An enthusiastic group of nearly 75 farmers gathered in Atlanta this week for the inaugural Farm Journal Corn College South event, held in conjunction with the 2011 Ag Connect Expo.
During the two-day event, Farm Journal Field Agronomists Ken Ferrie and Missy Bauer fielded a variety of agronomic questions about raising corn in the South. Here are a few of the questions growers asked, as well as summaries of answers Ferrie and Bauer provided.
What causes short corn ears?
A variety of stresses can contribute to this problem, depending on the year. Insufficient nutrients and/or excessive heat are common causes. Insects, disease and drought can also contribute to the problem.
How can I use nitrogen effectively in corn?
Knowing how a corn hybrid responds to nitrogen can help you determine where to place that particular hybrid in your fields and how to manage the nitrogen that it needs. Part of that process includes knowing that the amount of carbon present in a field impacts nitrogen availability. We call this the carbon penalty, and it’s good that growers know that large volumes of crop residue will lead to the immobilization of nitrogen in their fields. In corn-on-corn or fields with a high carbon penalty, plan on using extra caution in managing nitrogen with those hybrids that prefer it early. If you plant hybrids that like nitrogen late and on soils with high susceptibility to leaching and denitrification, a late-season nitrogen application may be beneficial.
How do I know whether I’m achieving adequate down pressure when I plant?
- Use these guidelines to manually check down pressure:
- Stop your planter in the toughest part of the field and leave it in the ground.
- Grab the depth wheels and see if you can spin them.
- One wheel should be making contact with the ground to the point where you can slip it, but it is difficult to do so.
- If both spin free, there is not enough down pressure.
- If you can’t slip the wheel, then there is too much down pressure.
- You want good solid contact, but you also want to be able to slip the wheel.
- You can also observe the effects of down pressure above ground. Walk behind your planter pass to look at the planter footprint--the depressions and imprints left by the depth wheels. The footprint of the planter can tell you what kind of down pressure is needed. If the footprint isn’t consistent, there is not enough down pressure. A very pronounced footprint means that a lot of soil was moved around by the planter and there is too much down pressure.
What causes uneven spacings in corn?
After corn emerges, there are simple ways to determine the causes of problematic plant spacings. For instance, a double occurs when the planter meter picks up two seeds and drops two at the same time. In the field, you can tell whether this is what occurred when it looks like you have good uniform spacing on either side of the two plants that are too close together. However, a misplaced seed looks different from a double. With a misplaced seed, while the spacing is still real close together, you will see a gap from where the seed should have been on one side of the grouping. In this case the meter functioned properly in releasing one seed at a time, but there was ricochet in the seed tube, which caused the seed to bounce and the timing to be off.
Is manure a good source of nitrogen for corn?
The nitrogen in your manure is as good as any other source of nitrogen you can buy.
Neither manure nor banded nitrogen do a good job of paying the carbon penalty in the spring, however, because the manure has to decompose to become available to the corn. You’re applying the nitrogen in a concentrated form, which doesn’t help the breakdown of residue on the surface, and it’s too far away from the small plants.
Once your corn plant gets enough depth of root, it should reach the nitrogen and pick up its color to turn green. But corn can go through a tough period before its roots reach the source of nitrogen. Think about backing up your manure rate. And save some of your nitrogen to apply in a spring surface application, or put some of the nitrogen allotment on with your corn planter. Applying nitrogen with the planter will help the corn early on until it can grow to reach the banded manure.