Most years, you would be happy to kick a little mud off your boots in July. But when those boots are hip waders, the situation is serious. If you’re dealing with wet, saturated fields this summer, careful management can help those crops finish the season strong.
With abnormally heavy rains in many parts of the Corn Belt this late into the summer, your options become limited. The good news is that when fields flood at this point in the season, larger, more-established crops have a better chance at recovery. If you watch those flooded fields closely and give them a little TLC, you’ll improve their odds.
In corn, wet conditions — combined with warm summer soil temperatures — likely have contributed to nitrogen leaching. While there’s no tool or test to determine how much nitrogen has been lost, a worksheet from University of Minnesota Extension can help you estimate losses. Fields with early fall application of manure or nitrogen have the greatest potential for needing supplemental nitrogen. And there’s still time to make applications.
Studies show late-season nitrogen rescue applications pay off. Broadcast applications of urea or dribbling on 28 percent urea and ammonium nitrate (UAN) solution are effective strategies for providing corn with late-season nitrogen, University of Missouri research shows. Some leaf burn may occur with broadcast urea, but this translates into very little yield loss, if any.
Trials applying nitrogen as late as tasseling show effectiveness. Nitrogen uptake slows considerably after tasseling, as the plant shifts focus from soil nitrogen uptake through roots to translocation of stored nitrogen in vegetative parts into grain.
Flooded, saturated fields are perfect hosts for yield-limiting disease. As University of Wisconsin Extension research indicates, phytophthora poses the primary threat to soybeans. There’s also risk from pythium, rhizoctonia or fusarium. Different soybean varieties — depending on their genetic makeup — stand up better to disease.
In corn, certain diseases, such as common smut and crazy top, may become greater risks because of flooding, especially when flooding occurs before tasseling, University of Illinois Extension advises. A soilborne fungus causes each disease. Hybrid resistance to either of these two diseases is limited. Predicting damage is difficult until later in the growing season. Although these diseases can appear odd or unsightly, neither causes substantial yield loss.
Even when you monitor wet fields closely and work to help your crops fulfill their yield potential, agronomists advise that flooding and extended periods of saturated soils will take a toll on crop vigor. By taking immediate steps, you can help reduce losses. As this year’s floodwaters subside and fields begin to dry, watch for areas that remain wet. After harvest this fall, address drainage issues. Any improvements likely will pay off for years to come.