In the movie, “Casablanca,” Captain Renault tells his police officers to, “Round up the usual suspects,” implying it’s easy to assign blame to frequent offenders even if they’re innocent in a particular situation. The same thing happens when planting.
Let’s say a planter’s seed monitor signals a planter malfunction, or ground-truthing uncovers problems with seed depth. Past experience leads the operator to suspect an issue with seed meters or gauge wheel settings, but inspection proves those “usual suspects” are blameless. That’s when it’s time to look deeper to find the actual, less-common culprit.
Such as:
Problem: Difficulty in maintaining desired vacuum. Vacuum fans are operating properly.
Uncommon cause and solution: Worn vacuum seed plates. Holes in seed plates may also be worn slightly oval rather than perfectly round. Replace worn seed plates.
Problem: Seed depth varies ¼” to 1” behind the planter. Examination of seed furrow between rear of disk openers and front of closing wheels shows crumbly seed furrow walls and loose dirt at bottom of furrow.
Uncommon cause and solution: Too much gap between gauge wheel tires and sides of disk openers creates poor seed furrow walls and encourages loose dirt to fall into bottom of seed furrow. Adjust gauge wheel arms to provide no more than 1/16” clearance between gauge wheel tires and the sides of disk openers.
Problem: Too many doubles and triples. Vacuum is appropriate for seed size; reducing vacuum creates unacceptable skips. No “sweet spot” for vacuum setting to give desired results.
Uncommon cause: Double-eliminators in seed meters are worn or mis-adjusted. On Precision Planting seed meters, make sure “knock outs” and double eliminators are up to specs. Worn brushes at the top of Great Plains AirPro seed meters can increase doubles and triples. On Deere and other planters, change the setting of double eliminators to expose more or less of the holes in seed plates, creating incrementally more or less vacuum to hold each seed, to find the sweet spot between too much and too little vacuum.
Problem: Unable to maintain desired seed spacing; can’t maintain Seed Release Index (SRI) values between 10 and 15 on Precision Planting 20/20 seed monitors, or Coefficient of Variation (CV) values below 0.17 on John Deere seed monitors. Individual seed meters have no mechanical problems and perform well when checked on a seed meter test stand.
Uncommon cause and solution: Rough ride due to uneven seedbed is disrupting metering accuracy. To confirm diagnosis, temporarily slow planting speed to 2 mph. If seed spacing indexes improve at slower speed, consider slightly lowering row cleaners to move more root balls and clods and provide a smoother path for seed unit gauge wheels. If possible, change adjustments on seedbed finishing tool to leave a smoother field surface.
Problem: All seed meters on a planter develop poor singulation after refilling planter. (See below for explanation of singulation.)
Uncommon cause and solution: Add-on seed treatments can compromise singulation. Try a sample of seed with a different coating in one row to diagnose seed treatment problems. To compare singulation performance in a bulk-fill planter, fill one seed meter mini-box with different seed. Increasing talc/graphite in seed hoppers may reduce problems with gummy seed treatments.
Seed Singulation Explained
Singulation is a measure of how accurately a seed meter dispenses seeds. Perfect singulation means one seed is dropped in every spot a seed should be dropped. If a planter drops two seeds in one spot and three in another, singulation is 95%.
Singulation’s effect on yield is population-sensitive.
“Hitting 95% singulation has more consequences when planting at higher populations” says Great Plains Manufacturing’s Blake Bergkamp. “Five percent fewer plants at 24,000 plants per acre is 1,200 plants, but at 35,000 that 5% is 1,750 plants. The higher the planting rate, the more singulation affects final population.”
While 100% singulation is always the goal, realistic singulation rates vary between different styles and brands of seed meters.
“Our Precision Planting vSets can singulate between 98% to 99%,” says Precision Planting’s Bryce Baker. “Mechanical finger pickups, depending on seed size, can vary from 94% to 99% singulation. Vacuum meters, if adjusted properly, can consistently singulate at 98% to 99%.”
Dan Anderson uses his hands-on experience with farm machinery repairs, field operations and technology to share practical tricks and fixes.
