Unless you use no-till or strip-till, tillage is the key to water movement. A variety of vertical-till harrows can be used to level fields after primary tillage, without putting in a dense horizontal layer.
How tillage can establish and maintain a vertical growing system that allows water to work its magic
Tillage helps manage old crop residue and creates a seedbed. We all know that. But did you know the primary purpose of tillage is to manage water?
For successful crop production, water must move up and down through the soil in a vertical format. If you fail to view tillage as a way to enhance water movement, your tillage tool can actually build a barrier to maximum yield. (If you no-till or strip-till, we’re talking about the tillage that occurs before transitioning from conventional tillage or to fix problems afterward.)
Water transports nutrients from the soil into the plant. It is the raw ingredient that makes photosynthesis possible. It constitutes 95% of each plant, and it literally gives plants the strength—called turgor pressure—to stand up. Water works its magic by moving upward from the soil through the plant, where most of it eventually transpires into the atmosphere, starting the entire cycle again.
Tillage is critical to the movement of water because water must be lifted upward through the soil to the plant roots. This lifting action occurs in two ways. One process is adhesion, in which water molecules hook to soil particles. The second is cohesion, which involves one water molecule hooking to another, moving water toward the surface in a wicklike action.
Ultimately, water leaves the field by evaporation from the soil and trans-piration from the plants. If the process hits a snag, water in the soil might be unavailable to plants.
The distance you can lift water varies with soil type. There are various management steps that you can incorporate to help keep water cycling. One of those steps is vertical tillage, which removes compacted layers and creates uniform soil density.
"If roots hit a man-made horizontal layer, they might not be able to penetrate it to reach water," explains Farm Journal Field Agronomist Ken Ferrie.
"In addition, the dense layer causes a barrier to water movement, weakening the adhesion and cohesion processes to the point that water can’t move up fast enough. Once the water near the surface separates from deeper water [creating two water fronts as opposed to one front], your corn plants might wilt, even though there is usable water below the roots."
Farmers understand the benefits of vertical tillage—a term you never heard until a few years ago. Industry has picked up on the concept too, as witnessed by the array of vertical tillage tools now on the market.
"But I see a lot of farmers making mistakes when transitioning from horizontal to vertical tillage," Ferrie says.
The vertical tillage system. "When a farmer tells me he’s switching to vertical tillage, I ask him about his entire tillage program," Ferrie says. "Too many tell me they simply switched to a vertical tillage harrow in the spring. They don’t understand that vertical tillage is a system, not a tool."
It might help to think of it this way: Your goal with vertical tillage is to set up a vertical growing system. That’s true whether you plan to continue doing vertical tillage every year or go all the way to no-till or strip-till.
Problems occur when farmers transition from horizontal to vertical tillage or when they mix and match components without understanding the vertical-tillage system.
"Disasters happen if growers simply switch from a soil finisher to a vertical-till harrow," Ferrie says. "First, you must do the primary tillage to remove old soil layers and set up the system."
Often, farmers don’t realize they still have water- and root-restricting layers beneath the soil surface since the emerging corn crop looks good from road, Ferrie adds. They never realize their crop ran out of water later in the season because roots grew sideways instead of downward and the upward movement of soil water was halted by a dense layer.
Various tools can be used to set up your vertical growing system, if you understand how to set and operate them to get the effect you want, Ferrie says. The only way to find out if you are setting the stage for vertical tillage, no-till or strip-till is to stop your tractor and dig behind your tillage tool.
"In vertical tillage, a spade is a must-have tool," Ferrie says. "If you have to search 30 minutes just to find your spade, you’re not ready to tackle vertical tillage."
To show the relationship between tillage and water, Ferrie devised a teaching tool for the 2011 Farm Journal Corn College. He ran three tillage tools, sometimes at different settings, followed by a vertical harrow to smooth the seedbed. He then dug soil pits to reveal the true condition of the seedbed.
Standard Coulter Chisel
In the first plot, Farm Journal Field Agronomist Ken Ferrie ran a traditional coulter chisel, just as it was set up by a farmer. The plot was based on a real situation in which a no-till farmer was forced to borrow a coulter chisel to incorporate limestone and level new tile lines.
"The coulter chisel’s points were worn, and some of them were bent back," Ferrie says. "Its ability to penetrate was not too good, but it turned the surface black. The farmer thought he was running the points 7" or 8" deep, but actually it was only 4". He was misled because he saw the soil he had thrown over untilled ground; the ridge of loose soil made him think he was running deeper than he really was."
