What is in this article?:
- The average continuous corn yield penalty increases with more years of corn production, rising 268% from year 3 to year 7, according to Illinois research.
- “During a good year, there is very little continuous corn yield penalty,” says Joe Lauer, University of Wisconsin corn agronomist. “But in a bad year, the continuous corn yield penalty is especially bad.”
- In an intensively managed continuous corn system, removing half of corn stover boosted yields by 19 bushels per acre, compared to no stover removal, says University of Illinois soil scientist Laura Gentry, research leader. However, that wasn’t enough to recoup the continuous corn yield penalty, which ranged from 25 to 49 bushels per acre.
Residue prep is key
“Seedbed preparation is the most important thing for continuous corn,” Curtin says. They begin in the fall by sizing stover with a chopping corn head. After harvest, they deep-chisel plow to bury residue. That’s followed by one pass with a Case IH vertical-tillage tool to level and firm the seedbed. The next spring, they go over the field again with the vertical-tillage tool to incorporate herbicide and N. The Curtins also bale cornstalks from some fields.
In a corn-corn-soybean rotation, “farmers can get away with some types of reduced tillage, especially strip-tillage,” Gentry says. However, many continuous corn growers find they need full-width tillage after the second year to incorporate residue and speed decomposition, she says. That’s confirmed by University of Wisconsin research from 1983 to 2012, which concluded that conventional tillage boosted continuous corn yields 8-14% after the second year, compared to no tillage, Lauer says. “But it still does not overcome the continuous-corn yield penalty.”
Row cleaners on the planter are a key part of Keith Schrader’s residue-management system for continuous corn. Schrader, Nerstrand, Minn., has had very good results using floating row cleaners equipped with Precision Planting’s CleanSweep tool. Air cylinders mounted on the row cleaners let you adjust row cleaner down pressure, on-the-go, for changes in terrain or debris accumulation. “The main thing with corn-on-corn is to avoid seed contact with trash,” he says.