By Brian Hefty
About 10 years ago, we started planting more continuous corn on our farm in order to build our soil’s organic matter and capitalize on some good market prices. My dad was concerned about dry years because continuous corn needs more moisture than a corn/soybean or corn/soybean/wheat rotation. Other farmers cautioned me about planting continuous corn because, according to them, the yields aren’t as good as when crop rotation is used.
Like almost everything else on the farm, success can come IF continuous corn is well-managed. Look at many of the corn yield contest winners, including Herman Warsaw (the first farmer to raise 300 bushel corn in the U.S.) and Francis Childs (the first to 400 bushels per acre). These farmers ran continuous corn for many years and made it work great. After running about 20 percent of our acres in continuous corn for more than a decade, here are the five key points I would stress if you want to raise great corn-on-corn.
- Use more nitrogen and sulfur. Continuous corn means more carbon on and in your soil. A high carbon-to-nitrogen ratio means your nitrogen gets tied up. The same is true with a high carbon-to-sulfur ratio – your sulfur gets tied up. This will vary depending on your situation, but a minimum of 50 to 75 pounds of extra N and 10 to 15 pounds of extra S will probably be enough to overcome these problems.
- Use a chopping corn head. Whether you till, strip-till, or go no-till, having your residue chopped is probably a good thing. You will have fewer planting issues, warmer soil in the spring, and the residue will break down faster.
- Pick the right hybrids and/or use a fungicide. Goss’s Wilt and other diseases will be more common when you plant the same crop year after year. These disease issues will be even more likely to occur in reduced-till or no-till situations. As long as the diseases are fungal diseases, such as gray leaf spot, you can control them with a fungicide. If the diseases are bacterial, such as Goss’s Wilt, fungicides won’t work, so proper hybrid selection is crucial.
- Plan for problem insects, especially corn rootworms. In order to best control rootworms in the short-term and long-term, we suggest planting corn with two rootworm traits (SmartStax, for example), using a good rootworm insecticide at planting-time, and spraying for adult beetles around tasseling time.
- Do whatever it takes to avoid harvest loss. If you have corn that falls on the ground for one reason or another in the fall, that likely means volunteer corn will show up next year. How do you kill volunteer corn in a corn field? On our farm, we used to rotate Roundup and Liberty corn in our continuous corn fields so we could control the volunteers. Now that so few straight Liberty and straight Roundup hybrids are available, options are slim. If you have a lot of harvest loss, your best bet may be to rotate to a different crop for one year. Obviously, if you want to continue to plant nothing but corn, this is an issue.
In summary, despite last year’s drought, planting continuous corn is still a viable option on most farms. Just do your best to manage it well, following the steps I listed above.