This time of year, Ryan Schiets is helping farmers dig for answers in their cornfields. Schiets, a crop adviser for The Andersons in northwest Ohio, says corn roots tell a valuable story that he and growers can quickly read and evaluate. With that information, they can then decide how to modify the grower’s management decisions to grow more profitable crops the next year.
“When you dig up those plants, the farmer really pays attention to what he sees; that’s much more effective than me just telling him what I’ve seen in his field,” Schiets says.
Bill Bauer, B&M Consulting, Coldwater, Mich., agrees. Bauer likes to have customers focus on what he calls the “money roots,” the three sets of crown roots that supply the bulk of nutrients and moisture to corn.
Limiting Factors. Corn roots should grow deep into the soil at a 35° to 40° angle, Bauer notes. If there’s no obstruction—compaction or a density layer—then corn roots grow vertically as long as they have access to water and oxygen. But if roots hit an obstruction, then they will turn and grow horizontally, or sideways. “When we’re turning a lot of roots, that puts limitations on the crop,” he says.
When roots turn and go sideways, the corn plant is unable to effectively absorb nutrients and moisture that might be deeper in the soil profile as summer progresses, Schiets adds. This results in less productive plants that are vulnerable to pests, disease and standability issues.
“Even this time of year, you can see if the corn crop has been affected by pests, like corn rootworm or cutworm, or if there was a planting depth issue or if there is a density layer the grower needs to address,” he notes.
Brad Beutke says there’s no sense in increasing nitrogen or pushing populations for higher yields when plants are faced with a density layer.
“In extremely wet or dry years, when a horizontal density layer has its greatest impact, we’ve seen 70- to 80-bu. differences in those fields compared to fields where the roots can grow down like they’re supposed to,” explains Beutke, a precision agriculture technology specialist for Crop-Tech Consulting Inc.
In Bauer’s experience, shallow density layers within the top 4" are more detrimental to yield than layers deeper in the soil profile. Use a tile probe to get an idea if a density layer or obstruction is present.
“Make a note of anything that stops your probe,” Bauer says. “It might be a density layer you hit.”
Harvest Priorities. Potential density layers are what Leon Knirk, who farms near Quincy, Mich., looks for as he evaluates corn crown roots late in the season. Hybrids affected by the density layers almost always have endured moisture and nutrient stress, and the stress results in premature stalk cannibalization.
“Those are the ones I’ll want to harvest first in the fall,” Knirk says. “If you don’t have any good nodes left, the stalk begins to get pithy and might increase stalk rot.”
Knirk checks representative plants of each hybrid and every field.
“The process takes a few minutes initially, but it gets easier and faster to do once you get over the mental aspect of cutting down your own corn,” Knirk says with a chuckle.
Crown-root checks can also help farmers adjust fall tillage practices to minimize density layer development, Beutke says.
“We need to think about what we’re doing in the fall before making our secondary tillage pass the following spring,” Beutke says. “Depending on what you see in the field, you might want the farmer to run an inline ripper or hybrid chisel to remove density layers. Leaving a level surface in the fall is more important as growers switch to vertical-type, secondary tillage tools.”
Schiets adds that by evaluating corn roots, he has helped growers modify some decisions and boost yields. He notes, “It doesn’t cost the grower a penny to evaluate his corn roots, but I’ve seen some make better decisions the following year that have improved yields up to 18 bu.—all because they did a root dig with me.”