Update from the Field: Popular Population
Posted by Dave Dyson, Agronomist on April 23, 2019
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As the ground warms in mid-April everyone is preparing their planters for the upcoming compressed spring planting season and wondering, “At what population should I drop my corn seed this year?” Corn populations have not always pushed 32,000 plants per acre. In fact, 40 years ago the average corn plant population ranged between 19,000 to 22,000 plants/acre. Over the past 40 years, the average corn seeding rates used by corn growers in North America have been steadily increasing by about 275 seeds/acre per year, while U.S. average yields have increased by about 2 bu/acre per year.
Every year the USDA-NASS counts final stands in the fall and reports the results. In 2018, Illinois came in with the highest plant density of 32,000 plants/acre, followed by Iowa at 31,100, Minnesota at 30,900, and Indiana at 30,400. The seeding rates have moved higher, and with the additional decrease in row width from 36 inches to 30 inches, the plant density has gone up too. The optimal plant density range has shifted higher as well (figure 1). Today’s hybrids can withstand plant density rates in the mid 30,000 plants/acre.
Figure 1: This graph from Pioneer Hybrids shows the shift in optimal plant density over time.
There is a point of diminishing returns, however. Bob Nielsen, Professor of Agronomy from Purdue University, has a theory that growers may be limited by the amount of sunlight getting to the individual plant. Pioneer Hybrids has found that even under ideal conditions, increasing yield response stops somewhere around 40,000 plants/acre. When planting on non-irrigated ground, corn populations should stop between 33,000 to 35,000 plants/acre. On drought-susceptible soils, producers should be looking to cap corn plant populations at 28,000 plants/acre.
The addition of potassium can prevent seedling death due to nutrient deficiency, thereby increasing yield at harvest. The application of Korrect™ (3-0-20) has proven to supply a safe and readily available supply of potassium directly to the plant when placed in-furrow. In a research trial conducted in 2018 in Indiana, the addition of Korrect in-furrow yielded a 15.71 bu/ac advantage compared to the check (figure 2).
Figure 2: In a study conducted in Walton, Indiana in 2018, Korrect was applied in-furrow with Season Pass with AVAIL. The treatment observed a 15.71bu/ac increase compared to the check.
In conclusion, I recommend growers proceed with caution, as you should not start increasing or decreasing seeding rates without a plan. If you want to begin adjusting your plant population, plant your field with a target plant density based upon agronomic advice. Then for one round in a few parts of the field, increase the plant density by 10%. This will prove that either you need to increase the plant density or not. Seedling death can be decreased by supplying young plants with an ample amount of nutrients that are both close to the seed and readily available. Contact an Ag Advisor from The Andersons for nutrient and seed population recommendations.
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Dave Dyson is a regional agronomist for The Andersons’ Farm Centers which are located throughout Ohio, Michigan, and Indiana. He is an Indiana native and grew up on a dairy farm in Miami County. A graduate of Purdue University with a degree in Crop & Soil Science, Dave has a deep knowledge of various agronomic topics and is committed to helping growers improve their crops. If you have any questions, Dave can be reached at david_dyson@andersonsinc.com.
© 2019 The Andersons, Inc. All rights reserved. GoldStart, and Season Pass are registered trademarks of The Andersons, Inc. Korrect is a trademark of The Andersons, Inc. AVAIL is a registered trademark of Verdesian Life Sciences.
