Thank the soil, and soil bacteria


Nitrogen’s an important element, and not just for farmers and gardeners. It makes up roughly 3 percent of the human body, and two-thirds of the atmosphere’s air.

Most living things need nitrogen, but many, including humans, can’t pull it from the air. That is where the soils mini-but-mighty microorganism community steps in.

In Central Montana, Jed Eberly is the one to ask about life in the soil. He’s an assistant professor of agronomy and soil microbiology who works at the Central Agricultural Research Center outside of Moccasin.

“Nitrogen is one of the fundamental elements in all living organisms. Every protein in our body has nitrogen in it,” he said. “Nitrogen as nitrogen gas can’t be used by plants of animals directly.”

Plants and animals need to be thankful for more than just the element, though. Without certain dirt denizens, Eberly said plants wouldn’t have access to usable forms of the element. This is really important for farmers and their consumers.

“Nitrogen is one of the most essential nutrients in terms of success of crops,” he said. “Wheat, for example: less nitrogen means your protein levels will be really low.”

Microorganisms play a vital role in giving plants, and in turn, the animals that eat them, access to nitrogen from the air. These tiny soil-dwellers also make sure nitrogen is recycled. Think, for example, of all the nitrogen used to make grain crops. After harvest, what happens to the nitrogen in the stalks? Does it go to waste?

“If you had sterile soil, soil with no microorganisms in there, the stubble would lay there for years and years,” Eberly said.

Luckily, there are plenty of microorganisms. Nitrogen mineralization takes the nitrogen in biological matter and makes it available for us by plants again. Eberly said it’s one small step in breaking down the material, but an important one. There are families of bacteria in the soil that focus on nitrogen mineralization.

“They’re taking nitrogen from the biomass, and making it available to the plants again,” he said.

Eberly said these bacteria need certain working conditions, including temperature. They’re the most efficient from 68-95 degrees, slowing down dramatically in lower temperatures. They also need moisture. Most important, though, is biodiversity, according to Eberly.

“Many of these microorganisms function best in a community of other organisms,” Eberly explained. In fact, some of them may not function by themselves.”

He explained the families of bacteria are very specialized. Just like it takes a chain of people all working different jobs to transform grain into the bread, it takes a combination of specialized microorganisms to turn the nitrogen in dead plants or animals back into a usable form.

“The microorganisms may need other things only available from other bacteria,” he said. “In a microorganism community in the soil, we’re talking potentially thousands of different organisms, each with a different function that’s necessary to the community as a whole.”

So thank the soils once in a while.



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