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5 microbes your soil needs for success5 microbes your soil needs for success

A look at soil microbes that help root growth and relieve plant stress.

Mindy Ward

April 25, 2019

6 Slides

Farmers are planting cover crops, applying manure or using no-till practices in their fields to improve soil health. While these strategies work in part, they may be missing one important aspect to these soil management practices: microbes.

“The whole point is to feed the microbes,” says Dave Stark, president of Holganix Agriculture. Holganix is a manufacturer of organic microbial inoculants for fertilizer. A known player in the turf and landscape industry, Holganix expanded to the agriculture space four years ago.

“It is the microbes that makes the soil work,” Stark adds, “but many do not know much about microbes.”

What are microbes?

There are five different types of soil microbes: bacteria, fungi, actinomycetes, protozoa and nematodes. Each of these microbe types has a different role in boosting soil and plant health.

Bacteria. Bacteria are the smallest microbes. “They are the workhorses,” Stark says. In a healthy soil situation, a bacterium can divide every 20 minutes. “They are the most abundant and biologically diverse,” Stark adds. They live within a half-inch of the root system. Bacteria absorb the nutrients in the fertilizer, especially nitrates.

Fungi. Fungi live at the plant root. It is the white, featherlike material seen on a plant root. Stark says this type of beneficial fungi is tiny — smaller than a root hair — and can get between soil particles. “They essentially can make the plant root 1,000 times larger than the roots themselves,” he says. Fungi help with water and nutrient uptake. Fungi also eat bacteria and are useful in solubilizing nutrients such as phosphorus, which may be abundant in soils but are not in a chemical form the plant can use.

Actinomycetes. Actinomycetes once were classified as fungi and act similarly in the soil. However, some actinomycetes are predators and will harm the plant while others living in the soil can act as antibiotics for the plant.

Protozoa. Protozoa eat bacteria. Stark says since bacteria absorb fertilizer, when the protozoa eat the bacteria, they release nutrients back into the soil. When protozoa are missing from the soil, farmers may experience yellow corn after nitrogen application. “Sometimes there is too much bacteria and not enough competitors like protozoa,” Stark says. “There needs to be a balance of both.”

Nematodes. Nematodes are microscopic worms that live around or inside the plant. Some nematodes are predators while others are beneficial, eating pathogenic nematodes and secreting nutrients to the plant.

“Your soil is not one or two strains or one or two species,” Stark says. “It has thousands of species and billions of individuals in a teaspoon of healthy soil.” He says farmers should focus on building a diverse microbial portfolio.

Use a variety

“Go for diversity,” Stark says.

He says buying a single microbial or even a couple strains and thinking it will make the soil better is like buying spark plugs for a Honda Accord and thinking you’re going to win the Indianapolis 500. “You need the whole engine, each part, each microbial type works together,” Stark says.

A plant in a healthy situation spends 30% of its energy to produce food that it secretes through roots to support bacteria and fungi. “It does it because bacteria, fungi and protozoa provide food for the plant that the plant can’t normally access,” Stark explains. “So, they feed and protect each other. That is what a healthy soil does.”

Holganix Agriculture is the specific product designed for crops and is part of its Bio 800+ family of products. It contains more than 800 species of diverse, living soil microbes. The product promotes extensive root systems, Stark says, resulting in plants that are better able to find and use nutrients, minerals and water in the soil.

“By nurturing healthy plants, we help maximize yield potential while ensuring crops are better prepared to fight off and recover from seasonal stress,” he says.

The liquid concentrate not only provides microorganisms, but also eight sources of microbe food and five sources of nutrient enhancers. It includes sources such as sugar, humic acid, yucca extract and amino acids.

What to expect

Farmers looking to improve soil health by nurturing microbes may not see results above ground. “The big difference is below ground,” Stark says.

Roots will be longer, thicker and establish earlier in the season. “Deep roots are one way to build soil health by breaking up compaction layers,” Stark says. “As roots degrade, they leave space for air and water to penetrate.”

Still, there are visible signs of a healthy soil.

Soybeans will have stronger flower development resulting in more pods. Corn will see longer ears with larger diameter.

Stark contends management practices such as cover crops are a good start and provide a lot of nutrition in the field. “But not one speck goes to next year crop unless microbes can break it down to a basic chemical form that can be used by the crop,” he adds.

About the Author(s)

Mindy Ward

Editor, Missouri Ruralist

Mindy resides on a small farm just outside of Holstein, Mo, about 80 miles southwest of St. Louis.

After graduating from the University of Missouri-Columbia with a bachelor’s degree in agricultural journalism, she worked briefly at a public relations firm in Kansas City. Her husband’s career led the couple north to Minnesota.

There, she reported on large-scale production of corn, soybeans, sugar beets, and dairy, as well as, biofuels for The Land. After 10 years, the couple returned to Missouri and she began covering agriculture in the Show-Me State.

“In all my 15 years of writing about agriculture, I have found some of the most progressive thinkers are farmers,” she says. “They are constantly searching for ways to do more with less, improve their land and leave their legacy to the next generation.”

Mindy and her husband, Stacy, together with their daughters, Elisa and Cassidy, operate Showtime Farms in southern Warren County. The family spends a great deal of time caring for and showing Dorset, Oxford and crossbred sheep.

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