The findings suggest that specific bacteria inhabit specificlocations in soil and thus different groups and species can becarried away depending on the kinds of particles that erode. It s important to know which microbes are being lost fromsoil, says Acosta-Mart nez, a soil microbiologist and biochemistat the USDA-ARS Cropping Systems Laboratory in Lubbock, TX, because different microbes have different roles in soilprocesses. For example, the Proteobacteria a diverse group critical to carbonand nitrogen cycling were more associated in the study witheroded, coarse particles (those larger than 106 microns in size)than with the fine dust. Similarly, the dust housed its owncommunity, in this case Bacteroidetes and other bacteria that areknown to tolerate extreme dryness, gamma radiation and other harshconditions that may develop on dust particles as they float throughthe air, says Gardner, a postdoctoral researcher who is alsoaffiliated with Alabama A&M University. What this means is that wind erosion can both reduce the overallmicrobial diversity in farm fields, as well as deplete topsoil ofspecific groups of essential bacteria, say the researchers.
At thesame time, certain important groups, such as Actinobacteria thatpromote soil aggregation, remained in the parent soil despite theerosive conditions generated in the wind tunnel. And while finedust can travel extremely long distances, coarse particles rarelymove more than 20 feet, suggesting that they and their associatedmicrobes should be fairly easy to retain with cover cropping andother soil conservation measures, Acosta-Mart nez notes. Helping farmers and land managers adopt practices that betterconserve soil is one of the main goals of the USDA-ARS team swork, which also includes Ted Zobeck, Scott Van Pelt, Matt Baddock,and Francisco Calder n. In the Southern High Plains region, forexample, intense cultivation of soil combined with a semi-aridclimate can result in serious wind erosion problems. In fact, lastsummer s drought brought Dust Bowl-like conditions to the area,http://www.scarpehoganscarpeit.com/,says Acosta-Mart nez.
But wind erosion is a national problem, she adds, withsignificant erosion occurring even in places where the growingseason is humid and wet. Organic histosol soils in Michigan andmany other parts of the country, for instance, are very susceptibleto wind erosion when dry, especially since they re usuallyintensively farmed and often left bare in winter. Cover cropping orcrop rotations not only help keep these soils in place, but canalso build soil organic matter, which in turn promotes soilaggregation, water penetration,http://www.cheapmbtshoesukmbtoutlet.co.uk/, and general soil health. It can take years, however, for farmers who ve adopted newmanagement practices to detect noticeable changes in levels of soilorganic matter and other traditional soil quality measures. This iswhy Acosta-Martinez and Gardner have been analyzing soils withpyrosequencing, a method that yields a fingerprint of an entiremicrobial community, and well as identifies specific groups andspecies of bacteria based on their unique DNA sequences.
In this study, these microbial signatures told the researcherswhat s potentially being lost from soil during wind erosionevents. But the fingerprints can be early indicators of positiveoutcomes, too. The microbial component is one of the most sensitive signaturesof changes in the soil, says Acosta-Mart nez, because ofmicrobes involvement in soil processes, such as carbonaccumulation and biogeochemical cycling,http://www.cheapairjordanshoeok.com/. So, we re looking forany shifts in these signatures that could lead us to think thatthere are benefits to the soil with alternative management.
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