by Eric Nixon
With planting challenges still fresh in our minds from the 2019 planting season, understanding the importance of proper seed depth and spacing while planting in less than ideal soil conditions will benefit your corn crop with a great start this spring. A planting depth of 1.5 to 2 inches is optimal for nodal root development. It’s never recommended to plant shallower than 1.5 inches.
It’s easy to determine your planting depth after seedling emergence. The nodal root area (the crown or growing point) typically develops about 3/4 of an inch beneath the soil surface regardless of seed depth. To get your planting depth, measure the area between the seed and crown, then add 3/4 of an inch to determine the planting depth.
Corn that is planted too shallow lessens its ability to uptake necessary water and nutrients through the roots. Shallow-rooted corn is far less able to withstand periods of summer drought. It may also develop a condition called “rootless corn syndrome.” Plants with this condition may fall over due to lack of nodal development in dry soil.
To achieve the recommended planting depth, you’ll want to check for good seed-soil contact and strive for firm seedbeds that promote uniform emergence and stronger root systems. Slower planting speeds between four and five miles-per-hour will achieve more uniform planting depths.
Optimal spacing of corn plants is about reducing the number of misplaced and missing plants. Both outcomes will result in lower yield versus a uniform stand. Extra plants may increase yield slightly if the stand is below optimum. It’s recommended to make sure the target plant population is high enough to maximize profitability. Typical seed germination is about 95% therefore we recommend overplanting by at least five percent to reduce the effects of germination-induced skips.