Proper Corn Planting Depth Critical to Successful Season

Proper Corn Planting Depth Critical to Successful Season

April 2, 2010

With these nice spring days, you may be eager to start planting, even in wet soils where planting may be difficult. Remember that many agronomic problems that occur later in the season start with how things were done at planting, particularly the planting depth you use. Problems can include:e proper depth.

  • restricted root development due to compaction
  • rootless corn syndrome
  • lodging
  • lack of surface soil moisture
  • variable emergence
  • potential damage from pre-plant or pre-emergence herbicides
  • potential fertilizer injury

Proper planting depth is essential for ensuring good nodal and brace root development. During the rush of getting the corn in the ground, especially under wet conditions, the planter is often raised up. Raising the planter can cause problems, though. Often variable emergence is observed. Also, as the seedlings grow, their roots may not become as established as they would if the seed were planted deeper. On windy days in May and June you’ll see the effects of rootless corn syndrome when seedlings flop around, braced only by the main radical root. This causes a great deal of plant stress with plants often becoming dislodged or dying due to a lack of root structure and moisture stress. This ultimately reduces plant population and subsequent yield.

Our May winds can quickly dry out the surface soil, resulting in a lack of soil moisture at the surface where seedling roots are found. Shallow rooting depths also can increase the probability of damage from pre-plant and pre-emergence herbicides. Damage from fertilizer also increases with shallow planting, particularly when fertilizing within that planting row.

It’s important to remember that many closing wheels are designed for a 2-inch seeding depth. Planting shallower than this results in the seed being in loose soil that will dry out more quickly and provide for less seed-to-soil contact.

Improper seeding depth also can contribute to agronomic problems later in the year such as increased stalk lodging due to inadequate brace root development. Brace roots on shallow planted corn often appear stubby and stunted and can be confused with symptoms caused by herbicide or nematode injury.

Research conducted by universities and the ag industry show that planting at a 2-inch depth compared to a 1-inch depth provides more uniform plant populations and better yields, thus our recommendation is to plant corn at least 2 inches deep. Many producers aim for a 1.5-inch planting depth; however, hitting old root stumps and not enough down pressure when cutting through residue can quickly raise that planting depth closer to the surface.

This season the Greater Quad County On-farm Research producers will compare 2- and 3-inch planting depths, particularly in no-till planting conditions.  (For information about on-farm, producer-driven research activities, visit the CropWatch Farm Research page.)

Jennifer Rees
Extension Educator in Clay County

Robert Klein
Extension Western Nebraska Crops Specialist