Offset disks chop and turn under surface debris, breakup shallow compacted layers, till, and uproot small woody plants. Offset disks 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 22 to 28 inches in diameter. Some models are designed specifically for rocky soil. Offset disks range from 6 to 22 feet in width and require tractors with 70 to 300 PTO horsepower. These disks have rubber tires that are raised and lowered hydraulically for depth control or transport.
Offset disks are used for primary seedbed preparation where small to medium amounts of debris and vegetation are present. Blade diameters larger than 30 inches are used for brush control on undisturbed soil (see Offset Disk section of Mechanical Control). Disks are a popular method of tilling soil from a depth of a few inches to 9 inches for revegetation projects. 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 woody debris or large rocks. If brush debris is not present, then rubber-tired tractors are used to pull the disks. These disks are marketed as heavy-duty farm units.
References / Additional Information
Stevens, R.; Monsen, S.B. 2004. Chapter 9. Mechanical plant control. In: Monsen, S.B.; Stevens, R.; Shaw, N.L., comps. Restoring western ranges and wildlands, vol. 1. Gen. Tech. Rep. RMRS-GTR-136-vol-1. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 65-88.
Wiedemann, H.T. 2007. Sculpting brush mechanically: Current state of the art. Rangelands. 29(5): 10-17.