High Surface Tillage

by David Heckendorf

The preparation for planting of a harvested eucalyptus plantation is a very important phase of the overall project. A major portion of the cost of 2R site prep should be expensed against the crop that has been harvested. Even if the land is not going to be replanted, the coppice regrowth must be dealt with and the sooner the better. The cost of growing a second crop of timber by selecting a coppice stem from the regrowth from each stump will be uneconomic. It is barely economic in third world countries with low labour coats and impossible in Australia.

The cutover site must be treated mechanically and there are various options open to the forester to achieve an economic replant or to return the site to pasture or agriculture. These options will be very limited if the site was not cleared completely prior to the first crop, e.g. if old growth stumps were left in place), or if the harvest operation has left very high stumps. “The secret of economic second rotation site preparation is in the supervision of the harvesting operation, to ensure low stump height and total wood utilisation”. Write this up on the wall, it is very important.

The method selected to site prep 2R eucalypt sites will be dictated by factors such as stump height, level of residual logging debris, coppice regrowth control, presence of old growth stumps and the possible restriction on burning debris.

This forestry rake sold to the DPI Queensland in 1987 is still performing well on a daily basis, raking over 35-year-old pine tops on a landing near Gympie, Qld.

Stumps: High stumps and runaway coppice regrowth can only be handled adequately by a Vee-Shear. The v-shear is probably the most common implement used in the US forest industry. The is a place for at least one in both WA and Western Victoria. Where sites have to be converted from eucalypt to pine, or where there is change in row width, the only really effective method of preparing the site for a new layout of mounds is to shear off all the old stumps at ground height. The entire site can then be raked with one of the big Savannah rakes and then re-mounded to the new spacings. The stumps size will dictate that a 300hp bulldozer is used to ensure there is enough power to cut through some of the well-grown stumps. In light sands, a wide grouser on the track will give better traction.

Coppicing: The most accepted method of killing coppice regrowth is to cover the stump with soil. It is obvious that the higher the stump, the more soil will be required to cover the stump. Savannah plows are quite capable of mounding over the stump line. Depending on the average stumps height, either Magnum or Tomahawk stump-jump plows could be used. The best configuration will probably be a 206 Tomahawk, with one or both the inside jump arms removed. A worn 32” disk would be used if this inside jump arm is left on. The middle jump arms should be fitted with new 32” disks and the back two jump arms can be fitted with 36” disks, to ensure that maximum bed height is achieved.

Savannah Model 1020 V-Shear fitted to a 300hp Cat D8K dozer, cutting off old coppiced eucalypt stumps. Pinheiros, Portugal.

   Debris: In order to achieve an acceptable level of bed quality, the high levels of debris left from field-processing must be removed from the strip to be bedded. This can be removed by using a fixed rake on a dozer, loader, or excavator, or by a Savannah Rotary rake. Raking with a dozer or loader is inefficient because of the presence of stumps; it is hard on the machine and even harder on the operator and as well as moving all the nutrient rich fines, also tends to deposit a lot of topsoil in the windrow. Using an excavator rake is slow, but can be the only practical method when working in small blocks on steeper land.

   The Savannah Rotary Rake is ideal for raking large areas of logging debris, as it will efficiently rake the debris over the stumps without dropping any material and it can be set to leave a layer of fines on the ground for nutrient replenishment. Windrows put up by the Savannah rake do not have any soil in them and so will burn easily and thoroughly. This can be a very important consideration in a wet environment.

   Harvesting: The most important member of the team involved in site prep is the harvesting supervisor. It is vital that he is aware of the latest harvesting techniques in the world; particularly in USA, where the industry is economics driven and responds very quickly to successful new ideas because the return to the company is immediate. The supervisor must be sympathetic to the site prep operator, so that the two operations are totally compatible. A stump height that is too high for either stump-jump plows or the rotary rake concept, means this highly efficient equipment cannot be used until the height is reduced by shearing, or loggers going back in to lower the stump heights: all at an extra cost. A few extra dollars paid to the logger can save literally hundreds in later site prep costs. Always aim for a 4” stump height and with equipment such as today’s ‘hot saws’, this is now easily achievable.