No-tilling in heavy residue
Paul Jasa just can't get enough corn residue. The University of Nebraska engineer and longtime (over 30 years) no-till advocate views the increase in residue from higher populations, corn-on-corn, and Bt varieties' resistance to breakdown as blessings. “I can show you a picture where I planted soybeans into 220-bushel corn residue,” Jasa points out. “The soybeans are coming up, and there's no residue left. It's gone. We are looking for ways to get more residue out in fields because the corn residue breaks down too fast.”
That is why researchers like Jasa and Richard Wolkowski, University of Wisconsin engineer, advise against flail or rotary chopping corn residue in the fall. “Stalks deteriorate more rapidly left standing in the field,” Wolkowski says. “Plus, chopping can leave a mat of residue that may keep a no-till surface wetter and colder in the spring, whereas unchopped residue remains upright, allowing for better air circulation and drying.”
Wolkowski and a University of Wisconsin research team have conducted field studies comparing no-till to chisel fields in continuous corn. That research found, for example, that chopping stalks followed by chisel-plowing did reduce surface residues from 61% down to 42%, on average. But that treatment did not affect the early-season soil temperature, emergence rate, final stand, early-season plant height, or corn grain yield.
“We compared this to no-tilling in which we used finger coulters to remove residue ahead of the double-disc openers,” Wolkowski says. “What we have seen so far is that no-till performs very well (without an additional treatment such as chopping). If it's done properly and if other things (such as fertility, weed, pest, and traffic management) are taken care of appropriately, I think a no-till system performs very well in heavy residue in corn-on-corn.”
Residue manager selection
When it comes to residue managers on planters, Phil Needham of Needham Ag Technologies prefers floating row cleaners. “Years ago, fixed row cleaners rigidly mounted to the planter unit were the thing to use. Most farmers now buy a floating row cleaner, which has a pivot point on it that allows it to float up and down with the contours of the ground and remove residue consistently,” Needham says. “Some say that's a kind of strip-till. I don't think it is because there's no prior tillage.”
The bottom line is residue managers allow you to part the residue and plant at a consistent depth, Needham says.
Nebraska's Jasa says residue management in no-till begins at harvest. “In the early days of zero tillage, I liked to run the corn head about 6 to 8 inches off the ground so I'd get all the residue processed through the snapping roll,” Jasa recalls. “Now, I run the corn head 18 to 24 inches high. That way, more corn is standing up and not touching soil microbes. Corn hangs around longer for me in the spring. The standing residue catches snow rather than letting it blow away. It also keeps the sun and wind off the soil surface to conserve soil moisture.”