As temperatures begin to warm and soils dry out, many planters will soon be in the field planting field corn around the state. As we look toward the 10-day forcast low temperatures remain the 30’s through the weekend of March 20th and chances of rain increase. A few things to remember as we proceed with planting include making sure planters are set correctly for corn. Seed meters working appropriately are important for corn ensuring that corn seed is singulated and planting population is accurate. In recent years, several researchers have been evaluating planting depth settings across the planter, and results have found that not all planters are placing seed at uniform depths from row to row even though the T-handle is in the same position, just something to be mindful of. Again, yield response to uniform emergence has been documented in corn so uniform seed depth and uniform emergence is important.
As soils remain cool, soil temperature should be evaluated prior to planting. Clemson’s recommendation is to plant corn when soil temperature reaches a minimum of 50 degrees F at a 4-inch depth OR 55 degrees F at the 2-inch depth. Furthermore, when we plant, we want warm temperatures (>50+ degrees) in the days following planting to ensure we can generate enough heat units to get the seed to germinate and emerge quick and uniform.
If corn is planted, and soil temperatures get cold enough (< 50 degrees to freezing), several things can occur. Uneven emergence, growth, and development across the stand, issues with mesocotyl growth and reduced vigor can be noticed, leafing out underground, and severe cases can cause seed and seedling death.
Corn germinates in a two-step process where first, corn seed absorbs approximately 30% of its own weight in water and second, the growth of the radical and coleoptile occur. The second step is dependent on soil temperature and if soil temperatures are below 50 degrees F, then initiation and growth of the radical and coleoptile will not occur or will be very slow.
With slow growing conditions, seed will likely be exposed to insect and disease pressure for greater lengths of time, which could lead to further issues with emergence or seedling vigor. Planting into cold moist soils can also shock the seed when water is absorbed causing seed death and result in variable stands or total replants.
