
Kris Young (Sales Agronomist, Region 6 – Southern)
One year ago today, many growers were well into planting corn and I was planting plots already. Just yesterday, I had about ½ inch of snow with the biggest snowflakes I have ever seen. My kids were super excited watching the big, thick snowflakes floating down from the sky.
I know many growers in my area are getting impatient and feel like they are losing yield each day they are delayed to plant. They remember from last year that the earliest corn they planted yielded the most. Our calendar date tells us we are at the beginning of the planting corn season in the Eastern part of Kansas and Southern part of Missouri. However, our soil temperatures today are showing less than 50oF. When it comes to planting dates for corn, it is okay to be early but not okay to plant in less than ideal soil conditions. Remember the following key planting factors to reduce risk and maximize yield potential this season.
Soil Temperature – Above 50oF is the starting point for “ideal”. Seed planted into soils with a temperature below 50oF will absorb water and swell, but will not initiate root and shoot growth. This opens up opportunities for insects and diseases to attack seeds resulting in poor emergence. Corn typically requires from 100-120 GDD (growing degree days) to emerge. Under cooler soil conditions (50-55oF), emergence can easily take up to 3-4 weeks. As soil temperature approaches 70oF, emergence can be as little as 7 days.
Planting Depth – The recommended planting depth for corn is 2 inches. The absolute minimum depth should be 1.5 inches. This depth is important for establishing a healthy crown below the soil surface. The crown is where the growing point originates. Shallow planting depths can cause the crown to be closer to the soil surface if not right at the surface. High temperature and dry soils at the surface can restrict crown development and damage the growing point.
Seed Spacing – Equal spacing between the seeds in a row help the plants compete equally for water, sunlight and nutrients. For a planting population of 30,000 seeds per acre, the equal distance between seed is 7 inches. Any deviation over 1 inch (6 inch spacing rather than 7) can be a yield penalty as high as 2.5 bushel per acre.
Plant Emergence – Plants that do not emerge uniformly do not compete equally for water, sunlight and nutrients, similar to plants not spaced evenly. Based on research, there is a greater yield penalty for uneven emergence of plants versus the uneven spacing between plants. A consistent planting depth across the field into adequate moisture will greatly enhance uniform plant emergence. Make sure your planter is in good working order and don’t forget to set your planter at each field and when you change seed size.
Planting Dates – Planting date is important, especially field-by-field. Last year, we had a severe heat stress (110oF) period for about 3 days. The same hybrid planted 2 days apart under the same management conditions had different pollination outcomes. One pollinated well while the other was significantly less. Diversifying planting dates is important for managing risk against stressful environmental conditions occurring during critical reproductive stages (tasseling – blister). You can also manage this risk by planting multiple hybrids with different maturities.
The most important lesson I learned in 2012 was to be diversified. Timing is everything and is the difference between success and failure when growing corn in extreme drought and/or heat. We know we could experience the same type of heat and drought stress in 2013 as we did in 2012. The difference will be the “timing” of when this occurs. So be patient on when to start planting, be prepared with your planter, be diversified in your planting dates and hybrids and then go plant! Above all, be safe and optimistic each day.