The debate is age-old. Even when corn was checked and depth control far less precise, farmers had to decide what depth they wanted to try to place corn. Today, you can put it almost exactly where you want it with modern planters equipped with all the bells and whistles. But the debate is still ongoing – how deep should you plant it?
Two years of studies by Indiana Prairie Farmer and Purdue University, via Jeff Phillips, Tippecanoe County Extension educator, using grants from Precision Planting, showed that corn performed as well planted a full four inches deep as planted three inches, two inches or one inch deep.
In fact, in one year, the one-inch planting was 20 bushels behind the other plantings because germination was affected by rain events within the first week of planting. The corn never caught up in maturity or production potential all season long.
There is an important caveat, however, these tests were in warm soils in mid-May or later. The test was not done in cool soils.
Other company tests have seemed to agree that planting down to three inches is better than planting shallow. One theory is that if corn is planted two to three inches deep, the young roots will be positioned deeper in the soil. The depth of the root system and where it is anchored can become an issue later in the year if it turned dry.
Related: Farmers Need To Adjust Seed Depth
So what do you do if you are out in the field now and have to make this decision? One farmer who raised more than 300 bushels per acre last season in one field says he plants deeper than most of his neighbors. However, he's still not comfortable going more than about two and one-half inches deep for corn.
If there is a lesson to this story, it might be that erring on the deeper side rather than going shallow on corn seeding depth pays, whether the soil is cool or not. How you define deep vs. shallow is up to you.