Setting the table for high population

Much like housing and feeding guests at a crowded holiday gathering, providing enough space and nutrients for a jam-packed cornfield to achieve top yields requires planning, attentiveness and more than a little flexibility. That is particularly true for farmers pushing for maximum yields by planting narrow rows with higher plant populations.

Setting the table for high population

Much like housing and feeding guests at a crowded holiday gathering, providing enough space and nutrients for a jam-packed cornfield to achieve top yields requires planning, attentiveness and more than a little flexibility. That is particularly true for farmers pushing for maximum yields by planting narrow rows with higher plant populations.

Ron Thomas and son Jeff of Unionville in southern Iowa made the switch to narrower row spacing a decade ago. The father-and-son farming duo converted to narrow rows as a way to increase their productivity.

“In 2005 we changed from 30-inch rows to 20-inch row spacing because the narrower rows allow for better nutrient use by the corn and better use of sunlight, which helps result in up to a 20% yield increase,” Ron Thomas says. Their southern Iowa farm includes highly productive soil in a bottomland area near a creek, but it also includes sloping ground that isn’t as productive. Still, they’re disappointed if they average less than 200 bushels per acre. The Thomases believe the combination of their in-depth nitrogen plan and 20-inch corn rows makes their 200-bushel goal achievable.

Key Points

• Nutrient management is key to high-population corn.

• Nitrogen availability, timing favor sidedress application.

• With more plants per acre, variety selection is important.

Population explosion

In 2014, they planted most of their cornfields at populations of 37,000 to 38,000 seeds per acre, though in some areas they went as high as 40,000. Last year was wet during planting, followed by 1½ months of dry weather. They believe with better weather conditions, these higher populations will provide an even greater yield.

Plant populations have been on the increase in many fields throughout the Corn Belt the past few years, as both public and private research shows one feasible way to increase per-acre yield is by increasing the number of plants on that acre.

In most cases, this requires farmers to narrow their row spacing, which in turn increases the amount of seed needed. Those crowded quarters can present some challenges, particularly when it comes to providing the necessary nutrients.

“With the higher populations, the grower is investing more in his seed cost,” says Tim Book, technical sales manager for Verdesian Life Sciences, covering parts of Iowa, Missouri and Kansas. “Each one of those plants needs to be optimized to produce as many kernels and be as heavy as possible. It’s about efficiency and using that space in the soil to produce grain.”

The Thomases apply nitrogen two to three times a year, depending on the growing season. This, along with use of a nitrogen stabilizer, ensures availability of these fertilizer nutrients when plants need them most.

“We usually fall-apply anhydrous and then add 32% liquid N mixed with our chemicals, followed by flying on some dry nitrogen fertilizer in mid- to late June,” says Thomas.

Because the plants can’t get enough nutrients for the full season from fall or preplant anhydrous applications, sidedressing nitrogen is a must to reach maximum yields. The increased plant population density makes in-season fertilizer applications more difficult.

“With the narrow rows, it’s hard to apply anything without damaging crops once they are out of the ground,” Thomas adds. “Applicators find it difficult to stay between the rows so we have them cross the row, which causes less damage.”

Sidedressing favored

Nitrogen availability and timing favors sidedress applications. A recently completed three-year study found that corn yields were significantly higher with narrow rows and sidedress nitrogen applications than with any other row width or timing combination.

The North Carolina State study showed a 19% grain yield increase in response to applications of nitrogen fertilizer. A key to the success was availability of nitrogen, which means the use of split applications.

It also means many farmers planting high populations rely on nitrogen stabilizers such as NutriSphere-N Nitrogen Fertilizer Manager to enhance the nitrogen availability throughout the growing season. The Thomases add Nutrisphere-N to their liquid fertilizer because it helps reduce nitrogen loss when it’s applied and it makes the nutrient more available when crops need it. “We definitely see a yield increase with its use as it keeps nitrogen from volatilizing when applied,” Thomas says.

NutriSphere-N helps farmers reduce nitrogen loss from volatilization, leaching and denitrification, and can work with any nutrient management program. “For growers who are attempting to maximize that acre of production to get top end yields, the soil can’t hold enough nitrogen in one application,” adds Book. “Stabilizers reduce the loss that can occur from volatilization, denitrification and leaching.”

Variety selection

Nutrients are key to reaching yield potential, but so too is picking the right seed, as not all corn hybrids are bred for success in this type of environment. Stalk lodging can be an issue for plants grown in such close quarters, plus the additional crop residue also requires management.

“Due to competition between plants, corn planted in 20-inch rows will grow up to 2 feet taller than the same hybrid in 30-inch rows,” says Thomas. Because of that, he focuses on choosing and planting shorter hybrids without compromising yield potential. “We still fertilize for the same yield goals as we did at 30- inch rows, but they yield better.”

Seed companies are taking notice of the growing trend toward narrower rows and higher plant populations. Many now offer shorter-stature varieties bred specifically for this type of production.

After planting corn in narrow rows for more than 10 years, the Thomases say they have no immediate plans to change. When things are working, there’s no reason to switch. But there’s always room to try something new in field trials on your farm.

“We will stay with 20-inch row corn with most of our populations at 37,000 to 38,000 seeds per acre,” Thomas says, adding, “On some of our better land we may push populations to 40,000 to 42,000 to experiment.”

Source: Verdesian Life Sciences

This article published in the February, 2015 edition of WALLACES FARMER.

All rights reserved. Copyright Farm Progress Cos. 2015.

Plant Population

Narrow-Row Planting

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