Disks used in brush control are heavy-duty with two gangs of disks. Offset disks chop and turn under surface debris and uproot shallow-rooted, sprouting brush species. They consist of two gangs of disks set at angles to each other. Each gang has a separate frame and axle assembly. On some models gang angles can be adjusted for varying soil conditions or desired disking action. Blades may be notched or straight edged and vary from 24 to 36 inches in diameter. Disks range from 8 to 15 feet in width and require tractors with 70 to 350 drawbar horsepower. These disks usually have rubber tires that are raised and lowered hydraulically for transport or depth control. Disks without wheels are hinged and they must be transported on trailers.
Disks with 36-inch blades are used for brush control on undisturbed soil while units with blade diameters less than 30 inches are used for seedbed preparation following rootplowing. In both situations, disks bury much of the surface brush debris and form a desirable seedbed (see the Offset Disk section of the Site Preparation chapter). Most disks used on rangeland employ notched disk blades to chop and bury debris. Disks can be used on a wide range of soil conditions and moderately rocky soil, but they cannot be used if there is excessive timber or rock. Farm-type disks are not suited for the rigors of debris-littered rangeland.