Corn and Soybean Planter Tune-up for Improved Seed Emergence

By Joseph Akins and Delbert G. Voight 

It's almost time for planters to enter the field again and begin the process of providing feed and forage for farms across the commonwealth. The planting operation is one of the most critical steps in achieving high crop yield and quality. The purpose of the planter or drill is to open a furrow to place the seed at the same depth so that each seed will emerge evenly and create a tabletop stand in the field. The effect of uneven emergence on corn yields has been well documented, and most research shows that when corn plants emerge late relative to neighboring plants, the yields of the late emerged plants are reduced. Research in Oklahoma showed that when 30% of plants were delayed 2 and 5 days, yields were reduced by between 3-14% and 10-25%, respectively (1). Another study conducted in 2015-2016 by Virginia Cooperative Extension performed a similar analysis across multiple sites in the state looking at yields per acre of plants that showed delayed emergence (2, 3). They found that plants that emerged just one day late had yields that were 3% to 26% lower per plant. Yields of plants that emerged two days after the first emergers were 2% to 44% lower per plant. If these per plant yields represented 15% of a corn stand, that would translate to a yield loss of up to 6% across the entire stand if plants emerged 2 days late. To avoid these issues, follow the steps below to ensure that your planter is 100% ready to go this spring.

Worn seed disc, new discs are 15". These openers could not maintain the required 3" of contact with each other.

Tips for equipment maintenance

1. The initial opener (wavy/fluted coulter) cuts open the residue to allow the disc opener to work its magic. The front coulter bears the brunt of the wear and should be checked and replaced more often. Be sure the coulters do not cut deeper than the disc openers.
2. Many poor plant stands are a result of issues with the disc openers. The disc openers can be easily checked and replaced by the operator. The disc opener serves to lay a V-shaped trench that receives the seed and sets it at the bottom of the V. If the discs are worn, the trench turns into a W and the seed is placed at varying positions, resulting in uneven emergence. Simply taking two business cards and positioning them from the top and bottom of the disc openers should reveal that they stop about 3 inches from each other. At the very least, the card should not be easily slipped between them. In some cases, some shims placed on the shaft will help move the discs together. In other cases, total replacement may be necessary. Take the time now to replace them and not when the soil temperature is 50°.
3. The closing wheels can make or break the planting process. On loose ground, closing wheels with too much pressure can kick the seed up in the V slot and ruin the disc openers' intended purpose. The goal of the closing wheel is to close the V slot and firm the soil around the seed. On hard-packed soil, the closing wheels will need more pressure (maybe even cast closing wheels) to ensure seed coverage and firming. When downward pressure is insufficient, the V slot may be left nearly wide open which will negatively impact emergence. The closing wheels should be in the centerline of the disc openers. To check that the closing wheels are centered, simply place a ruler between the discs wedged on the center line and then again between the closing wheels.
4. Check for in-line flow from front to back and side to side. Normally I find the outer row units to be bent (quite severely in some cases) due to the turning action of the planter when the units might not have been completely out of the soil. Yes, I am guilty of this as well! Sure, most of you will say I don’t have that problem, but have you checked lately?
5. While you are there, check the gauge wheels that control the planting depth. Especially in no-till or when rolling, the gauge wheels need to be set appropriately to get the seed to the proper depth. Gauge wheel settings will be influenced by the amount of residue on the soil surface. In high residue situations, setting the gauge wheels too shallow can result in uneven growth. Gauge wheels should touch the double-disc openers when a load is on the planter unit in the field. If gauge wheels are too far away from the disc blades, soil will get into the seed trench before the seed gets there! Again, shims can be used to take up the space.
6. Most common planters have a seed hopper that holds the seed and drops it through a tube down to the disc openers. Additionally, many planters have an eye sensor that sees the seed and transmits a signal to a unit to let the operator know the seed is moving through the tube. The tube and eye should be cleaned when needed (e.g., when mice nests somehow get into the tubes).
7. The seed metering device should be cleaned as well. Air and vacuum metering devices should be disassembled and cleaned, and all air supply tubes and seals checked for leaks or cracks. On finger pick up units, the brush (have not replaced in two years then replace now) and back plate should be viewed and worn parts replaced. Many dealer locations offer a service to check the metering devices for proper function for a modest fee. I highly recommend this service. If not done last fall, now is a good time to get that accomplished. All normal grease and lubricants should be used on chains and key pivot points.
8. Each planter unit should be lifted to determine if the bushings need to be tightened or replaced. If more than ¾ inch of play is noted when the unit is lifted, the bushing should be replaced. While the planter is lifted (be sure stops are in place for safety), check to see if all units are level with each other from side to side.
9. Many planters come with fertilizer or insecticide delivery systems. These too will need attention. Fertilizer injury often results from the application of material too close to the seed. Check to see that a 2 by 2 placement of the material is achieved by using a set of straight sticks centered on the seed trench and another centered on the fertilizer tube. If liquid, be sure the nozzle is directed to the proper location. Dry insecticide boxes should also be cleaned of mouse nests and the metering device checked for wear. It is critical to be sure that the T band or in furrow tube is properly placed and clear of any obstructions.
10. One final note on leveling: The bottom of the tongue should be leveled with a bubble level. To achieve a level planter, the drawbar can be raised or lowered as needed. By ensuring that all the planter components are operating properly, we can better utilize the few days of ideal planting conditions this spring and spend them in the field and not in the shop.

Valuable video resources for checking your planter

• Planter leveling, row cleaners, and coulters
• Opening disks and gauge wheels
• Closing wheels