The planter monitor in your tractor cab insists the seed corn is tucked away at a 2.5-inch planting depth, but Randy Dowdy says to question that placement. The high-yield row-crop grower explains there is often a difference between what the planter monitor says and what the soil shows — and the gap between the two can rob farmers of yield potential before the crop ever breaks the soil surface.
“You have to distinguish between the planting depth and what we call the germination depth. It’s a potential problem we talk about all the time with our farmers in Total Acre,” says Dowdy of his agronomic business he co-owns with David Hula, world champion corn grower.
Iowa State Extension defines planting depth as the placement of the seed corn in the soil, while germination depth (emergence) is where the corn nodal roots will form, regardless of the planting depth.
The discrepancy that can occur between the planting depth and germination depth often happens at the moment the seed trench is closed or shortly thereafter. The planter might place the seed at 2.5 inches, but the closing system can shift seed upward — especially in dry, loose soils. As the dirt settles the seed can end up germinating at a significantly shallower depth than the grower intended.
“When we check seed placement in an open furrow, there’s no doubt about it, we were planting at 2.5 inches,” Dowdy notes in a recent video. But as he moves behind the machine to inspect the closed row, the reality changes. In Dowdy’s field demonstration, the shift is dramatic, showing the seed is now sitting much closer to the soil surface.
“When we dig into that closed trench, we find that the seed is now sitting in the ground at about 1.5 inches to 1.75 inches, and that’s not what you want,” Dowdy says. Watch the video on Farm Journal TV.
The result of that shallow germination depth is a fundamental threat to corn, Iowa State Extension reports. Shallow germination can impact early root development and contribute to rootless corn syndrome, susceptibility to herbicide injury, poor drought tolerance and other issues that can impact growth and development throughout the season and, ultimately, reduce yield.
To combat this, Dowdy’s philosophy is simple: trust what you learn using a shovel to dig behind the planter to locate the seed; don’t depend only on what the planter monitor in the tractor cab shows.
Dowdy and Hula advocate for establishing a consistent germination depth for seed corn across the field, ensuring that plants have the strong foundation they need to thrive.
“For proper root development, we like to maintain a consistent two-inch germination depth,” advises Dowdy, who’s based near Valdosta, Ga.
Dan Quinn, Purdue University Extension corn specialist, says the “most common seeding depths recommended for corn range between 1.5 and 2 inches deep, and these planting depths can work very well within most conditions, however, certain soil moisture conditions at planting may warrant further examination/change in seeding depth.”
This year, with dry soil conditions in the Southeast, farmers have had difficulty achieving a 2-inch planting depth consistently for good emergence. Dowdy’s directive to growers in dry ground is to account for the “settle” in soils at planting by adjusting planter settings to go a bit deeper with planting.
Iowa State Extension agrees, noting that a 3-inch depth is usually OK in drier soils. While deeper planting can take slightly longer to emerge, it can lead to more uniform stands compared to shallow planting.
“My advice in these (dry) conditions is to plant a bit deeper, knowing the ground will settle, and you’ll get better root development,” Dowdy says.
By prioritizing the physical reality of the seedbed over the digital feedback in the cab, Dowdy believes farmers can unlock better performance without any additional overhead. By doing so, growers “will do a better job, and you’ll have proper root development and help you on your yields for free,” he says.
You can hear more about how this season is shaping up for Dowdy and Hula on their latest edition of Breaking Barriers With R&D podcast with Chip Flory on AgriTalk. Listen at the link below:
