The next great advancement in erosion control will be microscopic, according to Julie Etra, CPESC, and a member of the International Erosion Control Association Board of Directors.

“From my perspective, what is really booming is the biology. That whole industry is exploding right now with different alternatives,” said Etra who authors a column on technology advancements for the association’s newsletter, Environmental Connection.

“It is really expanding and doing some very interesting things for sustainability,” she said.

At the top of her lists is research into Biological Soil Crusts (BSC), which occur naturally in dry parts of the world.

Microorganisms, such as cyanobacteria, lichens, bacteria, fungi and mosses, spread across the surface of the dry soil. As they grow their metabolism exudes a sticky substance which binds soil particles together, creating a wind-resistant crust across the surface of the land.

“Every year, my husband and I drive to the tip of Baja, California. There are parts of the Vizcaino Desert that are really bare. It’s extremely windy, but there is no erosion,” she said. “You can see the biological soil crusts.”

The microorganisms also produce fertilizer by absorbing nitrogen from the air—the most plentiful gas in the atmosphere—and converts it into plant-usable nitrogen.

“Basically, you have a symbiotic relationship with a number of soil microorganisms. It’s fairly complicated in cross section,” she said of the process that the various species use in combination to benefit each other.

Studies have shown that the microorganisms can make up 70 percent of the living ground cover in arid environments, as well as serve as a primary source of soil nitrogen.

“If you have a living product like this, which not only fights soil erosion but also enhances soil fertility and allows for the establishment of other plants, you’ve killed three birds with one stone,” Etra said.

So What?
The potential uses for a commercially-viable BSC mix that can be applied to the land are significant. Approximately 40 percent of the world’s landmasses are in arid to semi-arid climates. Though naturally occurring in drier climates, the bio-crusts are often inadvertently destroyed in developed areas.

A commercial product that could introduce or re-establish BSCs could find a big market in the wide expanses of arid land in the Great Basin and on military bases where wind erosion is a problem.

“I was just contacted by a gentleman from the oil and gas industry in western Colorado, looking for methods of dust control,” Etra said.

To date, the primary means to curb such soil erosion is by applying tanker trucks of water or manufactured, surface-binding agents called tackifiers, which act like a glue and sticks soil particles together.

“If you have a huge subdivision and you throw down a lot of glues, you have to come back. They last six to ten months. If anybody walks on them they don’t last at all,” Etra said.

A successfully produced BSC mix could be applied once. It gradually spreads and produces its own surface binding glue, plus a fertilizer, along the way.

The product could also find uses in areas that are experiencing lengthy drought periods, as well as those that may remain dry if projected affects of global warming come to pass.

“If the climate change projections are true and we’re going toward more desertification, we’re not going to support some of the species that we’ve got out there now,” Etra said.

Under Development
Researcher Tim Flynn, Ph.D., another member of the IECA, is developing a process to make the naturally occurring microorganisms commercially viable. Funded by a USDA Small Business Innovative Research Program grant, he has set up a research facility in western Colorado to develop a method to mass produce a mix of different species which he is testing on plots of land.

“Tim is the only person I know who is developing this commercially,” Etra said. “He’s applying them hydraulically, basically with a sprayer.”

A major breakthrough in the research has been the discovery of a method to dry the mix to preserve it. This creates a product that is similar to the dehydrated yeast used to make bread at home, according to Flynn.

“The cells are dormant when dry, but ‘wake up’ and resume growth when wet,” he said.

Another advantage to the dry form is it adds flexibility for dispersal. The mix can be either applied as an aqueous slurry, or dispersed as a dry powder, which will be a great benefit where water is too difficult or expensive to obtain.

A challenge that remains is the time it takes for the microorganisms to provide results. It took a couple of years to develop a crust in one of his western Colorado test plots, so the research is also focused on improving the growth rate. But Etra says success is on the horizon for Flynn to refine his process and proceed to market with a commercially viable mix.

“I’d say in a couple of years, if not sooner. He basically needs to get more trials out there before people will buy into it, and he will need some kind of financial support to go commercial,” she said.

It’s on the Roots
A relatively new, commercially-available product that is getting increased notice for erosion control is a naturally occurring fungus that has been around for 400 million years.

Mycorrhiza is a symbiosis found in about 95 percent of all plant families — excluding wetland plants and a few other families --and is a relatively new tool for erosion control. It boosts establishment and persistence of native and adaptive species of plants, especially on land that has no top soil or whose soil does not contain the material, according to Etra.

Often in disturbed soils, the fungus is gone. In the past, on selected projects, soil containing mycorrhiza had to be salvaged from another site and brought in.

When it is worked into the top three-inches of the soil or subsoil or otherwise applied during planting, the fungi will attach and spread over the surface or into the plant roots, depending on the type of mycorrhiza. Like the microorganisms in BSCs, it is symbiotic. “The net affect is it increases the surface area of the root exponentially,” Etra said, and therefore the plants’ capacity to take up water and nutrients.

In return, the fungi benefit from the carbohydrates produced by the plant through photosynthesis.

“One thing I try to do is encourage people to look at their disturbed sites and see what’s in the soil. Is there bacteria? Is there fungi? Then compare it to a good site,” she said.

A cautionary note: not all fungi are created equal. The quality of commercial mycorrhiza is not regulated like seed for planting. There are different varieties of this age-old and beneficial fungus which are adapted to different plants. When buying a commercially produced mix, ask questions.

“It might be loaded with all kinds of mycorrhiza, but a lot of them may be inappropriate for your use,” Etra said.

A Change in Course
The commonality between these two types of products—BSCs and mycorrhiza—is that they are naturally occurring organisms that symbiotically support plant life, making them sustainable. They are also cost effective. In the process, they provide levels of erosion control and aid native and adaptive species to thrive and hold soil in place.

That is the future for erosion control, according to Etra. She maintains that these types of products—besides their immediate, on-site benefits--provide an alternative to standard commercial fertilizers, which should be phased out because of the demands they pose on two critical global resources.

“If you look at the enormous amount of energy and water that it takes to produce them, many of our environmental problems are caused by our over use of fertilizers,” she said. “Our tools can become pollutants.” SLDT