Two edge profiles cover ~95% of disc harrow blades: notched and smooth (also called "plain"). They cut differently, wear differently, and pull differently. Here's when each earns its spot.
Notched blades — aggressive residue cutter
Notches along the outer edge act like teeth. They grab and chop tough residue instead of skating over it.
Best for:
- First pass through heavy corn or cotton stalks
- Cover crop termination (rye, oats, radishes)
- CRP or grass sod breakup
- Front gang on offset discs — where residue is thickest
Trade-offs:
- Notches wear faster than a smooth edge — expect ~15% shorter life
- Slightly more draft (tractor HP demand)
- Rougher finish — leaves a coarser seedbed
Smooth blades — cleaner cut, longer life
A plain edge slices through soil without grabbing. Used where residue is manageable and the goal is a fine, level tillage pass.
Best for:
- Rear gang on offset discs — after the notched front gang has chopped
- Secondary tillage / seedbed prep
- Light residue conditions (soybean stubble, fall tilth)
- Vertical tillage tools
Trade-offs:
- Poor performance in heavy trash — skates over instead of cutting
- Not ideal for tough sod breakup
Mixing them on a disc harrow
Standard practice on tandem and offset discs: notched blades on the front gang, smooth on the rear. Notched breaks up residue, smooth smooths the seedbed behind it. This gives you the residue-handling of notched with the finish of smooth on one pass.
On a vertical tillage rig, you'll often see all smooth blades because the goal is speed, not aggressive residue cutting.
What about wavy or ripple edges?
Wavy and ripple blades are typically coulter blades, not disc harrow blades — they mount on no-till planters and drills to slice a slot for the seed unit. See our Coulter Blades Explained guide.
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