As harvest wraps up around the country, Ken Ferrie says he is fielding a lot of farmer calls about 2019 cropping decisions. Some growers, in anticipation the tariffs with China will be resolved, are contemplating going with beans-on-beans. Still, other farmers have the opposite mindset and are considering planting corn-on-corn.
Based on test plot results, he says to anticipate taking a 5-bu. to 6-bu. per acre yield hit with beans-on-beans versus yield results in a bean-after-corn rotation.
“That was the case in our beans-on-beans plot this year. Our early April planted beans-on-beans yielded 80 bu. on average compared with 86-bu. [in the rotated plot],” explains Ferrie, Farm Journal Field Agronomist.
Ferrie isn’t 100% sure why the yield lag exists but expects it is due to disease or insect pressure, or some combination of the two. He adds the 2018 season was a good year for fungicide-insecticide use.
“We saw a zero to 8-bu. response range to applications in soybeans with a lot in the 3-bu. to 5-bu. range,” he notes. “Early planted April soybeans had a stronger response to the applications than later-planted beans.” He adds tillage practices made little to no difference in response.
Farmers who grew beans-on-beans this year and are going to corn in those same fields in 2019 are likely to see less disease. “That should help lower corn nematode populations but it might not help with first-year corn rootworm issues,” he notes.
Ferrie says if farmers documented a lot of rootworm beetle in their bean fields this year or on their combine at harvest, they’ll need to protect their 2019 corn crop from rootworm. “Eliminating a fungicide from your program next year might not be feasible then,” he says.
Farmers who rotate bean-on-bean fields back to corn often ask Ferrie if they will get a double-nitrogen credit and be able to reduce their nitrogen use. He says the short answer is no.
“Set your nitrogen rate for first-year corn, and then back it up with in-season nitrate testing at sidedressing time,” Ferrie says. “If the testing says you can pull back on your nitrogen at that point, then do it, but don’t budget to do that.”
If you go with a second corn crop on the same fields next year, Ferrie says to anticipate a 10% to 15% yield reduction. “Make sure you account for the carbon penalty, diseases and insects, and that might minimize the hit you take,” he says. “But if Mother Nature turns things dry long enough in the season, corn-on-corn will suffer, and there’s not much you can do about it.”
Hybrid selection is crucial for good corn-on-corn results. Top-yielding hybrids in a corn-soybean rotation might not be your highest-yielding hybrids in corn-on-corn ground because they might not be able to handle the stress that commonly accompanies a lack of rotation. Ferrie says to consult your seed rep for corn-on-corn recommendations.
Each week, Farm Journal Field Agronomist Ken Ferrie shares practical agronomic insights based on his field research and observations. To listen to the latest episode, look for the “Podcasts” section on AgWeb.com