Land Clearing

Probably the best possible way to clear a forested area for agricultural use is in-place burning of whatever vegetation exists. Unfortunately, this is not easy to do because forest fires do not tend to cease burning precisely where one wants a field to end.

There is a substantial dollar value to the nitrogen, phosphorus, potassium, calcium and magnesium that burning can release from the organic matter on forest floors. In an article in the January issue of Agroborealis, Dr. Keith Van Cleve and coauthors estimate the cash value of these nutrients to be $133 to $235 per acre. That would be the cost of the commercial fertilizers required to replace the substantial nutrient drain if the forest floor is removed in the clearing process.

In the same issue of Agroborealis, a publication of the University of Alaska Agricultural Experiment Station at Fairbanks, Carol E. Lewis and coauthors describe some of the clearing methods used on a 2000-acre tract set aside for clearing trials at the Barley Project near Delta. According to their article, it appears that the closest approach to leaving the organic matter in place for burning is a method employing two large tractors dragging a heavy anchor chain between them. The chains come mostly from old Liberty Ships; the largest chain in use is 200 feet long with nearly a hundred 60-pound links. It weighs about 10,000 pounds. The chain is capable of knocking over sizable trees and in many cases dislodging the root crowns from the soil. Then another tractor equipped with a massive V-shaped blade, itself capable of shearing off trees up to 8 inches, is used to push the organic material into small, loosely packed and closely spaced windrows for later burning.

Windrows can be formed with the chain itself if a heavy object is fastened to its middle. For that purpose, a 4-ton iron ball has been used in clearing operations in the Peace River regions of Alberta. Glen Franklin, who works in the Barley Project near Delta, indicates that the chaining methods allow clearing at the rate of ten to twenty acres per hour.