In the fall all of these tools can be used effectively to break up residue and bring up soil to help warm up and dry out the soil in the spring. The straighter angles of the Great Plains and Salford tools will keep the largest amount of residue on the surface and create less soil disturbance. The thing to remember with the straighter angled tools is the horsepower requirement is often higher due to the weight needed to get the tool to penetrate. The angled gangs of the Kuhn-Krause, Landoll, and Case IH will provide the least amount of residue on top leading to an increased chance of erosion, but still less than a traditional chisel plow except the concaved blades on the Landoll VT Plus will be very similar to a chisel plow.
In the spring we have seen a different effect from using vertical tillage. The straighter angled tools will not provide a seed bed comparable to a finisher or field cultivator. In my opinion, these tools are merely a fall tool that will break up residue for decomposition and fit in a minimum till operation. The higher angled tools will provide a similar seed bed to finishers, but will tend to have more smear while not bringing up wet soil. I have seen two tools in the last two years give unacceptable levels of smear leading to a hard pan just below the depth of planting. This picture shows just what this did to the plants themselves. In most cases I can show you the direction of travel from the differences in height and stalk diameter of the corn plants.
So is vertical till a replacement for a soil finisher or field cultivator? It really depends on the soil types you are working and spring moisture levels. In our area the straight angled tools are strictly fall tillage and fit very well in minimum till environments that are heavy on corn in the rotation. The more aggressive tools can be used in spring, but need to be kept out of wet soil entirely. If you have noticed in the past 3 years manufacturers are pulling back on the depth of tillage as well with these tools. We have seen the recommendation go from 4" deep in spring and fall to 1.5-2.5" to keep this depth of smear to at planting depth or just above. With all of the scouting and digging I have done I would say that if you buy a vertical tillage tool you should keep your finisher or field cultivator, and watch soil moisture levels in spring. I would also consider using floating row cleaners on your corn planter as more residue is likely to be on the soil surface in spring.
If you are buying a vertical tillage tool consider HP requirements, angle of the blades, and disk blade types. The Landoll VT has been very popular here, but if you look at it next to a disk you would be hard pressed to tell the difference. At the 2012 Farm Progress Show in Boone, IA John Deere had a very nice demo about the smear layers each tool makes and the soil disturbance. Although, it was slightly counterproductive as it showed that the John Deere tool left a larger smear layer.
As we see more of these tools in the country we are seeing prices come down. I think they have a fit, but be careful how you plan to use them. If you are interested in them I would demo one and do some digging behind the tool in dry soil to see how it affects the soil and if it is fitting the purpose you need.
