By Dick Hagen
The Land Staff Writer
— Maybe we need to think more positively about trash. We’re talking trash as residue left on fields after harvest, or any time as a matter of fact. Does it have value?
“Trash is worth a whole lot,” said Mike Petersen, a precision tillage agronomist with Orthman Manufacturing, Lexington, Neb.
Speaking at the recent Conservation Tillage Conference at Jackpot Junction, he said, “if you take five tons of residue remaining on the soil surface we know we have 150 pounds of potassium, approximately 40 pounds of nitrogen, 17 to 20 pounds of phosphorous, 15 pounds of sulfur and a bit of zinc.”
About 5 tons of residue is what a 200-bushel corn crop is producing these days. That residue also provides a soil blanket guarding against erosion. “But you still have to deal with it to make ready your seedbed, and strip till is one way to make it happen,” Petersen said.
He questions the need to chop corn stalks, even in a continuous corn program, if you have the right tools — planting equipment with trash whippers and special coulters for precise fertilizer placement.
“Corn stalks don’t need to be sized. There’s good equipment out there now for working through residue. But a good tool is a $3 to $5 soil thermometer. Test that soil temp in several locations, depending upon your landscape. When your soil reaches 52 degrees at 1 inch, then get planting,” he said.
If nitrogen didn’t get applied last fall, what’s the best route this spring? Petersen said side-dressing, or possibly even top dressing and foliar work later in the growing season. “It generally pays to spread out your N application because the crop can’t use it all at once.”
University of Minnesota soils specialist Dan Kaiser said there is no field research suggesting applying nitrogen helps to break down corn residue. But if bedding is needed, baling residue certainly alleviates the problem if you don’t have equipment for planting in residue.
“Regardless,” Kaiser said, “make sure your planter is equipped with row cleaners in good working order. You’ll want clear rows for stand establishment, especially in continuous corn.”
Petersen claims inversion tillage (V ripper, chisel plow, moldboard plow) has boxed growers in to keep tilling to break apart the “solidifying state” of the soil. He also blames inversion tillage for mauled and diminished worm populations and other soil invertebrates.
According to Petersen, too much inversion tillage has:
“We believe vertical tillage and fertility placement needs to be precise with the seed. Since the first commercial draft plow was used in 1847, soil structure, organic matter, soil porosity and microbial populations have been detrimentally affected to the point of soil being mush.”
Should you be more particular about your hybrid choices in reduced tillage, especially in a continuous corn program?
Jim Christenson, a crop technician with Gold Country Seed, definitely likes to explore hybrid options with his customers.
“If residue is becoming a challenge, I suggest they look at shorter hybrids, plus hybrids with strong emergence because typically you’re planting in colder soils,” he said. “And I also look at root structure. You want a hybrid with robust roots.”
He cautions against switching to earlier hybrids in reduced tillage, unless corn planting gets delayed beyond May 25. But in a no-till or strip-till environment, he suggests GCS 95-11 (95-day) because of its broad disease package supporting plant health from early root development to late-season. A new hybrid, 94-29, is another choice because of its shorter plant height and durability, even in more difficult seedbed conditions.
To achieve desired harvest stands in reduced tillage he suggests 34,000 plants per acre as a starting point. Christenson also advises seed treatment such as Acceleron (combo product with two fungicides, one insecticide) for soil problems such as pythium, rhizoctonia and fusarium. “The Acceleron seed treatment includes a plant health protein that increases the plant’s defense mechanism.”
Because growers are planting earlier, U of M plant pathologist Dean Malvick suggests seed treatments need to be considered. Dave Schwartz of Gold Country Seed added, “Since we started treating with Poncho 250, we just don’t get calls anymore from customers complaining about their corn stands because of wire worm or white grub damage. On soybeans, as seed costs increase, I think seed treatment is basically just good insurance.”
Summing up
Trash has value but it needs special attention. Strip till appears to be a winning choice for more farmers, especially in continuous-corn programs. Tillage reduces organic content of your soils and, over time, reduces soil carbon content. Anything you can do to build soil carbon is good, so reduced tillage needs to be a consideration.
Petersen said farmers are dealing with considerable hype about crop traits, genetic development, yield potential and many other “above-ground” aspects of modern corn production.
“But what a grower really wants is perfect seedbed, best possible root system development, proper/precise placement of nutrition for the plant, and the fewest passes across that field before planting to give that high-powered hybrid a shot,” Petersen said. “Strip till can deliver, and with less fuel, little or no erosion, even better nitrogen utilization. So don’t fight your residue challenges; learn how to work with it and rebuild your soils in the process.”
Recognizing the probability of some serious trash issues this spring, the question was asked, “if all else fails, how about just raking the field and torching the trash?”
As expected, sudden quiet.
But George Rehm volunteered, “if burning is the last solution, so be it. You’re losing that nitrogen, and some carbon. But the P, K, S and Zn would still be in the ash residue. You gotta do what you gotta do, it’s that simple.”
For more information from Mike Petersen, precision tillage agronomist at Orthman Manufacturing, e-mail mpetersen@orthman.com.
