Biogeochemistry and microbial ecology of Amazonian Dark Earth Soils.
CALS Impact Statement
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Overview
abstract
Through use of molecular techniques and traditional approaches, we are characterizing the bacterial and fungal communities in Amazonian Dark Earths (ADE) and adjacent Oxisols to identify organisms uniquely associated the ADE that may contribute to their enhanced fertility and sustainability.
The Amazonian Dark Earths range in age from a few hundred to over 6000 years before present. These are anthropogenic soils arising from the soil management practices used by the Indio population that was native to this region. These soils are scattered in patches on the high bluffs throughout the Amazon River Basin. They are unique because they have a high black carbon content, which is related to their high and stable fertility. Because they have an unusual chemistry, they are also likely to harbor unique biota with novel capabilities. Studies of these soils have been hampered by lack of training of in-country personnel, restricted movement of soil material and remoteness of many of the soils locations. The soils have both anthropological and scientific significance. From a scientific perspective, increased understanding of the mechanisms responsible for their high fertility and resilience may help us design farming systems for increased productivity and sustainability.
response
We have established collaborative relationships with researchers at the University of Sao Paulo, the Center for Agriculture and Nuclear Energy (CENA) in Saõ Paulo and the Center for Biodiversity of the Amazon (CBA) in Manaus. In conjunction with our collaborators, Amazonian Dark Earths (ADE) and adjacent background soils have been sampled from a range of sites in the Manaus region of Brazil over the past two years. We have conducted analyses to evaluate the abundance, activity and diversity of bacteria, archaea and fungi in these soils. Cloning and sequencing of organisms unique to ADE has been undertaken in collaboration with CENA. We initiated and conducted a training course in molecular soil ecology methods in collaboration with colleagues at CBA so that our collaborators could undertake this work in-country, thus helping to overcome restrictions imposed by biodiversity regulations. To date, we have trained 12 collaborators from 7 institutions in Brazil. This course was so successful that we have been invited back next year and have already received funding through an American Society for Microbiology International Professorship grant to accomplish this. Our analyses of microbial communities are ongoing. Once the microbial census is complete, the biochemistry of unique community members will be undertaken.
impact assessment
We have established excellent collaborative relationships with several key research organizations in Brazil. We have trained 24 researchers from 11 Brazilian scientific institutions in molecular methods for studying soil ecology, with particular emphasis on ADE soils. Our analyses of microbial communities in ADE soils have revealed organisms that are uniquely adapted to these soils and that have a low similarity to other organisms known to science. Identifying the unique organisms that inhabit these unusual soils is helping to elucidate the roles they play in stabilizing the fertility of ADE over the hundreds to thousands of years of their existence. Our joint work aims to enhance the research capacity of our collaborators in Brazil so that they can undertake similar studies.
funding source description
American Society for Microbiology, Latin America Professorships