Running shallower than expected can be even worse if there’s an old disk or cultivator layer under the soil surface, Ferrie points out. "The points won’t go through it; they will bounce off," he says.
The result was tilled valleys separated by undisturbed columns of soil. "It was a nasty environment for planting," Ferrie says. "After the surface ridges were brushed off with a vertical-till harrow, it didn’t look too bad. Beneath the surface, it was like a rumble strip on a highway.
"In this kind of situation, you will just feel a vibration in the tractor cab. But the planter units will bounce. The result of this ‘chatter’ will be misplaced seed. The sprayer operator will feel vibration, shaking and rattling."
And the corn plants? "Unless you get a saturating rain, plants over the valleys will grow faster and plants over the columns will grow slower," Ferrie says. "If it does rain, water will flow to the tilled valleys, and those plants will be waterlogged and yellow."
In this situation, a vertical-till harrow is not the answer. A soil finisher is a better choice.
"After chiseling with this tool, we ran a soil finisher," Ferrie says. "It sheared off the tops of the columns and leveled the surface. It left a dense horizontal layer, which will turn roots and give you trouble if you get too much rain or not enough. But it provided a seedbed you can plant into. The planter and sprayer will run smoothly, and you will get uniform emergence and stand.
"It’s not a good environment, but it’s better than a improperly run coulter chisel followed by a vertical-till harrow. I’ll take a perfect stand on top of a horizontal layer over a shoddy stand on top of vertical tillage."
If you find yourself in a similar situation, remove the horizontal layers—then you’ll be ready for vertical tillage.
Hybrid Coulter Chisel
In this plot, Ferrie ran a Great Plains Turbo-Chisel, on 15" spacing at two depths—5" to 6" and 8" to 10". In each case, he leveled the surface with a vertical harrow.
The Turbo-Chisel is in a class of machines Ferrie calls hybrid coulter chisels. "They are quite a bit more aggressive than a standard coulter chisel," Ferrie says. "Most of the newer tools are designed to level after they chisel. Leaving your primary tillage level is a key to vertical tillage—you want to be as level as possible behind your primary tillage tool. If you avoid having big peaks and valleys, you don’t have to move as much soil sideways to get the field leveled up."
Where he ran 5" to 6" deep, Ferrie found columns of soil that had not been tilled. "In your tractor and sprayer, you will feel the columns as you move over the ground," he says. "The columns will make your corn planter bounce out of the ground, so you will have deep- and shallow-planted corn," he says. "In this situation, you will be tempted to increase down pressure for better penetration of the columns. But if you do, you will plant too deep in the valleys or move too much soil."
If you have been doing this kind of primary tillage for years, you have probably leveled the surface with a soil finisher. "That fixed a lot of planting and growth problems," Ferrie says. "But if you use a vertical-till harrow following this type of primary tillage, the environment won’t be ready. You will have an uneven stand."
Where Ferrie ran the hybrid chisel deeper, he got uniform soil shattering across the width of the implement. "Now water can move upward through the soil profile," he says. "Buff the surface with your vertical-till harrow, and your planter will run smoothly."
The secret to using an in-line ripper, which is supposed to pick up the soil, drop it and leave the residue on top, is to run it at the proper depth.
In the Corn College plot, running the tool 11" deep created points that shattered the soil, but there was no lift between the points, resulting in columns and valleys. Leveling the surface with a vertical-till harrow helped, but serious planting issues were inevitable.
"In this situation, if you set enough down pressure to keep the openers in the ground on the columns, you will get sidewall smearing in the valleys," Ferrie explains. "Some plants will grow faster than others. Rainwater will flow into the valleys. The uneven growth will create issues with pollination and moisture levels at harvest."
You will feel the peaks and valleys in your tractor and sprayer. Because water percolates unevenly, during the winter you will have massive freezing and thawing where the point went through, but little in the soil columns.
Running the shanks 14" deep resulted in uniform shattering, with residue left on top to protect against erosion and evaporation. "Water can percolate down uniformly, so over winter you will get uniform freezing and thawing," Ferrie says. Leveling with a vertical-till harrow created a uniform seedbed.
Typically, half the width of your shank spacing is your targeted depth. "You do have to keep going down until the soil comes up evenly between the shanks and flows through the machine," Ferrie notes.
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- October 2011