A new trend in tillage

by Mary Lou Peter

There´s a new trend in tillage equipment called "vertical tillage" and a Kansas State University scientist says it could also be described as "mulch till."

"The main objective of using vertical tillage is to break up surface soil compaction, or smooth out areas in a field with shallow (two-three inches) rills from water erosion or ruts and tire tracks from tractors, combines, grain carts, trucks, and other equipment," said DeAnn Presley, soil specialist with K-State Research and Extension. "It also is used to help improve rainfall penetration by breaking up crusts."

Vertical tillage equipment is used to lightly till the soil and cut up residue, mixing and anchoring a portion of the residue into the upper few inches of soil while still leaving large quantities of residue on the soil surface. This action helps speed residue decomposition, Presley said. The best description for vertical tillage is to call it a form of mulch-till, as it generally leaves more than 30 percent residue on the soil surface, yet creates nearly full-width disturbance on the soil surface.

However, Presley said, if a hard rainfall occurs after the vertical tillage operation on a low-residue environment, it could have the opposite effect. Vertical tillage should only be used when the soil is dry enough to shatter; otherwise, it may create shallow compaction. This type of equipment tends to leave the soil somewhat fluffy, but not to the extent that a tandem disk will.

Several companies manufacture vertical tillage equipment, and none of the implements is exactly the same, although there are common features, she said. From a distance, many vertical tillage tools look similar to disks in that there are a series of round blades in a gang on a toolbar. However, some models have blades individually mounted on springs, similar to a field cultivator. Offset disks are primarily used as primary tillage tools and tandem disks are usually used as a finishing tool. In contrast, most vertical tillage implements are used as a one-pass operation directly on crop residues prior to planting.

One of the physical differences between the two types of implements is that tandem disk blades are more curved, go a little deeper into the soil profile, and turn up some soil as they go across the field. Vertical tillage blades are generally straighter, more like coulters, and are often fluted. In fact, many manufacturers refer to the blades on vertical tillage implements as coulters. The degree of curvature and amount of fluting on the coulters varies by manufacturer, as does the angle of the gangs.

The blades on vertical tillage implements typically go only a few (two to three) inches into the soil, and do not move much soil as the implement goes across the field. Vertical tillage implements have a slight to moderate smoothing effect, which is usually enhanced with smoothing bars, harrow tines or rolling baskets behind the disks, Presley said. Again, the features available vary by manufacturer.

Tandem disks create more draft and have a somewhat higher power requirement than vertical tillage equipment. Producers using a vertical tillage implement can usually go faster across the field, up to six to seven miles per hour, than when using a tandem disk.

"At K-State, we have begun to evaluate the effect that vertical tillage on corn stalks will have on subsequent soybean yield, soil bulk density, soil aggregate stability and water infiltration on various soil types in northeast Kansas," Presley said. "We have just one year´s preliminary data, working with David Hallauer, who is the Meadowlark District Extension agent. We need more data, from different types of soils and conditions, and on different initial residue levels, before drawing any conclusions."

She noted that K-State agronomists tested one model in 2009, but that they plan to test other models and types of vertical tillage implements in the future.

More information, including photos of examples of vertical tillage equipment is available on the K-State Agronomy Extension Website at:

www.agronomy.ksu.edu/extension and click on e-Updates/current topics.

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