High Surface Tillage - Forest Products Equipment February 2002 Issue

Forest Products Equipment - February 2002 Issue

A perfect site prep approach?

by Kristina Stewart
and Mark Sauer

It is doubtful that any one piece of equipment provides the perfect site prep solution for today's economically driven timber market. Currently all sectors of the market are challenged to provide extremely efficient forest operation services with the greatest return based on timber yields realized 18 to 30 years from now. New high tillage combination and bedding plows offer a more versatile and perhaps cost effective approach.

Mechanical tillage
Site prep contractors, consultants, equipment companies and landowners are faced with providing the greatest rate of return on their varying forms of investments in the timber market. Site prep, though only a small portion of the timber cycle, is most important and analogous to the principle of building your home on a firm foundation. The initial gains in survival and seedling vigor are fundamental to improved growth over the life of the rotation – “you sow what you reap.”

Wes Stone of Reynolds Forestry Consulting commented that many people select site preparation like buying groceries at the supermarket. He says, “Unfortunately, there are consequences for doing so. One lost year due to failed plantation establishment attempts can result in lost opportunity costs of approximately $320 per acre per year!” He concludes that high intensity site preparation involving tillage “not only ensures greater survival but also provides accelerated growth rates, while at the same time decreasing risks and increasing rate of return.”

Developments towards new technology
   There is considerable confusion around which is the best technology required to provide the greatest return. The Buzz for years has been about subsoiling: digging deep into the lower strata of soil to improve seedling root growth and moisture retention of the soil. Reduced timber pricing has resulted in more selective application of this practice with much talk of the need for “greater tillage” or “finer tillage” on the surface with bedding plows.

   Currently, many site prep prescriptions that traditionally required subsoiling are now combining treatments with bedding where there are questions as to weather soil compaction is a condition. As a result, the contractor is faced with having to run subsoil plows and bedding plows on one site. As subsoil plows produce a bed over the rip line of the subsoiler, many contractors remove the rippers on certain areas of a tract where only bedding is desired. This is less expensive than investing in another plow.

   Another result of this practice has been determining what, if anything, should replace the center tillage that subsoil shanks provide. Wider inner disk spacing on subsoil plows result in a loss of center tillage when the ripper shank is not engaged. As a result, center tillage is a concern with bedding, as well as subsoil plow prescriptions.

High surface tillage
   With much feedback from contractors, consultants and forest researchers, new bedding plows are being introduced that promote finer tillage with less creation of clods. The disk geometry on fine tillage plows is less aggressive, in that the lead (angle of the disk to line of travel) is reduced and there is less spacing between the disks to produce a finer tillage effect. This innovative disk geometry also results in the new generation of high tillage plows pulling with less resistance.

   Mark Sauer, president of Savannah Forestry Equipment states, “With the introduction of our Tomahawk high tillage plows, we found an additional feature is their ability to run on lower horsepower tractors. A good example of this is our six-disk Tomahawk bedding plow. In its standard configuration, it runs on 140 to 190 horsepower tractors or skidders, whereas a standard six-disk Savannah plow would traditionally run on a 250 to 300 horsepower tractor.”

The Tomahawk jump arm technology allows 34 inches of clearance under disk when in the up position, allowing trash to flow through the plow and not clog between disks. This also leads to lower drag on the pulling machine and a lower level of maintenance.

One great feature of high tillage plows is their versatility. The plow frame that supports the jump arms and disks can be adapted for mounted or trailing, bedding or subsoil plows. Many contractors are able to retrofit their existing plow with a Tomahawk high tillage frame for a low cost compared to purchasing a complete new plow. Sauer notes that subsoil plows configured with high tillage bedding characteristics enable a reduction in the depth of subsoiling, with thorough tillage.

Center tillage
Numerous conversions with contractors and foresters resulted in lengthy discussions and questions about center tillage. Is it required? How can it be achieved? Is it mechanically sound? Can debris flow through the inner disks?

One certain way to reliably achieve center tillage is to continue using the subsoil shank found on combination plows. Subsoil shanks are now being manufactured so that the depth of penetration can be adjusted from 10 to 12 inches. This approach requires more horsepower than a relieving disk configured to till the center of the bed, but eliminates the expense of purchasing completely new equipment

Many equipment suppliers have tried to address the issue of center tillage, and Savannah has just introduced a new series of plows that takes advantage of overlapping disks and tomahawk jump arm technology. Sauer notes, “I have seen the old “Center Buster” approach produced by Rome Plows years ago, several times in the last month.” Savannah’s approach provides center disks which have been spaced close enough to completely remove the soil in the center of the bed and the outer disks brings this soil back to the center.

“When you see this plow running, there is a tremendous amount of energy that pulverizes the soil and leaves a double tilled zone in the center of the bed.” Sauer refers to this as “overlapping tillage” much like disking, but in a concentrated zone that becomes part of a mound. Like the standard Tomahawk plow series, the 260 Series overlapping tillage plows are available in bedding and combination plow configurations and can be retrofitted to existing plows.

Though the answers to when these various methods are required is now always clear, it is apparent that the emphasis on tillage today challenges most anyone associated with site prep. It is encouraging that there are realistic approaches, weather involving new equipment or adapting existing equipment, that enable this less known area of the forest industry to develop with market needs.