Think no-till or continuous corn systems through—or yields can crash
There were wide swings in corn yields last fall. Farm Journal Field Agronomist Ken Ferrie saw 90-bu. to 120-bu.-per-acre continuous-corn yields, just down the road from fields yielding 200-bu. and 240-bu. He suspects farmers made big changes to their crop practices without thinking the system through. The systems approach is something he teaches at Farm Journal Corn College.
"The biggest yield crashes I see usually involve a transition from one production system to another," Ferrie says.
Examples include switching from a corn-soybean rotation to continuous corn or from horizontal tillage (disk, moldboard plow or field cultivator) to vertical tillage (or, as Ferrie says, "farming in a vertical format").
Farming vertically is more than just tillage, Ferrie says: It’s a system designed to keep water and nutrients moving up and down, as needed, through the profile.
Failure often results from not removing dense soil layers before transitioning into no-till or strip-till.
"If you have a sudden change in soil density under the surface, preventing water from percolating down, and residue on top, preventing it from evaporating, you may have to wait for the field to dry out for planting," Ferrie says.
He recommends spending up to three years to prepare soil for no-till planting. The first step is to remove dense layers with vertical tillage tools, such as in-line rippers. "Forget the myth that freezing and thawing will take out a sudden density change. It can’t remove a layer from a soil finisher or moldboard plow," Ferrie says.
Shallow sudden density changes are one reason why farmers who are successful with conventional horizontal tillage, run into problems with no-till.
The way to identify dense layers is to dig in your field and examine soil structure and root growth. "If you are already no-tilling and experiencing problems, you may have to get out of no-till for a while and do some vertical tillage," Ferrie says. "Once you have removed dense layers, and improved drainage if necessary, no-till can be very successful."
Some farmers slip up by not understanding that vertical tillage may require two steps: breaking up dense layers in the fall, with vertical primary tillage, and then leveling the field in the spring—without putting in another layer. That requires a vertical-till harrow in the spring, rather than a field cultivator or soil finisher. "The last pass before converting to no-till must be vertical," Ferrie says.
Transitioning to vertical tillage may be a two-step process. The first step may require deep tillage in the fall to remove dense layers.
The second step is leveling with a vertical-till harrow in the spring. Using horizontal tillage in the spring puts in a new dense layer.
Nutrient preparation. Removing dense layers allows you to work through other aspects of your new system, so problems don’t emerge later. If you plan to no-till or strip-till (as opposed to using vertical tillage tools every year), you must balance pH and fertility in the soil profile. Acidity or low fertility levels lower in the soil profile may not hurt yields when there is adequate moisture and normal temperatures. "But if surface temperatures get too hot and the roots in the top 3" die, the plant will be forced to feed deeper," Ferrie says.
"If soil pH is low, incorporate lime through the top 6" of the profile," he says. "Trying to correct acidity in the top 6" of soil with surface applications could take 12 years, because lime moves down only 1⁄2" per year.
"After you correct the pH in the profile, you can lime from the top. I know no-till growers who have maintained pH that way for 25 years. But if you start out with an acid soil profile, lime applied on the surface can’t move down fast enough to correct it," Ferrie adds.
Follow the same procedure with phosphorus (P) and potassium (K), incorporating it into the top 6". After you move into your no-till or strip-till system, you can feed from the surface.
"Where no-till growers have removed sudden density changes and built up subsurface fertility during the transition period, their P and K levels at the 3" to 6" depth have remained the same for 20 years," Ferrie says.
Stratification. "After you begin no-tilling, you will get some stratification at the surface, but that usually is not a bad thing," Ferrie adds. "Stratification is really a form of banding—it can be beneficial if you are fighting K availability problems."
Failing to understand that a new system requires equipment and management changes has left more than one farmer disappointed at harvest.
Plan what kind of planter attachments you will need. "In a high-clay soil, that will be something that will do tillage ahead of the double-disk openers," Ferrie says. "This could be a wavy coulter, a row cleaner or a combination of both. They do a little tillage, so the disk opener on your planter won’t create sidewall compaction. You also need a row cleaner to sweep away residue.
"On very sandy soil, if your goal is to leave residue on the surface to conserve moisture and prevent erosion, use a sharp coulter, bubble or slightly fluted, without a row cleaner. You want to place seed beneath the residue, without hairpinning residue in the furrow."
You may need to change attachments from field to field. "Coulters are only for no-till," Ferrie says. "If you have fields in horizontal tillage—or if you are moving from no-till to a vertical-tillage program to correct problems—a coulter will work against you. In tilled soil, the coulter has no cutting platform, so it will push residue into the seed furrow."
Before you abandon horizontal tillage, plan a herbicide program to control winter annual and perennial weeds. "A carpet of weeds in a wet spring prevents soil from drying," Ferrie says. "And it can be almost impossible to plant into."