Going Green

Friday, October 18, 2019

OSU’s Wilson finds fungi a vital link to keeping soil healthy

With the devastating Amazon rainforest fires still burning, climate concerns are back in today’s political spotlight. But they have been on the front burner at Oklahoma State University’s Division of Agricultural Sciences and Natural Resources for a long time.

“Since the Industrial Revolution, humans have been converting carbon from the geologic pool into the atmosphere at an astounding rate,” said Gail Wilson, holder of the Sarkeys Distinguished Professor of Rangeland Soil Ecology within OSU’s Department of Natural Resource Ecology and Management. “The carbon existed before it was converted from a solid or liquid state into a gaseous state, of course, but its release as greenhouse gases is having an effect that for the most part is not beneficial to humans or the world’s ecosystems.”

As a scientist, Wilson is among those striving to find ways to ease the negative consequences. In her research, thinking small is laying the groundwork for possible applications that landowners, agricultural producers and other natural resource managers can do for a potentially significant positive effect.

“Soil aggregation and carbon sequestration are tightly correlated with the abundance of arbuscular mycorrhizal fungi, the focus of my research for more than a decade,” she said. “These fungi form symbiotic associations with the roots of more than 80 percent of land plants. Science is showing they are essential to both healthy plant and soil development, and they play a major role in taking carbon out of the atmosphere.”

While many people have heard about carbon sequestration — capturing atmospheric carbon and storing it long term — fewer are aware of the importance of soil aggregation.

Soil aggregation is the arrangement of soil particles, influencing virtually all nutrient cycling processes and biological life in soils.

“Most people are not aware the biodiversity in one handful of soil is equivalent to the biological diversity in a rainforest,” Wilson said. “The biodiversity in soil declines, sometimes drastically, as soil degrades. The bottom line is we need to repair the soil if we are to promote the plants that grow in the soil. It’s all interconnected.”

That is where Wilson’s research into arbuscular mycorrhizal fungi comes in, improving scientific understanding of interrelationships that could help lessen the greenhouse gas problem from the ground up. Wilson and her cooperating scientific investigators have been particularly interested in the role played by grasslands, such as those present throughout America’s central Great Plains region.

Best management practices

Approximately a third of the world’s land surface is grasslands. Wilson said those who manage grasslands as part of the world’s food production system are key players in the fight to lessen the negative effects of climate variability. As an example, grazing animals have evolved in a symbiotic relationship with grasslands.

“Beef cattle grazing on grass pastures might not be the first thing many people think of when discussing the subject of combating greenhouse gas emissions, but it is an agricultural practice that scientific studies have shown can provide significant dividends, especially when considering the world cannot allow land to go to waste if it is to feed a projected population of 10 billion people by 2050,” Wilson said.

Research by R.F. Follett and D.A. Reed published in 2010 examined the effects of grazing on organic carbon storage in the soil of North American rangelands. Follett and Reed found impacts ranging from no change to up to 268 pounds of carbon stored per acre per year.

“The variability of the impact grazing can have on carbon sequestration is due to differences in specific grazing management practices from operation to operation,” said Sara Place, a former OSU animal scientist and current senior director of sustainable beef production research with the National Cattlemen’s Beef Association.

The number of cattle grazed per acre, fertilization and prior land use all can affect how much carbon is stored.

“While changes in carbon sequestration due to grazing or other management decisions may be relatively minor on a per-acre basis, they can translate into significant impacts if implemented on a large scale given the number of acres of grassland in the world,” Place said.

What about methane emissions from cattle? The U.S. Environmental Protection Agency estimates direct emissions from America’s beef industry account for about 2 percent of the nation’s total greenhouse emissions. Throw in the fact that Oklahoma’s beef industry adds more than $3.7 billion annually to the state economy, and cattle producers who employ research-proven best management practices are having a significant positive effect on many fronts.

“A University of Wyoming study published in 2019 indicated the ecosystem services of cattle ranching and farming conservatively provide $14.8 billion of societal value in the United States,” Place said.

Research by R. Lal published in 2011 indicated if soil organic carbon in agricultural ecosystems and grasslands could be increased by 10 percent globally during the 21st century, the atmospheric concentration of carbon dioxide could be reduced by 100 parts per million.

In addition, pasture and grasslands account for approximately 27 percent of the land area in the United States. Avoiding the conversion of this land to tilled cropland and residential uses could help prevent further increases in greenhouse gas emissions.

Wilson loves to point out that grasslands — and the animals that graze them — fill a necessary niche on planet Earth. Unfortunately, when it comes to grasslands, soil conditions have become somewhat degraded. Therefore, to maximize the carbon sequestration potential of grasslands, it is vital good soil conditions be promoted.

“That brings us back to arbuscular mycorrhizal fungi and the important role they play in healthy grasslands,” Wilson said. “We have been losing topsoil a hundred times faster than it is formed. That is not sustainable. But the solution may lie in the fungi. That is why our scientific research is necessary, and why it should be important to everyone.”

Student opportunities

Scientists tackling the problem are not limited to Wilson and her peers, of course. There are graduate assistants and undergraduate students working alongside faculty and staff. At any given time, Wilson has had up to five undergraduates conducting research through her lab since joining the OSU faculty 12 years ago.

“Undergraduates tend to become especially interested in certain parts of ongoing projects,” she said. “Most take ownership of those aspects and enthusiastically want to take on challenges specific to those aspects. I like to individualize their research as much as possible, matching it as closely as possible to whatever caught their interest, within the bounds of the overall project.”

Typically, Wilson teams the undergraduate with a graduate student working in the lab, believing it to be a “win-win situation.” The end result often has been a project’s research findings being published in a higher-tier scientific journal than originally projected.

“Scientific awareness needs to advance, so the more prestigious the publication, the better that is accomplished,” Wilson said. “It’s incredibly valuable to the reputations and eventual careers of the individual students themselves. I believe it’s important we promote such résumé-building opportunities while honing good research methodology and understanding.”

The team concept also enhances teaching and supervisory experiences as the graduate student is the senior member and often fills a big sister or big brother mentorship role, distinct from what a faculty or staff member might provide as a lab manager. Wilson said her graduate students quickly buy into how much fun it is to work with undergraduates, who may not be all that experienced when they start but are generally enthusiastic to learn and improve.

“Young undergraduates come to college somewhat programmed into asking, ‘What is the correct answer?’” Wilson said. “Science is investigation, and to see their enthusiasm and commitment as undergraduates discover they are detectives in the midst of a mystery is fun and fulfilling for me and the graduate students. There comes a point where the undergraduates realize what is not known and commit to work through the process, and then come to the realization they can handle the responsibilities of being the detective, of being the scientist.”

That is good for everyone: the scientific community, academia and the general public, now and in the future.

“Want to fight the negative effects of climate variability?” Wilson asked. “Have we got some fungi for you.”