Farmers May Add Corn Plants Instead Of Acres

Farmer interest in pushing corn populations higher is even stronger than usual this spring, with corn prices in the $6 to $7 per bushel range. How high of a plant population should you aim for on your fields?

Published on: Feb 26, 2011

Corn plant populations continue to be a topic of interest to farmers. It was an issue two years ago in a Wallaces Farmer article titled, "Right Population to Plant Remains a Mystery," and still remains a big issue in the industry today.

Farmer interest in pushing populations higher is even stronger this spring, as market prices have risen to the $6 to $7 per bushel range. You can grow more corn by planting more acres of the crop, or you can try to grow more corn on the same number of acres by increasing plant population to boost yield per acre.

Commodity market analysts say corn needs to take 5 million to 6 million acres away from soybeans this spring in the U.S., to get enough corn acres planted to help meet anticipated market demand for corn in the coming year. However, that much of an increase in corn acreage isn't likely to happen in 2011 because prices are also high for crops such as soybeans, wheat and cotton which are competing with corn for acreage.

With competition for acres, corn populations will likely increase

If farmers need to plant at least 5 million to 6 million more acres than the 88.2 million acres of corn they planted last year nationwide, that means 93 million to 94 million acres will need to be planted this spring. Most early planting estimates are projecting 2011 corn planting at 91 million to 92 million acres nationwide.

One way farmers will try to produce more corn is to boost plant populations, says Bill Horan, who farms near Rockwell City in western Iowa.  Five years ago he averaged 28,000 corn plants per acre, and this year he'll aim for around 34,000 plants per acre as an established stand. "With corn at $3 per bushel, you aren't likely to buy the extra seed and plant a higher population per acre," he observes. "At $6 or $7 corn, you will."

How high to push plant populations depends on several factors

How high can you push corn plant populations in your fields? It depends on several key considerations, says Nick Benson, corn product specialist at Latham Hi-Tech Seeds. He provides the following guidelines for farmers to keep in mind when making their corn seeding rate decisions this spring.

One thing to remember, of course, is the difference between seeds per acre and plants per acre. Generally, you need to plant 5% to 10% more seeds per acre than the plant population you are aiming for as an established stand—to account for normal plant mortality.

What the data says. In the past two years, more research has been conducted on plant populations than in all previous years combined, says Benson. "What we have to remember is these studies were done on good soils and they measure strictly yields. All we're seeing in these comparisons are yield results—there has never been a study that compares stalk lodging in relation to yield or population increases. These skewed results may encourage some growers to plant high populations that carry a bigger risk than they do reward."

Pushing plant populations too high. Planting corn populations that are too high for your particular soil type and field conditions can result in diminishing returns. "Data tells us if you're planting over 35,000 to 36,000 plants per acre, then you're possibly looking at the law of diminishing returns," says Benson.

"But what we need to consider is that if you push your population too high, you're at significant risk of inter root competition or root crowding," he adds. "You can end up with stunted root growth, leaf shadowing, less photosynthesis and less grain fill. We used to think the answer was a hybrid with a higher leaf angle that could grow in tighter quarters, but this doesn't always equate to a hybrid that will excel in higher population situations."

Recommendations for your conditions. Recommendations for plant populations should be based on each grower's particular soil types and field conditions. Work with your seed consultant.

Every grower experiences different conditions compared to neighbors, and every field contains different conditions than the next. Benson has a grower who can plant 36,000 on his rich peat ground with a population positive plant that can handle it, but that same grower can cross fields and enter different conditions that require a much different population.

Someone with soils that have a high Corn Suitability Rating and who makes multiple nitrogen applications, and who sprays fungicide and sprays perfectly may be able to plant and achieve an established stand as high as 42,000 or even 45,000 plants per acre, but you have to base these decisions on what's best for your particular soil. Because of these varying conditions, it's important for growers to work with their seed consultant to ensure they're placing the right seed at the right population for their soil.

Change it up. Benson says the first thing growers can do to help increase plant population is to get out of the planter and change the population. Growers may have more productive soils that can handle heavier populations in one portion of their field, and then very light soils in other parts of the field that can't handle higher populations. Population should be changed accordingly.

For more information, you can contact Benson at or call 319-415-2312 or visit the website