You’re getting ready to plant corn, and soils are drying out. If you plant 2 inches deep, some seeds might wind up in dry dirt. Do you drop the depth to 3 inches? Do you leave it at 2 and hope it rains? Or do you wait until it rains to plant?
It’s a question almost as old as the chicken-and-egg dilemma. It came up during sessions at the Precision Planting farm near Pontiac, Ill., last summer. Starting with the last question first, most agronomists shy away from waiting. Tons of data say over time, earlier planting pays. The recent trend documented by ag climatologists is that when it rains in May today, it often rains in buckets, not sprinkles, delaying your return to the field.
Jason Webster, who manages the farm and seminars for Precision Planting, points to data collected through company trials that indicates 2 inches may be the ideal planting depth for corn for top yields. However, there’s also clear evidence that depths of 2.5 to 3 inches produce better yields than planting at less than 2 inches deep. Err on the side of going deeper rather than shallower, Webster says.
Part of the dilemma is that knowing how much moisture is in the furrow at a certain depth is a judgment call. Now there is seed firmer technology that can provide better information for such decision-making.
“SmartFirmers report several things directly to the Precision Planting 20/20 display screen in the cab,” Webster says. “One thing they report is soil moisture content.”
For example, if moisture content is at 30% or higher at your desired planting depth, you know you have a decent chance of obtaining a uniform stand. If moisture is only 10%, it may be time to make a change.
Inconsistency across the field is another factor that complicates the decision. There may be sufficient moisture in one soil type within a single pass, but it may be drier than you’d like at your preferred planting depth in another soil type, Webster says. The SmartFirmer technology allows you to confirm exactly how much moisture content is varying. It gives you solid information for making decisions, he says.
Someday it may be possible to change seeding depth on the go. That would certainly come in handy in fields with different soil types. While that technology isn’t available now, don’t rule it out for the future, Webster says.
In the meantime, technology can at least give you accurate data. One decision some farmers are pondering this year is how many SmartFirmer sensors to add to the planter. Some have just four on a 24-row planter due to cost, while others have installed more to give more readings. Soil variability in your area may help determine how many you should invest in for your planter.