Getting to the root of soil function

Lance Gunderson paired with Byron Seeds to talk about soil function at four seminars Jan. 16-19 in central Minnesota.

“It’s one of those things where we probably know more about the ocean floor than we do soil microbes, but they play a really important role in what we try to do as growers and plant managers,” Gunderson said. “I call (microbes) soil livestock.”

Gunderson, M.S., Ph.D. candidate, is the president and co-owner of Regen Ag Lab.

During the first part of the seminar, Gunderson talked about microbes found in soil and their functions, starting with bacteria. 

“There are 100 million bacteria in a teaspoon of soil,” Gunderson said. “The primary role of bacteria is to break down simple carbon compounds.”

Bacteria also work with nitrogen. Some perform nitrogen fixation while others do denitrification. While most of the bacteria in soil will not harm crops, there are a few pathogens. The majority fight pathogens and create antibiotics to protect the plant.

“Most of the microbes rely on the plant to provide them food,” Gunderson said. “That is important because they don’t want to kill the plants.”

Lithotrophs are bacterium that can break down rocks, but they need to have a strong connection to plant roots. When geology and biology are combined, soil is created.

A benefit of fungi is that they strangle nematodes that hurt plants and consume them.

“The fungus is trying to protect the same thing you are, your crop,” Gunderson said. “The role of fungi is for the breakdown of complex carbon compounds.”

The fungi transport nutrients to the crops because they want them to grow, to collect more energy from the sun and air, and leak some to the fungi. This process is not specific to fungi.

Fungi play an important role in carbon storage and soil structure.

“Fungi grow like a net,” Gunderson said. “Fungi don’t like tillage. Because of this, when you till the soil, it’s like driving a bulldozer through your house. Bacteria don’t care; it’s like going to an amusement park for them.”

If fungi can build a good soil structure, the soil’s drought resilience will increase. Roots will only grow in an area where oxygen and moisture are present. Tillage can negatively impact this.

“It’s what you do after the tillage that makes all the difference,” Gunderson said.

If no new living roots are planted into the tilled soil, there is a risk of a hard pan or crust developing. It is best to till and plant immediately after to ensure roots will grow again to keep movement within the soil.

Continuously having plants also helps to shade the soil and keep soil temperature down, which is important for the enzymes — functional proteins — in the soil.

“We start to see a decrease (in enzymes) when soil temperature is above 90 degrees,” Gunderson said. “Once we hit above 105 degrees, they just fall off. They unfold and break down and aren’t functional anymore.”

Enzymes are necessary to break down compounds and make nutrients more available to microbes and plants. Getting carbon is the biggest part of soil function. However, carbon cannot only be captured. It needs to be cycled through the air, plant and soil.

“It’s all about energy, and the microbes need energy just like we do,” Gunderson said. “Almost 50% of all the energy captured by the crop is leaked into the ground. It does this because most plant roots aren’t efficient at getting nutrients out of the soil. The microbes are the gatekeepers for that.”

The less downtime between crops, the better it is for the soil.

“If you can get more photosynthesis happening, you will feed this community (of microbes),” Gunderson said. “The fatter your soil is the more life it has.”

During the second half of the seminar, Gunderson focused on the cost of production. 

“There are two ways to make money in any business: You can increase gross revenue or decrease expenses,” Gunderson said. “(Farmers) always had a message to drive more, to push production. However, we produce 2.5 times the amount of food for everyone on the planet.”

Producers do not need to push for bigger yields but rather find ways to reduce expenses while producing a crop, even if the yield is not as high as in previous years.

“I can’t remember how many times I got a call from farmers saying, ‘Lance, I don’t know what I’m going to do next year,’ and my heartstrings are pulled,” Gunderson said. “(Producers) are told they need to feed the world, but we don’t care if you can feed yourself. Align yourself with companies that align with you.”

Gunderson focused on how producers should prioritize a reduction in their coefficient of performance, whether this is accomplished by planting cover crops, using less fertilizer or eliminating fertilizer some years.

“Don’t buy all the extra stuff that you don’t get anything from,” Gunderson said. “Evaluate your soil to understand where you are getting benefit return.”

Using cover crops helps because they put nutrients into play. Through the breakdown of the cover crop, nutrients return to the soil as plant-available nutrients. A true cover crop will never leave the field and can be utilized for livestock through grazing.

“Grazing it will speed up the cycle, and 95% of nutrients the cow takes in will end up back into the soil,” Gunderson said. “Livestock will be the digester for you.”

Plants and soil need to be fed different nutrients just like cows need a balanced diet. While producers and plants provide the microbes with the compounds, they will get it where it needs to be in the right form.

“(Microbes) are the mafia of the soil,” Gunderson said. “They need a balance between energy and protein. If you don’t feed them a balanced ration, they are going to tie up what they are lacking and hold it until the plants, or you, provide it.”