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Clarke McGrath, ISU: Corn Planting Depth?

Apr 16, 2014

By Clarke McGrath
ISU Extension


With the calendar edging close to mid-April, we are all anxious to start getting corn in the ground and I am getting calls on cold soils and planting depth. As fellow Crop Watch bloggers Jeff and Paul have shared, areas of our soil profile are still frozen, so the cold could be here a while. I have had a few asking about “can we plant a little closer to 1.5” or less to get this corn out of the ground faster since it may be cold?” In my very humble opinion, but based on years of digging up corn planted from 1-5” deep, targeting 1.5” is not my preference.

So how deep to plant?? Some agronomists say “2 to 3 inches”, and some say “1.5 to 2 inches”. Me, I say target 2”. So, as you get off the planter to check seed spacing and depth, take a good read on where it is at and make sure it is at least 1.75”, and remember that rain may (probably will) settle the soil around the seed zone and shallow up the planting a little — so plan your depth accordingly. This is especially relevant if you happen to run your trash whippers more aggressively. Disc openers tend to work better around the 2” target in my experience, too.

Target 2.5 if the soils get dry. Planting “too deep” (2.5-3”) isn’t typically nearly as problematic as too shallow, but I have seen some loss of stand, vigor and uneven emergence from 3” planted corn in cool, wet soils- occasionally. I see many more season long issues with shallow planted corn than deep planted corn, though.

Planting too shallow? Yea, big problems, such as rootless corn, sidewall compaction, poor root development, increased seed/root system mass in the herbicide zone, poor seed zone closing, the shallow seed zone can dry out, and no doubt I am forgetting some other maladies, but you see where I am going with this. Err on the side of “too deep” rather than too shallow.

Source : iowafarmertoday