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Corn+Soybean Digest

Planting with Perfection

A Thompson sub-machine gun fires 18 bullets a second. That's the same speed most corn growers sock kernels into the ground every spring.

“Today's planters are shooting seeds into the furrow at the rate of 16-19 kernels a second,” says Kevin Kimberley. The former corn grower from Maxwell, IA, uses his farming and equipment experience to consult with growers across the country, especially in the Midwest.

“If anything in that row unit is off by just a fraction, it leads to skips, doubles and triples,” he says. “That costs farmers big money in poor germination, uneven stands and yield losses.”

Kimberley says keeping the planter's row units in excellent condition can cut yield losses by 5-30 bu./acre. At today's corn prices, that's $20-120/acre more profit.

In 2007, he logged more than 50,000 miles delivering his accuracy message. Farmers hire him to troubleshoot planter problems in the field and set up tillage systems to marry tillage practices, like strip-till, to the planter. He also makes presentations to county corn grower associations and trains equipment dealers on planters.

“OFTEN, THE BEST advice I can give is what not to do,” Kimberley says. “That's because all farms are different, so information has to be customized to each situation. It's not about bushels, it's about dollars. Where you can save money is as important as going after more bushels.”

He says the biggest planter problems he sees are skips, doubles and triples.

“These reduce yields so you have to start with singulation and make sure your system is operating properly. When you check row units, number each one and make sure to replace all worn parts. It's not the newest planter that always produces the best results,” he says.

As an example, he shows a photo of near-perfect plant spacing that was accomplished with his oldest planter, a 1981 finger pickup model with all-new row unit parts. “When you inspect the row units, check fingers and backing plates for rust and wear, check drives and idlers, replace bushings annually and remove and inspect the belt,” he explains.

On all planters, he recommends checking the disk openers, seed tube, cast frog, gauge wheels, press wheel, brackets, drive chains and idlers.

On vacuum planters, remove and check the seed plate and make sure to size the seed to the disk. “You need to be careful to change disks and match them to seed sizes,” he says. “You can save up to 30 bu./acre in yield loss by changing disks when you change seed sizes.”

Number all row units and their respective disks. Mark the hub to make sure the disk goes in the same way each time. Kimberley recommends using Precision Planting “E” sets in vacuum planters.

DON'T STOP WITH the row units, advises John Smith, professor and Extension agricultural engineer at the University of Nebraska's Panhandle Station in Scottsbluff.

“You need to check the planter drive and also your seed tubes,” he says. “You can have the metering unit tuned up, but if the drive system is not performing properly, you won't get the results you think you're going to get.”

Smith has focused his research on improving the plant spacing accuracy; first in sugar beets, but also in corn and other crops. With a colleague, Smith developed an electronic testing machine that accurately measures individual seed spacing. It's used to check spacing accuracy on some 1,000 planter rows every season.

The seed spacing sensor is placed at the bottom of the seed tube and uses lights and sensors connected to a computer software program to accurately record individual seed spacing.

“If you have uneven spacing, be sure to check the planter drive,” he says. “Make sure all sprockets and chains are meshing right, and replace any that are worn. A bearing that is sticking, for example, can create uneven spacing because the seed plate is not turning uniformly and consistently.”

Smith says the entire drive system — because of its many parts — is critical to spacing accuracy and is often overlooked during a planter checkup. “The drive must turn smoothly and evenly with no jerking,” he adds.

ACCORDING TO SMITH, the seed tube also plays an important role in spacing consistency and uniform stands. “The seed tube is a wear item,” he points out. “The front inside surface must remain glassy smooth. If it's worn, the seed will contact it and hesitate. Sometimes the seed will zip right down there, but other times it will slow and that gives you an uneven stand.”

Pull the seed tube and put your little finger on the front surface where the seed slides at the bottom. If it feels glassy smooth, you're fine. If it looks or feels like worn sandpaper, replace it.

“With a good seed tube, each seed will take the same path to the furrow, and will take the same amount of time for more accurate spacing,” Smith says.

Both Smith and Kimberley agree on planter monitors. “They're very good at giving you accurate information on average seed population and average seed spacing,” says Smith. “But, they will not give you any information on individual seed spacing.”

According to Smith and Kimberley, the Precision Planting 20/20 Seedsense, released about a year ago, is the only monitor today that measures individual plant spacing and reports down pressure and planter ride.

KIMBERLEY SAYS MANY growers now plant seed treated with insecticides, and need to add ¼ cup of graphite on finger pickups and ¼ cup of talc graphite mix on vacuum planters mixed thoroughly per bag of seed. This improves flowability through the row unit.

He also emphasizes leveling the planter to obtain consistent seed depth, and making sure trash wheels, coulters and closing wheels are set properly to eliminate sidewall compaction.

“The best way to tell if your planter is running level is to hop on the four-wheeler and drive alongside while it's in operation,” he suggests.

Another tip: Pay close attention to the weather and during a dry year fill the planter box; during a wet year add only one bag at a time. This will help achieve a uniform planting depth with less sidewall compaction.

His tillage tips include field cultivating in the same direction you plant and operating the field cultivator at high speeds — up to 8.5 mph to reduce compaction and dig out root butts in corn-on-corn rotations, leaving them on top of the soil.

He advises growers that at the end of the season, don't just back the planter into the shed and leave it. Take the row units apart, clean them and store the working parts in a plastic tub. Place them in a dry area with consistent temperature to fight rust and you'll get longer use from your planter.

“Many of the helpful things I learned were by trial and error,” Kimberley says. “But accurate planting is the most important thing you can do to reduce yield losses.”


The University of Nebraska designed an electronic measuring system, similar to those used in Europe, to accurately measure seed spacing. It uses a PhotoGate: a small, flat device with a hole about 3 × 3 in., which is placed below the seed tube. It has 24 openings on each of the four sides of the hole. Each opening has a light emitter with a sensor on the opposite side.

When a seed passes the opening, it blocks the light from one or more of the sensors and sends a signal to the computer. Special instrumentation software records the time each seed passes through the opening and where it went through — forward, backward or side to side.

The computer converts that time into a distance, correcting for the position of the seed, then accurately reports the spacing between individual seeds.

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