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Press

 

Carsten Brüggemann Hanover
Chamber of Agriculture
Niedersachsen, Germany
June, 06th, 2005

Clearing orchards in one work step
– woodchips as biofuel
– Introducing new chipper for fruit tree cultivation –

Cultivated fruit tree orchards are renewed on a rotation basis when the trees no longer produce the desired results. Procedures used hitherto are elaborate and involve distinct disadvantages, including soil structure problems. The complete removal of the biomass in particular has not been satisfactorily solved as yet. A newly designed chipper (the Jordan chipper) is a promising new development.

No procedure has so far been developed for uprooting fruit trees and at the same to time clearing the site in one work step. Whether the trees are manually felled with a chainsaw and then mulched, chopped up with a chipper, pushed over with a tractor and mulched several times or whether the material is removed from the soil, several work steps are always required. In some cases, stump grinders are also used or remaining stumps are pulled out with cultivators.

In the mulching procedure, felled or pushed-over trees are shredded and mixed with the soil. The wood chips are mixed into the soil at a width of about 40 to 80 cm. The high proportion of wood mass causes the soil to become acidic and leads to growth inhibiting conditions for subsequent crops. In addition, several work steps are usually required in which the site is worked 2 – 3 times in succession with a mulching machine thereby destroying the soil structure at a width of up to 2.5 m. Larger pieces of wood that were not fragmented by the machine may still need to be removed. Rootstocks and/or pieces of them remain in the ground.
In general, it is best to remove all of the material from the site so that sources of infection with bacterial diseases such as fire blight can be effectively prevented or controlled.
Chipper will completely remove the wood from the site, but the problem of feeding the material into the machine has so far not been solved satisfactorily. This often requires a time-consuming effort and driving over the orchard with several large machines which, depending on the weather conditions, can cause soil damage.
The newly introduced combination chipper is a special disc chipper that was equipped with a special hopper chute unit for direct feeding of standing orchard trees.

Ernst Jordan from northern Germany developed a hopper unit with which a chipper is capable of pushing over orchard trees and chipping entire trees along with their roots. Even existing stakes, wire cylinders or plastic ties can be chipped along with the trees. Depending on the intended use of the wood chips produced, these items may have to be removed from the mass, particularly if the wood chips are intended for use in heating plants where such debris is are not tolerated.
The basic unit of the "Jordan chipper" is a special disc chipper by Jensen/Maasbüll. The machine chips trunks up to 25 cm in diameter; root masses can be of a larger diameter. A continuously variable adjustment permits wood chip sizes ranging from one to 40 mm.
The chipper is attached to the rear of a reversible tractor. First, the fruit trees are pushed down with a horizontal cylinder located on a hydraulically adjustable frame about 1 - 2 m in front of the chipper. A horizontal pin-feed drum, which rotates below it up to 10 cm into the soil like a tiller, grabs the root of the pushed-over tree, pulls it out of the ground and feeds it to the vertical in-feed drums. These can be extended laterally and can thus be adapted to the thickness of the material being fed into the machine. The unit's cone-shaped design means that they do not have to be completely opened when thicker stumps are gripped in the lower section. The drums are driven hydraulically and develop an in-feed force of about 3 tons. Behind the cylinder and drums there are three additional horizontal rollers, through which stones, sand and other debris can fall. This helps prevent unnecessary wear and tear on the chipper knives caused by debris. The in-feed speed to the feed drums can be infinitely adjusted.

In the event the in-feed units are overloaded they are temporarily switched off. This prevents a large decrease in torque and less stress on the tractor engine. If the unit gets clogged, the direction of the in-feed components can be reversed with a reversal unit on the tractor to remove the back-up.

Since it is difficult for the tractor driver to observe the in-feed area directly, a wide-angle camera is attached to the front drum frame, which provides the driver with a generous view of the entire in-feed area.
During the past few months, the machine was tested in the northern German fruit growing region of "Altes Land“ under extreme conditions. After a rainfall of approx. 60 mm in 5 days, at times the test was like a mud fest (see photos), but brought acceptable results nevertheless. "If the machine works flawlessly under these conditions, where in addition to the wood, we feed piles of dirt through the chipper, I can't see any problems under normal conditions," says design engineer Ernst Jordan enthusiastically about the fine performance of his machine.
Depending on the moisture content of the wood, the chipper disc's two knives have to be removed for sharpening one to two times per week when the machine is being used at full capacity. Due to the high level of sand content experienced during the test, the knives had to be exchanged after two days. The time required for this operation is less than half an hour. The machine has four grease nipples and this is all there is to maintenance.


Clear advantages of industrial engineering

Mulching takes place at running speeds of 300 to 400 m/h. In addition, 1 to 2 repetitions are necessary. Chipping, on the other hand, requires only one work step. With sufficient tractor performance (a min. of 135 kW) operating speeds of 1 to 1.2 km/h can be achieved. The wood chips produced can either be blown out over the site or collected and used in gardening and landscaping activities or as fuel. Depending on the age and size of the stand, about 80 – 100 m3 wood chips per 2½ acres can be accumulated. At a yield of 100 m3 the accumulated wood mass corresponds to a quantity of fuel oil of about 7,500 l.

Collecting the wood chips during mobile deployment is another problem when no separate vehicles are allowed to drive on the orchard. For this purpose, a container with a capacity of about 5 m3 can be attached to the tractor. The wood chips are conveyed over the tractor to the container with an ejector. A high dumper unit permits the transfer of the wood chips to the transport trailer without losing much time. The use of perforated steel sheet serves to limit the weight of the container.
The machine was introduced with a Fendt 930 VARIO TMS at 220 kW and reverse gearbox, which is a prerequisite for using this machine. It is possible to use smaller tractors but they should not have an output of less than 135 kW in order to permit the smoothest possible performance and reasonable area coverage.
"We consider the procedure technically and economically very interesting and will purchase and use the machine," is the assessment of private contractor Theis Pape, on whose orchards the machine was tested. The Jork fruit growing, experimental and consulting centre is also watching this development with great attention. "Clearing orchards this way in one work step and at the same time leaving a clean site is effective and interesting. The price of the machine and the procedure will have a decisive impact on how widely it will be distributed," says Dr. Matthias Görgens from Jork.
Series production of the machine has started. Even if the exact price has not yet been determined, depending on capacity utilization, clear cost advantages can surely be expected in comparison with other vehicles. A worldwide patent for the invention has been applied for.