Just as there's no one cause of compaction, there's not just one solution. "It takes a systems approach," says Ottosen, IA, farmer Dave Welter.
"The first thing you need to do is drain everything adequately. Then stay out of the fields when they're too wet to work," he says.
When Welter does work fields, he treads as lightly as possible. You won't find a tractor tire track in them. Welter pulls tillage tools with a Cat Challenger and does his row-crop work with a John Deere 8200T. "We deep rip cornstalks in the fall, field cultivate and plant in the spring," he says.
"You can see the effects of tire tracks well into the growing season," says Welter. "I'm getting compaction with tracks, too. It's just not as pronounced. I don't have hard data, but I'm confident that tracks pay for themselves. Under adverse conditions I expect I get at least a 5% benefit."
It's impossible to calculate yield losses to compaction accurately. There are far too many variables, according to Tom McGraw, Midwest Independent Soil Samplers, Buffalo Lake, MN.
"It's generally accepted that severe compaction can reduce yields by 20%," he says. "But the compaction that costs you 20% one year may only be 2-3% the next. It depends a whole lot on weather, soil texture, organic matter and conditions that limit the roots' ability to penetrate the soil."
Welter first tried a track tractor in 1990, when a wet spring left his 4WD tractors spinning and squirming across the field. "At that point I was mainly interested in the tracks for efficiency rather than for compaction control."
At harvest Welter uses the smaller track tractor and a grain cart with tracks to haul his crop to semis waiting at the field's edge.
Rather than putting tracks on his combine, Welter mounted 50"-wide logger tires on custom rims last fall. "I'm in the rollover program for combines, and it just isn't practical to change the tracks from one combine to another every year. I've got $13,000 in the tires, and tracks would have been roughly twice that much."
The extra-wide Firestone tires aren't without problems, though. Welter paid extra to get tires formed with steel cables for longer wear. But he's still concerned about stubble damage. And, he notes, "It would be a mess if one of them went flat out in the field."
Only time will tell if Welter's effort will pay. He farms with his son Jesse, who may be the real benefactor. "I'm 51 years old," says Welter. "I won't know all the benefits of farming this way until I retire."
At Humboldt, IA, Larry Lane already sees visible proof that minimizing trips and tire tracks is improving his soil.
"We've improved the soil texture. Water doesn't stand in wet spots anymore," he says. "We used to have some problems, even in tiled areas. So I know we're gaining some. And I don't see stripes in my fields anymore."
Lane minimizes trips across fields and consolidates the compaction he does create by staying in the same wheel tracks as he plants, sprays and rotary hoes.
"On bean ground going to corn, we float on herbicide, field cultivate, then plant. In cornfields going back to beans, we no-till."
Lane plants corn with a planter that he modified from a 16-row, 30" unit to a 20-row, 22" machine.
"I had been in 36" rows and needed to update," he reports. "I had read enough material on narrow rows that I decided to bypass 30". I really don't have any comparison for yield, but I get a quicker canopy for better weed control, and my row spacing is a lot more uniform."
The tracks that Lane leaves with the planter tractor are the same ones he follows with his rotary hoe and sprayer. "The planter is 36.5' wide, so I welded extensions on my rotary hoe to match that width and use a 73' boom on my sprayer."
Controlled traffic isn't a concern in soybeans for Lane. He no-tills beans with a 20' drill. "It's later in the season, the ground is drier and soybeans are just a lot tougher. Staying on one set of tracks is more important in corn."
Lane also tries to minimize the print that he leaves each time. "We don't run any ballast in the tires. We try and run as light as possible."
He decided to give controlled traffic patterns a chance after listening to Illinois crop consultant Kirk Wesley. In his presentation, Wesley illustrates that if you diagonally field cultivate once with a 30' tillage tool, plant with a 30'-wide planter and make one pass with a 45' sprayer, you've driven over 42% of your field and compacted, to some degree, that area. But if you made those same three trips with matched 60' equipment, you would only drive on 5% of your field. (Read more about Wesley's compaction management on his company's Web site: www.keyaginc.com.)
Even more critical is that you make those trips when potential for compaction is the greatest.
"Soils are most vulnerable in the spring when they've reached their water-holding capacity. Any time you're in the field before the seed is planted, it's risky. It's a small but very fragile window of time. Just driving a pickup across the field to deliver lunch can cost 3-5 bu/acre in the rows on each side of the track. Once the crop roots start to pull moisture out of the soil, it's much more stable," says Wesley.
"I think it's important to keep the air space in the soil," adds Lane. "It's like air shocks on a semi cab - when there's air in the soil it bounces back when you drive over it. When you squeeze that air out, it can't get back in."
Minimizing trips and tracks reduces costs and compaction, he says. "You save a lot of fuel by minimizing trips, and there's a lot of iron that you don't wear out."