If you've already planted corn, odds are you didn't plant it 4 inches deep. But if it's dry in your area, did you go deeper than 2 inches, often considered the standard for corn seeding depth? Or did you gamble for rain and go even shallower than 2 inches?
Precision Planting-sponsored studies in cooperation with Indiana Prairie Farmer and the Tippecanoe County Extension Service, with help from the crew at the Purdue University Throckmorton Research Center south of Lafayette, Ind., over the past two years said there was no significant difference in emergence or yield for corn planted 3 inches deep vs. 2 inches deep. That wasn't true of corn planted only one –inch deep, however. Two years ago the stand was significantly thinner and yields significantly lower for corn planted one -inch deep compared to corn planted at two, three and four- inch depths.
Still, farmers give me funny looks after reading about planting corn 4 inches deep. And perhaps they're right- if they planted their corn at that depth, maybe it would all rot. It hasn't in the plots so far, but the kicker is that we haven't been able to plant before mid-May, into cooler, more challenging soil conditions.
We hope to add to that part of the information base this year. A study is planned and hopefully corn will be planted soon, if it's not already, to determine what happens with such deep depths early in the season.
If modern hybrids really do have the ability to emerge from deeper depths even under cool conditions, then it would make one decision easier. If you were on the fence about how deep to plant, you could err on the side of going too deep rather than too shallow. The replicated data already says you can do that, and perhaps should do that, if planting in mid-May or later into decent soil conditions.
Fickle late spring and early summer weather patterns with thunderstorms and hot temperatures can play havoc with seed planted at shallow depths, which may or may not be in enough moisture to germinate without more moisture. That's what happened in our replicated study in 2010. Some seed planted an inch deep apparently sprouted, then couldn't keep going until rain came. The one-inch planting depth ran two lead stages and about 20 bushels of yield potential behind all other planting depths all season long in 2010. The difference wasn't pronounced last year.