560 additional plants at $31.29 per acre

At a $3-per-bushel market price for corn, net income was $390.46 per acre higher for the corn that yielded 435 bushels per acre than the corn that yielded 200 bushels.