Notched vs. Smooth Disc Blades — When to Choose Which

John Deere tractor pulling a red disc harrow through Iowa cropland

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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Frequently Asked Questions

What's the difference between notched and smooth disc blades?
Notched blades have scallops cut around the edge that grab and chop residue aggressively — ideal for cutting through cornstalks, heavy trash, and hard ground. Smooth blades have a clean, uninterrupted edge that cuts cleaner and moves less soil, better for secondary tillage and seedbed prep.
Which disc blade is best for cutting cornstalks?
Notched blades. The scallops bite into stalk material and slice it as the gang rolls, where a smooth blade would just push the stalk aside. Most operators run notched on the front gang and smooth on the back gang for exactly this reason.
Can I mix notched and smooth blades on the same harrow?
Yes — mixing is standard practice. Notched on the front gang for aggressive residue cutting, smooth on the back gang to finish and level the seedbed. Just don't mix within a single gang unless the machine spec calls for it.
When should I choose smooth disc blades?
For back-gang duty on a tandem harrow, seedbed prep, closing passes after primary tillage, or lighter ground where you don't need aggressive residue action. Smooth blades wear more evenly and cost less to run per acre if the soil doesn't demand a notched edge.
Do notched blades wear faster than smooth?
Slightly. The scalloped edge concentrates wear on the peaks between notches, so notched blades typically show wear a season earlier than smooth blades under similar conditions. Not a reason to avoid them — just budget for a slightly shorter replacement interval on the front gang.