Disk harrows are for secondary tillage including weed control, incorporation of fertilizers and herbicides or pesticides, breaking up surface crusts and clods, and mixing and leveling the top few inches of soil. Disk harrow widths between 11 and 46 feet are towed implements with wheels that are raised and lowered hydraulically. Narrower width models attach to the 3-point hitch and are listed as accessories to landscape-size tractors (less than 75 horsepower). Large, wide disks fold for a suitable transport width. Blade diameters are 20, 22, or 24 inches and spacing between blades varies between 7 and 9 inches. Selected models are designed to traverse small rocks.
Disk harrows are seedbed finishing implements. They are lighter duty than offset disks and generally use smaller blade diameters and narrower spacing between blades. They are designed for clean-tilled land. Use of heavy-duty models is advisable when crop residue is present or for rangeland applications. Several attachments are available to smooth the soil surface for planting. These disks are very effective in removing weeds prior to planting and incorporating herbicides, manure, or crop residue. They are not designed for rough, rocky, or brushy conditions.