Corn planting populations. It’s a balancing act. The secret is knowing which factors impact corn populations - including seed variety, seed quality, weather and soil conditions — and how to accommodate for those factors in your operation.
However, even though striving for maximum yield is typically top of mind, you need to aim for the optimal economic yield by factoring in the cost of additional seed, which could potentially outweigh yield gain profits from higher planting densities.
There’s a lot to take into account, and if you need a hand determining how and when to adjust your corn planting populations, we are here to help.
How to calculate corn planting population
You should make your corn population decisions based on the field’s three- to five-year history, and you may want to skip exceptionally low- or high-yield years in your calculation to get the best average.¹
To find the optimum economical yield, you need to compare the cost of additional seed to see if it outweighs the potential yield gain. For example, the average seed corn cost per bag is $267², and a bag contains approximately 80,000 kernels, enough to plant around 2.2 acres (at the recommended corn planting population of 35,000 per acre). Planting at a higher rate may produce higher yield, but that yield may not be high enough to justify the cost of the additional seed.
Below, you will find an overview of the primary factors to consider when calculating corn population.
Corn seed varieties
Pay attention to traits such as stalk quality when adjusting corn planting populations. Due to different genetic backgrounds, certain hybrids may be better suited for higher planting densities than others.
In high plant populations, competition for light in the crop canopy causes corn plants to grow tall and thin, significantly reducing stalk strength and leading to increased risk of lodging and standability problems.
If using the same hybrid as in past seasons, evaluate how that hybrid performed and if corn populations should be adjusted by looking for telltale signs like tip back. If kernels have formed to the tip of the ear with no “tip-back”, you likely could have increased the corn seeding rate. On the other hand, if more than 5% of the plants are barren, or if most ears have fewer than 250 kernels per ear, the corn seeding rate was likely too high.
It is also recommended to monitor nutrient status, as severe nitrogen (N) deficiency significantly reduces final number of grains, ear size and ear number.³
Seed quality
Investing in high-quality seed has many benefits, and in regard to corn population, seed germination percentage is a key factor in deciding optimal corn seeding rate.
If seed germination rates fall below 90%, you should increase corn populations to compensate for seeds that fail to germinate.⁴
Soil condition
Highly productive soils are generally able to sustain higher populations. To support higher plant populations while providing the highest yield potential, soils must have both adequate drainage and plant-available water.
Additionally, don’t underestimate how corn seedbed preparation can aid soil productivity, resulting in higher yield potential.
Harsh environments or poor weather conditions
Recommended corn planting populations are partially based on typical conditions for the specific region you’re growing in, such as a dryland or irrigated environment.
Additionally, environmental conditions are factored in. For example, planting into cooler or wetter conditions is not ideal and puts seed at higher risk for seedling pathogen infection. If your planting conditions are poor, increasing the corn seeding rate is recommended.
It is important to note that seed tag germination rates are based on a warm germination test, meaning the germination test was conducted in an ideal environment at 77 F. If you want to gauge how your seed will germinate in more realistic, poor spring conditions, cold germination tests are better indicators of how hybrids will perform since seeds are tested in a cold, damp environment replicating early-season soil. Contact your local seed lab to look into cold germination tests.
Experts are available to help you make your decisions. Reach out to your seed retailer, a nearby extension office agent, or a seed company professional like your regional BASF representative.
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Endnotes
- “Plant Populations and Seeding Rates.” Agronomic Crops Network, Ohio State University Extension, agcrops.osu.edu/node/4421. Accessed 7 Nov. 2024.
- Jiao, Hongxia. “Seed Corn Costs: Cost of Seed Company Financing Vs. Traditional Financing.” Farmdoc Daily, 6 Feb. 2020, farmdocdaily.illinois.edu/2019/10/seed-corn-costs-cost-of-seed-company-financing-vs-traditional-financing.html. Accessed 7 Nov. 2024.
- Ciampitti, Ignacio, and Adrian Correndo. “Agronomy EUpdate Issue 898.” 24 Mar. 2022, eupdate.agronomy.ksu.edu/article/optimal-corn-seeding-rate-recommendations-486-2. Accessed 7 Nov. 2024.
- Licht, Mark, and Zachary Clemens. “Considerations for Corn Seeding Rates.” Integrated Crop Management, 9 Apr. 2021, crops.extension.iastate.edu/blog/mark-licht-zachary-clemens/considerations-corn-seeding-rates. Accessed 7 Nov. 2024.
