Getting corn off to the right start begins the instant the seeds hit soil. Be sure to keep a close eye on soil temperature and planting depth to kick your season off right.
Cool soil can prevent good stand establishment. According Iowa State University, corn should generally be planted when soils are near 50°, with temperatures on the rise. Seed absorbs 30% of its weight in water, regardless of soil temperature. You’ll start to see poor emergence in cool soils because seeds will absorb water, but they won’t begin root or shoot growth. If cool conditions continue, the seeds can rot which could mean you need to replant.
You’ll see greater yield reduction from planting too late rather than too early though, according to Iowa State research. Reduced growing degree days (GDD) are to blame; corn needs a certain number of GDDs (dependent on corn’s maturity) to effectively reach tasseling and will also need time for grain fill and dry down.
Carefully weigh soil temperature limitations with GDDs to optimize your planting date.
Ag Weather Maps
- Precipitation Maps -- From average rainfall to long-term outlooks, these maps give you an idea on what you can expect.
- Soil Maps -- Soil temperature, water needs, crop moisture and more. Stay on top of your field's needs this growing season.
- Temperature Maps -- Too hot, too cold or just right? These maps tell the future and keep you one step ahead of Mother Nature.
- Growing Conditions Maps -- Should you expect frost soon? Are heavy winds headed your way? These ag weather maps will help you plan your day, and identify risks to your crop.
When you get to planting, make sure the seed is deep enough to establish strong roots and stand up in the wind. Most university Extension publications across the Midwest recommend planting corn 1.5” to 2.5”.
However, Greg Luce, adjunct instructor in the division of plant sciences at the University of Missouri, recommends planting more toward the deeper end.
“I recommend targeting 2” as an excellent depth for corn planting,” says Luce in a recent university publication. Good seed-to-soil contact is essential for plant growth, and he says planting at 2” provides consistent moisture levels and can assist with more uniform stands. In addition, a 2” planting depth can help corn establish a strong nodal root system to support plant structure, nutrient uptake, reduce early season lodging and help the plant endure drought stress better.
Planting at 1.5” or less could leave your corn susceptible to lodging or corn injury from pre-emergent herbicides. Luce says some circumstances, like dry soil conditions, might even indicate planting deeper than 2.5".
Talk to your local agronomist to see what he or she recommends for planting timing and depth based on conditions in your area.
Do you anticipate waiting longer to plant this season based on soil temperatures? How does moisture level affect seed depth on your farm? Tell us how your planting season is going by sending your photos and notes to AgWeb's Crop Comments section.