Vertical Tillage - The Real Truth
There is probably no hotter topic in the farm equipment industry today than vertical tillage. Since the 1990’s, when soil density effects were studied and the term “vertical tillage” was coined, there has been an ongoing erosion of what the term really means. It has come to the point that there are numerous machines on the market that are sold as vertical tillage that do not meet the criteria of what vertical tillage is all about.
To address this issue, one needs to understand that vertical tillage means that the ground engaging components of a given tool enter the soil in a vertical rather than horizontal fashion. Conventional “horizontal” tillage implements, such as disk harrows and field cultivators, create horizontal compaction or stratification layers in the soil. These density changes inhibit root growth, impacting crop stand ability and yields.
Machines that utilize straight (non-wavy) coulters running in the same direction of the machine or chopper reels essentially create no stratification layer. However, certain sacrifices have been made in the interest of penetrating hard ground and leveling the soil surface to create the desired seedbed for increased yields. The difficult discussion arises when the question is brought up as to how far away one needs to be from true vertical tillage to achieve the desired goal. Certainly, a slight angle and small concave on a row of discs increases penetration and coverage but the present market is now being asked to accept tools that have become yield robbing machines with multiple high angle disk gangs. While these machines may perform well as residue management tools, it is difficult to categorize many of them as vertical tillage machines.
The following drawing illustrates the difference in root structure in mixed soil vs. stratified soil.
Studies have shown significant yield increases when soil stratification is minimized.
These studies have also proven that “true” vertical tillage will minimize soil stratification. The key factor is minimizing the amount of contact area the tool makes as it passes through the field. By keeping the angle of attack as shallow as possible, and the space between each blade as wide as possible, the percentage of stratified soil is greatly reduced. For example, each 20” diameter disk blade with 5/8” of concavity set at a 1-1/2” soil depth creates a contact area 1-1/8” wide when the disk gang angle is set at 5º. That same disk blade set at the same depth will create a 2” contact area with the disk gang angle set at 10º, and a 3-3/8” contact area when the gang angle is set at 18º. Obviously this effect is magnified when blade spacing is narrower, as is the case with double disk gang machines.
Unfortunately, recent machine introductions by various manufacturers have followed the double disk trend. Using a vertical tillage system has been proven to be a valuable component in today’s farming practices. We also believe that no single tillage machine, including our own Reel Disk, can be referred to as a “system”.
We believe that an educated farmer is a profitable farmer. We encourage you to take the time to understand what vertical tillage really is and what advantage it may or may not have in your operation. Hopefully, this article will clarify what vertical tillage is and that you are buying the tool that’s right for you.