Agricultural bacteria: Blowing in the wind
Helping farmers and land managers adopt practices that better conserve soil is one of the main goals of the USDA-ARS team’s work, which also includes Ted Zobeck, Scott Van Pelt, Matt Baddock, and Francisco Calderón. In the Southern High Plains region, for example, intense cultivation of soil combined with a semi-arid climate can result in serious wind erosion problems. In fact, last summer’s drought brought Dust Bowl-like conditions to the area, says Acosta-Martínez.
But “wind erosion is a national problem,” she adds, with significant erosion occurring even in places where the growing season is humid and wet. Organic histosol soils in Michigan and many other parts of the country, for instance, are very susceptible to wind erosion when dry, especially since they’re usually intensively farmed and often left bare in winter. Cover cropping or crop rotations not only help keep these soils in place, but can also build soil organic matter, which in turn promotes soil aggregation, water penetration, and general soil health.
It can take years, however, for farmers who’ve adopted new management practices to detect noticeable changes in levels of soil organic matter and other traditional soil quality measures. This is why Acosta-Martinez and Gardner have been analyzing soils with pyrosequencing, a method that yields a fingerprint of an entire microbial community, and well as identifies specific groups and species of bacteria based on their unique DNA sequences.
In this study, these microbial signatures told the researchers what’s potentially being lost from soil during wind erosion events. But the fingerprints can be early indicators of positive outcomes, too.
“The microbial component is one of the most sensitive signatures of changes in the soil,” says Acosta-Martínez, because of microbes’ involvement in soil processes, such as carbon accumulation and biogeochemical cycling. “So, we’re looking for any shifts in these signatures that could lead us to think that there are benefits to the soil with alternative management.”