How to Tell When Your Planter Disc Openers Are Worn Out
Worn openers cut a W-shaped furrow instead of a V, and that leaves air around the seed. Here's what to check and what to replace them with.
Disc openers are cheap next to what they cost you when they're shot. They also wear so slowly you can run them a season or two too long without noticing.
What worn openers do
Purdue explains it better than anybody. As each disc wears, its diameter shrinks and the two discs slowly move apart where they meet at the bottom. Instead of a clean V, they cut a W.
Closing wheels can't firm a W. That leaves pockets of air around the seed.
You want good seed-to-soil contact, not good seed-to-air contact.
That matters. Purdue also reports that emergence delays of about 10 days cut yield 6 to 9%, and it names worn disc openers as one of the causes of delayed emergence.
What to check
- Diameter. Precision Planting's number for John Deere discs is 14.5 inches. Its planter specialist Clay Scott calls even 14-5/8 junk if you're putting 100 row acres a year into heavy no-till with no coulter, though it may get you by at 30 row acres on tilled ground. Other makes, check your manual.
- Bearings. Grab the blade and rock it. Any play is too much.
- Alignment. Openers and coulters need to line up.
- Seed tube guards. Replace at 3/4 inch wide, or 0.64 inch on a SpeedTube guard. A worn guard lets the discs flex in and pinch the furrow, which can change your depth.
- Gauge wheel arms. Worn ones let depth wander.
Check them on the concrete in the off-season, when it costs you nothing but a morning.
What to replace them with
Wearparts' Guaranteed True assemblies come in most common sizes. A few we can get:
- John Deere XP: 15 in. x 3.5 mm, replaces AA65248 and AA105716
- John Deere MaxEmerge: 15 in. x 3.5 mm or 3 mm
- Kinze: 15 in. x 3.5 mm
- Case IH 1200 Series: 14 in.
- Case IH 2100 Series: 15 in. x 4.5 mm
- Great Plains: 15 in. x 4 mm, or 13.5 in. (also Krause)
- White: 13.5 in.
Not sure what you've got? Text a photo of the part with your make and model.
See the full list on our disc openers and wear parts page. Sources: Purdue, Stand Establishment Variability in Corn, No-Till Farmer on disc openers and Precision Planting on seed tube guards.