If you find yourself wishing for a normal corn-growing season this year, Bob Nielsen has bad news.
“I think we actually need to redefine normal weather,” the longtime Purdue corn agronomist said. “Today, normal weather consists of an unpredictable number of unpredictable extreme weather events, each occurring unpredictably with unpredictable severity.”
Corn growers need to focus their energy on weatherproofing their fields, Nielsen told growers during Purdue’s virtual Crop Management Workshop held Jan. 28.
“When we get extreme weather, the negative effects of it are often amplified by other yield-limiting factors that may exist in the field,” he explained. Those include problems such as poor drainage and compaction, which can make a heavy rainfall or a flash drought more damaging than they need to be.
“While we cannot control the weather, if we can identify and manage these other yield-limiting factors in the field, this will help us improve the overall resilience of crops to the vagaries of Mother Nature,” Nielsen said. In his talk, Nielsen outlined how to avoid the 10 biggest obstacles that can prevent a cornfield from emerging, developing and finishing in uniform good health.
1. IMPROVE SOIL DRAINAGE
So much of the potential damage from extreme weather — ponding, flooding, nitrogen loss, compaction, messy seedbeds and delayed fieldwork — have their source in poorly drained soils, Nielsen stressed.
“It simply makes the effects of excessive rainfall so much more dramatic,” he said.
Whether it’s old tile that needs to be replaced, or a field that is naturally poor at draining, improving soil drainage should be a top priority in weatherproofing your crops, he said.
2. MINIMIZE SOIL EROSION
Eroded fields and poor soil structure are a serious problem in many cornfields, especially in hilly topographies, Nielsen noted. Assess your land, field by field, and figure out how you can keep soil in place and improve its health, whether with no-till, reduced till, contour farming, strip cropping, terraces or cover crops, he advised.
3. PERFECT YOUR IRRIGATION PRACTICES
Growers with irrigation options have a leg up on dryland farmers — but only if they manage their water use carefully, Nielsen said. Make sure your irrigation equipment is efficient and in good condition. Avoid excessive soil moisture early during stand establishment and falling behind on the crop’s water needs later, he said.
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“If we can maintain adequate soil moisture in the field all the way to kernel black layer, that will help achieve maximum grainfill and maximum kernel weight and get us to maximum yield,” he said.
4. PICK HARDY HYBRIDS
“Stress tolerance in hybrids plays a huge role in determining the resilience of a crop,” Nielsen said. Don’t just look for high-yielding hybrids — look for the ones that yield in the top of trials consistently across a wide variety of trial locations and geographies, he advised.
“The reason I emphasize the need to get as many variety trials as we can get our hands on is because that tends to represent a range of possible growing conditions that we might experience in years to come on our own farms,” he said. For high stress tolerance, look for hybrids that show good early season vigor, heat or drought tolerance, disease resistance and root and stalk strength.
5. MANAGE YOUR RESIDUE
No-till, minimum till and cover crop practices can play a significant role in weatherproofing crops, but they come with, well, a little trash.
Leftover corn stover and cover crop residue need to be managed carefully to avoid slow-warming soils and poor soil-to-seed contact during planting, Nielsen warned. Have a plan for timely cover crop termination, use planter row cleaners ahead of disk openers and avoid planting into wet soils whenever possible, he advised.
6. MINIMIZE SOIL COMPACTION
Soil compaction can make just about every bad weather event worse, Nielsen explained. Saturated soils stay saturated longer, and moisture-seeking roots get restricted to shallow depths.
He recommends avoiding tillage or field traffic when soils are “on the wet side or simply not fit to be on.” That might mean rethinking your tillage practices, from reducing tillage trips across the field to switching to strip till or no-till to eliminate them. As much as possible, try also to minimize traffic from grain carts and other heavy equipment, Nielsen added.
7. AVOID CONTINUOUS CORN
Crop rotation doesn’t just help with disease and pest management — it can be a boon to your seedbed prep and soil health, Nielsen noted. Particularly in no-till situations, an abundance of corn stover and root balls can delay soil drying and warming, interfere with planting and soil herbicide applications, slow emergence and tie up nitrogen as it decomposes, he warned.
And, of course, corn residue provides a convenient home to overwintering disease inoculum, which can build up quickly in continuous corn fields.
8. IMPROVE NITROGEN UTILIZATION
The simplest way to make sure you don’t waste a drop of nitrogen in a cornfield is to move your applications as close to the time that the corn plant needs them as possible.
That means moving away from fall nitrogen applications and away from surface-applied urea-based fertilizers without incorporation, Nielsen said. “Sidedressing nitrogen where practical is still the most efficient timing of nitrogen application,” he said.
Years of research with Purdue soil fertility specialist Jim Camberato have persuaded Nielsen that starter fertilizer is also a good investment, particularly 2-by-2 row starter applications of at least 30 pounds of actual nitrogen.
“It aids the early transition from the young plants from reliance on kernel reserves and seed roots to increasing reliance on the primary root system, called the nodal root system,” he explained. “This transition occurs around V3 and ends about V6.”
The availability of that concentrated band of nutrients is especially important to young plants if environmental conditions at the time of that transition aren’t favorable for vigorous, rapid growth, Nielsen said.
9. REDUCE DISEASE POTENTIAL
Disease not only steals yield, but it also weakens plants and leaves them more vulnerable to other stresses, such as heat or wind.
Learn what diseases your fields have a history of and manage them appropriately, whether with genetic tolerance in your hybrids, crop rotation, tillage or residue management and the judicious use of in-season foliar fungicides, Nielsen said.
10. KILL YOUR WEEDS
Weeds rob sunlight, nutrients and water from your crop, and they are increasingly resistant to a variety of chemicals. Growers need to know their field’s weed history and resistance background, and have a plan of attack each year, Nielsen said.
“Consult the weed science experts at the various land-grant universities in your region and kill ’em when they’re small!” he urged.
Emily Unglesbee can be reached at Emily.email@example.com
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