Cut Compaction, Boost Yields

While there's no avoiding running heavy equipment through fields, there are ways to minimize the soil compaction that results. The stakes are high: soil compaction from heavy equipment can lower corn yields by 20%, erasing your profits. Vertical tillage eases the problem.

By Rhonda Brooks, Farm Journal Seeds & Production Editor

Six-foot-tall corn with stunted ears was a common sight in Luke Huysman’s fields during 2012 due to extreme drought conditions. In the years prior, Huysman saw the same short corn but for a different reason. The contributing problem then was compaction. Plaguing 600 to 700 corn acres, compaction was evident wherever trucks, heavily laden with manure, had traveled over the gently rolling fields.

Today, the problem is basically nonexistent on his Fabius, N.Y., farm, which includes 4,400 acres of corn and alfalfa-grass hay and a 1,400-head dairy cow operation. Huysman owns the farm with two partners.

The solution to Huysman’s compaction issues was vertical tillage. The practice involves tillage  that’s deep enough to break up hardpans and horizontal layers.

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Complete, full-bore shatter between the tillage tool shanks and also between passes is needed to make vertical tillage effective.

"The ground upheaval resets the soil profile," explains Frank Mutz, Empire Tractor territory manager based in Cazenovia, N.Y.

Farm Journal Field Agronomist Ken Ferrie adds that vertical tillage done in the fall needs to be followed with a vertical tillage leveling pass the next spring before planting in order for the practice to be effective.

Seeing is believing. To show farmers that compaction is present in their fields, Mutz likes to use a soil probe.

"A lot of farmers are in denial and tell me they don’t have compaction. I tell them they’re full of crap," Mutz says, with a good-natured chuckle.

The soil probe quickly determines who’s right. If a horizontal layer is present, Mutz usually finds it at roughly 8" deep. He often likes to hand off the soil probe to farmers to find and feel the hardpan for themselves.

"Few corn roots are going to penetrate a hardpan," Mutz contends.

Most of his customers agree, once they see compaction for themselves. Some don’t, he acknowledges, noting: "There are guys out there who won’t believe it exists no matter what."

Those growers lose out on increased yield potential and, ultimately, more money in their pocket. Yield losses due to compaction in tracked areas can range between 10% and 20%, notes Mark Hanna, Iowa State University Extension agricultural engineer.

Knowing that compaction is an issue and then correcting it can boost yields. "I have one farmer who’s seen a 14% increase in his corn yields," Mutz reports.

Those kinds of results convinced Mutz to start helping more of his customers implement vertical tillage. In Huysman’s case, he began running a Great Plains Turbo-Chisel between 10" and 14" deep in affected fields in the fall to get below the hardpan that was present and shatter it.

"The ground isn’t superdry with the manure, but we are able to get the shatter effect because the plow has shanks close together with shark-fin points on them," he explains.

Complete, full-bore shatter between the tillage tool shanks and also between passes is needed to make vertical tillage effective, according to Ferrie. He says farmers might need to make their passes closer together when using vertical tillage, especially in a dry year like this one.

"Stop equipment and dig in the soil between passes from time to time to make sure they aren’t creating a ripple effect," Ferrie encourages. "If you typically make equipment passes within 24" of each other, you may need to reduce those passes to within 15" instead," he adds.

Expect to use more fuel when implementing deep tillage because the process creates more pull for the tractor, Huysman cautions.

"It requires 5 gal. more per hour when I’m crossing 12 acres an hour," he reports. The additional costs are more than offset by the yield gain.

When to wait. Ferrie notes that now is a good time for tillage, especially where compaction already exists.

"Dry soils help you get good fracture," he says. "We have some pretty good-sized basketballs out there that need to be sized down so Mother Nature can freeze and thaw them this winter and help us out."

However, Ferrie says, those farmers who have received considerable moisture lately might need to delay deep tillage until their soils dry in order to get the traction they need and the shatter they want.

Tillage in wet soils can quickly create or compound an existing compaction problem, says Randall Reeder, Ohio State University (OSU) Extension agricultural engineer emeritus.

"Compaction in wet soils destroys soil structure," he explains.

Ferrie adds that not everyone is experiencing compaction in their fields this year as a result of the drought. In Illinois, for example, collapsed soil seems to be more of a problem.

"The more clay in the soil texture, the more likely it is to collapse under drought conditions," he explains. "Farmers with sandy to sandy silt loam soils in this area, which may not have collapsed, are in pretty decent shape."

Furthermore, Ferrie says, while vertical tillage is useful to many farmers, not everyone benefits from it.

"We don’t need it in a good no-till or strip-till program that has no horizontal layers," Ferrie says.

Sidestep compaction. Conservation tillage practices and traffic management need to be the main strategies to avoid soil compaction. Hanna’s advice: Till only to the depth needed to break up compacted layers.

In addition, farmers need to evaluate their field operations that might have caused the compaction and attempt to avoid those practices in the future. Otherwise, soil can be recompacted to the depth of the tillage used.

OSU’s Reeder is a proponent of controlled traffic and no-till practices.

"Firm, no-till soil resists compaction," he says, noting that "the first trip across loose soil with a heavy axle load usually contributes roughly 75% of the total compaction."

Regardless of the tillage practices used to eliminate compaction, the first step is to realize and accept a problem exists, says Empire Tractor’s Mutz. His advice: "Invest $49 in a soil probe and take care of compaction before you lose your shorts and your yields."

Soil compaction is a problem for corn growers to varying degrees across the country, says Mark Hanna, Iowa State University Extension agricultural engineer. "The problem occurs in fields when soil aggregates and particles are compressed into a smaller volume," he explains. "As soil is compacted, the amount of open pore, or void space, decreases and the density, or weight of the soil per unit volume, increases measurably."

Soil density increases naturally with depth. "Soil below the surface is naturally more dense than the surface layer because it supports the weight of overlying material," he says. "Excessively compacted soil results in prob-lems such as poor root penetration, reduced internal soil drainage, reduced rainfall infiltration and lack of soil aeration from larger macropores." Practical information on how to identify and address compaction issues is in Hanna’s recent booklet, Understanding and Managing Soil Compaction.