Stahl: Microorganisms provide essential benefits to soil health and productivity

Casper – On earth, soil is the habitat with the greatest diversity of organisms and is where most organisms spend their lives, said Peter Stahl, University of Wyoming (UW) soil ecology professor. 

During a soil health workshop, Stahl described different types of microorganisms in soil and the benefits the microorganisms provide to soil health and producers, as well.

“Just one teaspoon of soil contains millions of microorganisms and thousands of meters of fungal hyphae,” Stahl stated.

A variety of organisms live in soil, including nematodes, amoebae, flagellates, bacteria, fungi and much more, noted Stahl.

He mainly discussed the benefits different types of bacteria and fungi provide for plants and soil health.

Bacteria

There are thousands and thousands of bacterial species in every type of soil, and they are the key players in soil health, Stahl stated.

“Bacteria are the smallest and most abundant organisms in soil, which are found in concentrations of over a billion in one teaspoon of soil,” Stahl added. “Bacteria are extremely important in the cycling of nutrients and the transformation of soil carbon to soil organic matter, which increases soil health and productivity.”

Stahl describes bacteria as capsules of biochemical activity that absorb nutrients, break down soil organic matter and convert ammonia, a form of nitrogen from decomposition, into nitrogen plants can absorb.

“Plants and bacteria have a reciprocal relationship because bacteria process nitrogen so it is available for plants, and then, plant roots produce energy-rich compounds to feed bacteria,” mentioned Stahl.

Most organisms, including bacteria, live in the space between soil particles called pore space, which makes up 50 percent of the soil structure.

“Producers need to manage soil structure to maximize the pore space for soil microorganisms, like bacteria, to live,” Stahl stated. “Reducing compaction increases the pore space and increases soil health.”

The most activity from bacteria and other microorganisms is in the top soil, and as the depth increases, soil becomes drier so microbial activity decreases, according to Stahl.

Fungi

Stahl mentioned fungi are also very abundant in soils, and in some soils, only plant roots are more abundant than fungal hyphae, described as finger-like projections that absorb nutrients.

“Primarily, fungi make a living from decomposing dead plant materials using hyphae to grow into roots, stems and leaves,” Stahl stated. “Due to the hyphae, fungi can transport nitrogen from the soil into decomposing plants to help feed themselves and break down more plant material.”

One major type of fungi that is very beneficial is mycorrhizal fungi, which form symbiotic relationships with almost all plant roots.

“Mycorrhizal fungi act as an extension of a host plant’s root system and allow the fungi to extract nutrients and water from a larger area around the root system,” Stahl explained. “Almost all the water and nutrients from the soil are transported by the fungi, especially in grass roots, which is important in semi-arid prairie plants,” Stahl noted.

To sustain mycorrhizal fungi, healthy plant populations above ground need to be maintained, he added.

“Plants are the primary producers that create carbon dioxide, make organic compounds and provide plant biomass, which are eventually recycled by fungi, bacteria and other microorganisms,” Stahl stated. 

The fungal hyphae hold soil particles together, which facilitate and maintain soil structure, said Stahl, noting, “Basically, the fungal hyphae act almost like a biological rebar systems in the soil.”

Other microorganisms in the soil include nematodes, psyllids, euglenoids and springtails or fungus gnats, which are common in Wyoming soils, according to Stahl, noting nematodes are worm-like organisms that can be a big problem for sugarbeet producers.

“Scientists are still trying to get a grip on microorganisms, but they are really important for maintaining soil structure, cycling nutrients and decomposing dead plant materials, so plants can be productive,” Stahl added.

Peter Stahl presented during a soil health workshop at the 2017 Wyoming Natural Resources Rendezvous on Nov. 28 in Casper. 

Heather Loraas is assistant editor of the Wyoming Livestock Roundup and can be reached at heather@wylr.net.