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10 ways to de-stress corn
Not many corn farmers will miss the past two growing seasons. In 2011, the season was very wet early, very dry late, and extreme wind, hail, and heat in between. This year started out great, with timely planting occurring and ample early-season moisture.
Then the worm turned in June. Relentless drought and heat continued throughout the summer. The result was the worst drought since 1988. At presstime, USDA yield estimates hovered around 123 bushels per acre. That's well below 2011's 147 bushel per acre average, and 2010's 152.8 bushel per acre level.
While corn farmers everywhere wish for a year with no crop stress, recent years should teach that this will not happen. If anything, weather experts say there will be even more weather extremes and crop stress.
“It's the norm now, and we can get used to it,” says Bob Nielsen, Purdue University Extension agronomist.
There is some good news. “None of those stressors alone ends up being the kiss of death to a corn crop,” Nielsen continues. “We can work around them, and the crop can recover.
Your challenge is to identify the other yield-limiting factors – the ones you can control – and de-stress those things. Then you'll be in a better position to handle the unpredictability of a growing season.” Here is Nielsen's 10-point checklist for stress-proofing your corn.
1. Improve field drainage
This reduces several risks over the course of a growing season: field ponding, compaction, cloddy seedbeds, nitrogen loss, and poor root development. “Young corn plants do not like soggy soils, and nobody seems to be working on corn hybrids that do,” says Nielsen. “And besides that, soil nitrate-nitrogen disappears by leaching or denitrification when soils are saturated. We see it over and over: Good tile drainage pays.”
2. Conserve soil moisture and minimize soil erosion
While this can seem counter to point number 1, it's not. Some fields are simply better drained or are subject to erosion because of topography. Practices such as using reduced- or no-till, terracing fields, and planting cover crops will conserve surface moisture and carry a crop through a dry stress, particularly early when roots are shallow. In 2011, that late-season heat in the mid-90°F. was not particularly stressful to corn if it had moisture that it could access, says Nielsen.
3. Identify corn hybrids that best tolerate your stressors
“I encourage you to be very involved in the hybrid selection process. Don't simply let your seed dealer tell you what to plant,” says Nielsen. “You're the one who has to pay for it and live with the outcomes, so trust yourself first.”
This also includes managing the technology package in your hybrids. “For instance, we know that corn rootworm is wonderfully adept at overcoming our control strategies,” he says. “So don't rely on one control mechanism or even one Bt event in your hybrid choices.”
Some farmers make the mistake of only evaluating hybrid trial results close to home. “You don't know what stressors you're going to have this year,” he says. “It may be something that was experienced far away last year,” he says. “Look for hybrids that are consistently in the upper 10% of yield trials in a variety of locations and conditions.”
4. Manage residue
You need to provide the best possible seedbed, and no-till conditions in particular can make that difficult.
“Use trash cleaners on the planter, kill any winter annual weeds out there, and then plant on the dry side of conditions if at all possible,” says Nielsen. “If you can get that perfect seedbed, even late planting is not a yield breaker, he says. “We were three weeks late in 2011; some fields weren't worked until June. But with warm soils in June, we got a fast emergence, and silking was only one to two weeks delayed. The crop has a tendency to catch up.”
5. Don't compact soils
This is a season-long process of minimizing trips when soils are wet. And it even includes harvest traffic, especially loaded grain carts. If it's a wet harvest season, practice controlled traffic in designated lanes.
Compacted soil reduces the size and depth of corn roots, says Nielsen. Those plants are much more easily flattened by strong winds, which happened in many areas last summer.
Still, he says, he was amazed at the ability of down corn to gooseneck back up, in some cases as far as 30 inches to the side. “If it is flattened one to two weeks before pollination, it has time to gooseneck and recover and then pollinate normally,” he says.
6. Avoid continuous corn
“I don't like it, especially no-till continuous corn,” says Nielsen. “It delays soil drying in the spring, it harbors diseases and other pests, it immobilizes soil nitrogen, and it intercepts herbicides. I have trouble thinking of much good from continuous corn.”
7. Use a starter fertilizer program
This is especially true if you have a plan for starter nitrogen.
“In challenging, stressful conditions, this really pays,” says Nielsen. “Up to about knee-high, when the temperatures are still cool and it's wet, starter N helps a lot by getting the crop through that phase when it sometimes stalls out and turns yellow. Starter fertilizer gets a good, robust stand going early. I like to put on about 30 pounds (per acre) of starter nitrogen.”
8. Minimize nitrogen losses
Don't apply nitrogen in the fall, Nielsen says, and make sure you incorporate urea-base fertilizers because they are subject to volatilization.
“Sidedress into the growing crop where that is practical,” he recommends.
9. Manage diseases
Diseases can rob 20% or more of yield and make the plant less tolerant of other stresses.
“Use crop rotation to break disease cycles, and selectively use tillage to bury corn stover,” says Nielsen. “Foliar fungicides can have a role in this, too.
“Also, choose corn hybrids that show excellent disease resistance to gray leaf spot, northern leaf blight, and Goss's wilt.” Goss's wilt is spreading eastward, he says, and it's a scary threat. “It loves continuous corn,” he says.
10. Walk your fields
“The first 30 to 45 days are critical. That's when the crop is getting up to about knee-high,” points out Nielsen. “I don't think people walk their fields enough in that time, looking for early indications of problems or stress. Then walk them in July and August and look at the root health of the corn. Good observation is one of the best things you can do to de-stress your crop.”