A customer came in today and asked if disk openers that measured 14-3/8 inches in diameter were worn out, or if they would plant 1200 acres this spring. We recommend replacing disk openers when they reach 14-1/2 inches, but I told him, "Yes, they'll plant 1200 acres. The question is, how accurately do you want to plant those 1200 acres?"
That was probably a snarky way to answer his question, but it's important when prepping a planter to know what you want to accomplish. If you just want to put enough seed in the ground to grow a crop, worn out disk openers will put seed in the ground.
But I know for fact that variations in seed depth affect final yields. Seeds planted a half inch deeper or shallower than adjacent seeds emerge faster or slower than their neighbors. Farm Journal's Ken Ferrie has famously said any seedling that emerges 48 hours after its neighbor is a weed for the rest of the growing season. So, since disk openers strongly influence the quality, shape and depth of seed furrows, disk openers strongly influence emergence and eventually, yield. That's why we recommend replacing disk openers worn to 14-1/2 inches or less.
We aren't trying to sell parts when we get finicky about fractions of an inch on disk openers. If you tell me that you "...just want to put seed in the ground," then I'll help you do the least possible repairs as cheaply as possible to your planter. I'm also realistic and don't expect every customer to bring his planter to factory specifications every year--that would be exorbitantly expensive. I just try to find the middle ground that gives each farmer a planter that will do the job he finds acceptable for the money he wants to spend.
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