by Deborah Jeanne Sergeant

Increasing yields should always be a priority to any corn grower. At Cornell’s virtual Corn Congress, Connor Sible of the Department of Crop Sciences at the University of Illinois presented “Understanding Biologicals for Improved Corn Management” to share his findings.

“Regardless of where you are in ag, biologicals are really exploding in the market,” Sible said, “and with all the claims in the world. You need to decide: Do you need that product? Is it the right fit for your system? And what is the goal on your farm?”

It all starts with base management. The world record corn yield is 616 bushels/acre, set in 2019; the U.S. record, set in 2017, is only 177 bushels. That means there’s a lot of room for improvement, according to Sible. “It comes down to how we manage crops.”

Standard management includes the selection of solid genetics. High yielding varieties will produce more corn. Achieving optimal plant populations means more corn per acre. That starts with plant spacing.

The population per acre has steadily increased since the 1960s with a directly corresponding increase in yield. But if plants are too close, the root systems become smaller, more shallow and less stable. Sible and his team have found that at 30,000 plants/acre, the root ball looks large and healthy. At 36,000, it is noticeably smaller.

“What we find is that for every 1,000 increase in population, you have 2.5% decrease in root mass,” Sible said. “These smaller root systems are more susceptible to stress and pests. We have to protect the roots with biological controls to help minimize stress.”

Ensuring adequate nutrient availability also helps improve yield. For corn, that means the optimal amount of nitrogen and phosphorus at the right time.

Sible summed up the five tenets of crop management – genetics, plant population, nutrients, weed control and disease control – and said, “If you don’t do these five things, you will fall short.”

Once the foundation of good management has been established, biologicals are the next step. “I see a lot of potential, and having studied it for five years, I have seen dramatic improvements,” Sible said. “These are something to be excited about in the next five to 10 years. There’s lots of versatility if you have the right product.” Biologicals can be used with seed treatments (though it’s not recommended), in-furrow (with starter fertilizer), via foliar application at vegetative stages (with post herbicide), at foliar reproductive stages (with fungicides and insecticides), on dry fertilizers and on crop residues.

Sible noted three categories of biologicals: plant growth regulators (hormones), beneficial microbes (the living) and biostimulants (the dead). “Nematodes are beneficial microbes,” he offered as an example.

Much of the work in biologicals began with using legumes to increase nitrogen availability for heavy nitrogen users like corn. Sible said nitrogen-fixing bacteria can increase plant-available nitrogen, allowing producers to cut back the amount that they apply to their corn.

His 2020 study on the influence of nitrogen rate and PROVEN treatment on grain yield with soil with a 2.5% to 6% organic matter showed an average of three more bushels per acre. Envita increased yield by 11 bushels.

Using natural bacteria Azospirillum even on fields untreated by nitrogen added seven more bushels. With 80 pounds of nitrogen plus Azospirillum, yield rose by three bushels, and with 160 pounds of nitrogen, yield increased by 12 bushels.

“When we added the in-furrow nitrogen fixer, we got our greatest responses to these,” Sible said.

Bacteria can also increase the availability of phosphorus. “There’s a lot of phosphorus in our soils, but it’s not all plant available,” Sible said.

He researched iNvitorage, one brand of treatment, and found an increase of eight bushels when used in furrow, along the plant roots. The treatment includes two bacteria: one to fix nitrogen and one to solubilize phosphorus. In addition to increased yield, “we did get improved phosphorus and zinc uptake into the crop,” he said.

By using these biological inputs, farmers may be able to reduce phosphorus application to an extent, perhaps from 60 pounds to 50 pounds per acre.

Sible said using mycorrhizal fungi may help extend the root system of corn. “They make a bigger root system by growing and exploring the soil and making better access to soil nutrition and moisture,” he said.

Getting fertilizer in the rows complements this effect. “Hyphae explore the soil system,” Sible said. “Practices like in-season coulter side-dress or manual weed cultivation may disrupt the fungal network, reducing efficacy.”

Enzymes are the newest type of biological coming to market, Sible said. They increase the availability of organic phosphorus. While organic matter in the soil may contain phosphorus, plants cannot use it. That’s where enzymes called phosphatases come in, breaking it apart and creating greater availability of organic phosphorus.

The soil environment can determine what enzymes would be helpful. Humic/fulvic acids chelate soil cations and feed microbes.

“If you chelate the zinc, it keeps phosphorus available,” Sible said. “People ask how long these last in the soils. They’re pretty resistant and can be active for a good portion of time before the microbes tear them apart.”

He said humic/fulvic acids are available in a variety of forms and the desired placement of the product determines which should be used.

Sugar can also affect corn yield, as it supplies energy for soil microbes. “Sugar plus starter is synergistic,” Sible said. “Supply enough for microbes and plants and we see a happy balance.”

In trials from 2019 and 2020, researchers found a three-bushel increase in corn treated with starter fertilizer and an in-furrow treatment of high fructose corn syrup.

The biological market is vast and full of a variety of product options for growers. While certain biologicals are similar in type, each product is unique. Sible encouraged producers to understand any biological input they are considering for their cornfields and how they would perform with their farm’s environment and management system.

“Maybe try five acres this year, 10 acres next year,” Sible suggested.