I know the weather hasn’t seemed like it recently, but corn planting time will soon be upon us. Late winter/early spring always is a good time to do inspection, maintenance and adjustment of planting equipment, whether you are using the same planter you parked in the shed last spring, a “new to you” planter or even a brand new planter straight from the factory.

The main results of poor planter maintenance are poor seed spacing and non-uniform emergence. Uneven plant spacing can cause corn yield loss of 2.5 bushels per acre for each inch of deviation from the proper spacing. Deviations can be the result of plants being too close because an extra seed is dropped, or too far as the result of skips, or a seed that doesn’t germinate.

You are not going to get 100 percent accuracy, but the ideal goal to shoot for is to have no greater than a 2-inch standard deviation in plant spacing. If you are within that, you are doing fairly well, but a deviation of 3 to 5 inches or more can result in a seven to 10 bushel-per-acre yield loss, which is unacceptable. If plant spacing and emergence are both a problem, then yield losses could be substantial. Lost yield translates to lost revenue when the crop is marketed.

So what should you be doing to ensure accurate planting this spring? Our neighbors to the north at Penn State University Extension share the following tips on planter maintenance.

Meters. Metering units have to work well or you’ll get frequent skips, doubles and triples. To guarantee optimal performance, take metering units apart every winter. Remove dirt and clean the hood with soapy water. Replace cracked plastic covers. Replace broken fingers in a finger-pickup meter. Seed brushes need to be replaced when worn.

If a groove has formed in the chromium house of the metering unit, it is time to replace it. The belt – in finger pick-up meters – should be flexible, not have cracks in it and should be clean. Clean with soapy water and let it dry before putting it back in. If you have a vacuum or air meter, check for leaks and appropriate vacuum or air pressure.

Planter unit. Accurate depth placement can be compromised if planter units are loose or wobbly. You should not be able to easily lift up your unit or move it sideways. Look across your planter units from the side. Are they all at the same height? If one unit is either up or down compared to the others, it needs work. A common problem is that some bolts are loose or additional bushings are needed.

Seed opener disks. Seed opener disks need to have a minimum diameter (check operator manual) or they will not place the seed at the appropriate depth. Seed opener disks also need to come together in the front – they should usually touch for 3 inches, but this might vary depending on planter. Stick two business cards between the openers and move them as close together as possible. If opener disks are worn too much, you will get a “W” shaped seed slot instead of the desired “V” slot.

Seed tubes. The end of seed tubes may wear to the extent that they curl inward, catching seeds. There often is a hook halfway up that easily can break off. Seed tube guards need to have their minimum width and be fastened correctly or damage to the seed tube is likely.

Seed firmers. These help to press the seed down in the furrow, guaranteeing more accurate depth placement of the seeds. The tension can be adjusted with a bolt. If the seed firmers are worn too much, they need to be replaced.

Depth wheels. Depth wheels should run tight against disks. Change washers from inside to outside (or vice versa) of depth wheel, if necessary. If this doesn’t resolve the problem, the depth wheel arm needs to be replaced.

Coulters. Check the diameter of the coulters and replace them, if needed. You should adjust the depth of worn coulters that still are usable.

Closing wheels. Closing wheels need to have an intact spring, and need to be checked for damage or wear. Bearings cannot be wobbly or too tight. The bottoms of rubber or cast iron closing wheels need to be 1.5 to 2 inches apart. The closing wheel arm cannot have too much play or bushings or the entire arm may need replaced.

Alignment of coulters, opener disks and closing wheels. Take a rope and pull it straight from the front coulter to the closing wheels. The firming wheels, seed openers and coulters should all be in line. Closing wheels should not run on top of the seed furrow.

Chains and sprockets. Check all chains and their sprockets. If they are worn too much, they need to be replaced. They need to have the appropriate tension and should be regularly greased.

Matt Adams is a Hardin County Extension agent for agriculture and natural resources.