The following are some tips and ideas on how to avoid key corn planting mistakes. If you have other thoughts you would like to add to the discussion, please e-mail me at greg.stewart@maizex.com.

Missed the First Planting Window. This is a result of not having the planter prepared for an early planting window. Here are some key reasons why growers miss that first good planting window: new tractor or new planter not talking to each other, (see Table 1), planter has a crimped cable or hydraulic hose that didn’t get noticed, seed and fertilizer not secured or organized into a field plan. Solutions: Start early to get the planter ready to go and ensure your whole team has a copy of the planting plan!

  • Make sure the firmware on the GPS receiver and in-cab display are up-to-date.
  • Make sure GPS receiver offsets and planter offsets are correctly input into the display for accurate ON/OFF actuation of auto-row control and that seeding rates change in the correct location for variable-rate seeding.
  • Back-up and archive past years planting data in a secure location on a farm computer, external hard drive, cloud site, or similar.
  • If purchasing a differential correction, make sure your subscription is up-to-date before the planting season.
  • Look over wiring harnesses and connectors for damage and loose connections.

5-point technology checklist from John Fulton, The Ohio State University:
Pre-season planter tips – Ohio Ag Net | Ohio's Country Journal (ocj.com)

Late Emerging Seeds. It has become clear over the years that one of the single biggest yield robbers is seeds that emerge later than the seeds around them. In some cases, especially under warm conditions, as little as a 12-hour delay may cause significant yield reductions in that late emerging plant. Causes for this delay are often moisture related as the seed struggles to obtain adequate moisture to immediately start the germination process. Solutions: Be sure double disc openers are making a smooth V trench (check disc diameter and contact point), ensure seed tubes are free of cracks or bumps and depth gauge wheels are adjusted snuggly against double discs. If you start planting corn on April 25 at a depth of 1.75” you should consider moving the depth downwards as the season progresses and as soil conditions become drier and warmer. A ¼” adjustment each week ensures a planting depth on May 25 of 2.75” and significantly reduces the chances of late emerging plants. See Table 2 for the three-year depth summary.

Table 2. Three-year results from planting depth trials conducted by Maizex Seeds.
YEAR 2018 2019 2020
Planting Depth 2'' 3'' 2'' 3'' 2'' 3''
# of sites              11                   27                   21
Yield (bu/ac) 207 208 204 208 212 210
Population (plants per acre) na na 31,173 32,109 30,181 30,752
Wins (<3 bu/acre) 27% 36% 7% 44% 33% 24%

In addition, remember to get off the tractor and check seed depth regularly including when pulling into a new field.Often, you might be planting shallower than you think. Carry a seed depth finder to measure depth and bring another one or a straight piece of wood to put on the horizontal at firm ground level. This ensures you are measuring true seeding depth.

Seeds Encased. When soil moistures are high it can be difficult to make the seed trench, place the seed, and push the trench closed and not create conditions where the hardening of the seed trench may become a barrier to early shoot growth and root proliferation. Solutions: Check the weather forecast and try to convince yourself that waiting 18 hours before entering the field may be a better plan than pushing ahead with planting intentions under damp conditions. Adjust the row unit down pressure so that the gauge wheels are not excessively pressed into the soil. With the planter in the field and in planting position, the row unit contact pressure should not prevent you from turning the depth gauge wheels by hand (with a reasonable effort). Consider switching to closing wheels that have cogs or spikes to allow for crumbling or stitching the trench closed rather than simply squeezing it back together.

Figure 1. Closing wheel selection can be quite subjective; growers will need to get a feel for what works best for them. In many cases the crumbling closing wheels only provide a significant advantage when conditions are more challenging (i.e., damp conditions, heavier soils, more residue, etc.). In my experience something like those pictured to the right do a nice job across a range of conditions.

Seed Missing. A missing seed or skip is much more of a yield reducer than a misplaced seed (i.e. 4” of space rather than 6” of space), more of a risk to yield than even a true double, and often more of a risk than a late emerger, especially if the late emerger is only one leaf stage behind its neighbours. Of course, this yield reduction is driven by a reduced ear count; two skips in 17’5” could mean an ear count of 29,000 rather than 31,000 and on high productivity ground that could mean a yield hit of 6 -12 bu/acre. Solutions: Check meters for seeding accuracy, ensure seed drop counts line up with what your monitor is claiming. A short length of chain with two S-hooks can allow you to raise up the closing wheels and permit an accurate job of counting seed in the open trench or on a driveway (see Figure 2).

Figure 2.A short piece of chain with S-hooks on the ends can lift the tail stock out of the way and make seed counting and seed trench evaluation much easier.

Seed Interference. Some seeds fail to meet their potential because they get exposed to residue pinned in the seed trench or the seed trench does not get closed properly. In these cases, there is often enough moisture to allow for germination, but then the interference from residue or air gaps stress the seedling as it emerges and although it may emerge on time it quickly falls behind. Solutions: Floating row cleaners that skim the soil surface can reduce hair pinning of residue. Having row cleaners that allow you to adjust their aggressiveness from the cab is a game changer! Be sure row unit tail stocks and the closing wheels are centered over the row. If you are struggling to close the trench perfectly because of a rough seedbed, consider planting a bit deeper.

Seeds Starved. Inadequate nitrogen supply in the row zone can stall an otherwise great start to a corn crop. Research suggests that soil nitrate levels in the row zone need to be at least 40 PPM. In 2021 Maizex plot work demonstrated that the fields most likely to not make this threshold had only liquid fertilizer, in-furrow, on the planter (i.e., 3 lbs N/acre) and broadcast rates of about 30-40 lbs of N at planting time, with the remainder of the N being applied after the 6-leaf corn stage. Solution: Realizing that it is often not convenient to run more N through the planter the solution is to increase the broadcast N rate either before or just after planting to at least 60 lbs N/acre.

Final Thoughts

A measurement of your planting success can be defined by ECC (Ear Count Conversion). This is simply the percentage of seeds dropped that produce a harvestable ear come fall. At Maizex, when we monitor a field, we gather three numbers:

1) Seed Drop

2) Plant Stand in mid-June and,

3) Ear Count at Yield Tour time (end of August).

For example, a field has an average seed drop of 33,800; this results in a plant stand in June of 32,800 and a final ear count of 30,750. The Ear Count Conversion for this field is 30,750/33,800 = 91%. In this field it appears the ECC could be better, (94% is a good goal) and it appears that the problem was not in total emergence but in too many of those emerged plants not developing a solid ear. This perhaps points to late emergers or sidewall compaction causing the plants to underperform after they emerge.

You can watch some videos on planter set-up that will review the above ideas plus many more. They can be found at:

Power Planter Preparation

Maizex Moving: Planter Preparation

If you have any questions about corn plant stand evaluation or would like some assistance in evaluating your fields or planter performance, please reach out to us at Maizex!