April 19, 2013

With the later planting season this year, some producers may consider planting shallower to get the crop up quicker. Unfortunately, the corn roots may not develop properly when planting too shallow and the stands may not grow uniformly. To develop a good root system and more consistent stand, plant corn 2 to 3 inches.

Most corn planters are designed for at least a 2-inch planting depth. When running at least 2 inches deep the openers cut through the residue and soil better and form a better seed-vee.

When planting shallower than 2 inches, the angled closing wheels on many planters pack the soil below the seed and don't properly close the seed-vee. This problem is worse in wet conditions as the wet soils are easily compacted, reducing the penetration ability of the corn roots. When the soil dries, it shrinks some and, depending on the clay content, the seed-vee may open up, drying the soil around the seed even faster. If the seed-vee was smeared some at planting time, this smeared surface will bake hard, making root penetration even more difficult. Even if the corn was planted at least 2 inches deep, soil smearing and seed-vee opening may still be a problem if the corn was "mudded in." Waiting for proper soil conditions can help ensure your corn gets a steady start.

Also, when planting shallow, the seed zone is more likely to dry out. While the soil may have been fairly wet at planting, the top layer of soil dries fairly quickly. If there is an extended warm, dry period after planting, there may not be enough soil moisture in the seed zone to get all the seeds germinated uniformly. Some plants may get started early while other seeds are waiting for a rain for enough moisture to germinate. Worse yet are the seeds that germinate then die because they didn't have enough soil moisture to establish a plant. Planting deeper provides a more buffered soil moisture for a more uniform emergence and more moisture to get the plants established. The soil temperature is also more buffered, resulting in more uniform growth.

For more planting tips, check the 2013 CropWatch Archive for additional articles.

Paul Jasa
Extension Engineer