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Get on road to 250-bushel corn crop

The road to 250-bushel corn starts with getting your next 20 to 25 bushels per acre, according to John McGillicuddy, a 30-year veteran agronomist from Iowa City, Iowa, who consults with corn growers from Texas to the Dakotas on how to increase yields. He spoke at Peterson Farms Seeds field day near Harwood, N.D., in August. McGillicuddy boiled down his formula for producing more corn to the basics. “Yield equals the number of kernels times the kernel weight,” he said.

Generally, 75,000 to 90,000 kernels equal a bushel of corn — 56 pounds. Therefore, the first step to a 250-bushel-per-acre average yield is to calculate how many kernels from your crop it takes to equal 56 pounds.

Buy an electronic scale (you can find one for about $100 at most office supply stores), count out 250 kernels and weigh them. Then, project the number kernels it will take to weigh 56 pounds.

If it takes 75,000 to 90,000 kernels to equal 56 pounds, kernel weight is in the normal range, McGillicuddy said.

If it takes a more than 90,000 kernels to reach 56 pounds, you need to determine why your kernels are lighter than normal, and if there’s anything you can do about it. Kernel weight is largely determined late in the year, usually by the weather, and/or late-season plant health.

Producing heavier kernels may mean planting earlier, planting hybrids that mature earlier, or doing both.

Step 2

The other half of the yield equation — kernel number — is something that you have more control over. The number of kernels produced per acre is a function of the girth and length of the ears, the number of plants per acre and the number of ears per acre.

Girth is a function of plant breeding. Whether the plant is able to fill out the ear depends on the weather, soil conditions and available nutrients in the soil.

A clue to whether you have reached maximum yield potential is at the kernel tip. If the ear is large and is filled all the way to the end, you probably wasted resources. If there’s about ¾ inch of tipback at the end of the year, the plant used all the resources available, McGillicuddy said.

Plant population

The ideal plant population varies by region and is constantly changing with new varieties and practices. But whatever level is ideal for your farm, the number of ears per acre should be within 1,000 to 1,500 of the number of plants per acre.

“If it’s not, you have to figure out why,” McGillicuddy said.

There could be too many skips or doubles in the field. Skips could be an equipment problem. It could also result from poor seedbed preparation, poor germination or excessive planter speed.

Another problem is doubles. One or all of the plants growing too close together may be barren. Planter speed and equipment problems are the main cause of doubles.

Fertilizer mistakes

Not having enough fertilizer to fully develop and fill out ears is another problem. Often, adequate fertilizer isn’t available at the time corn plants need it.

“It’s a bigger challenge the earlier you plant, or if the weather cools off after emergence,” he said. Corn establishes its maximum yield potential from emergence to the V12 stage of growth. If a plant runs short of nutrition in the first weeks of growth, yield potential will be reduced, he said.

Placing the correct fertilizers with the seed or in a 2-by-2 placement next to the seed are possible ways to provide good early nutrition. “The goal is to provide adequate plant nutrition for the seedling the first day,” he said.

Detective skills

To get on the road to 250-bushel-per-acre corn yields “you need to be a good detective,” McGillicuddy said.

You can’t afford to buy all the possible solutions — better hybrids, a new planter, more fertilizer, different tillage tools, etc. You have to narrow it down. “There’s no substitution for doing homework in your own fields,” he said.


CORN SLeuTH: Consultant John McGillicuddy, a 30-year veteran agronomist, looks to the corn plant to find clues to what’s holding back yields.

This article published in the January, 2010 edition of DAKOTA FARMER.

All rights reserved. Copyright Farm Progress Cos. 2010.