Frontiers in Soil Science Research Report of a Workshop (2009) / Chapter Skim
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3 Summary of Presentations
3 Summary of Presentations
Pages 13-30
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From page 13... ...
Chapter 4 summarizes the key points that were made during the workshop. Session 1: Using Tracers to Understand Soil Processes Susan Trumbore, University of California, Irvine, discussed the use of transient isotopic tracers on land to quantify and better understand soil processes and how they interact.
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From page 14... ...
Some of the reasons that tracers are not more widely used include a lack of understanding in the scientific community of the potential use of tracers to address soil science questions, a perceived expense of isotope measurements, and the need for geochemists familiar with tracer methods to work with soil scientists in defining questions that the use of tracers can answer. Trumbore suggested that a combination of recent methodological advances and framing of critical questions makes this an appropriate time for a more systematic application of a suite of tracers to study problems in soil science.
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the global carbon cycle integrated across multiple timescales and the associated fundamental processes of carbon cycling in soil and (2) separating soil formation and degradation processes across spatial and temporal scales.
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These nanoscale processes can be manifested as phenomenological observations at the field and landscape scales; however, there are challenges to linking observations at these various scales. Fendorf illustrated that advances during the past decade in microscopic and spectroscopic techniques, particularly those allowing for the interrogation of soil materials in situ, have greatly advanced our ability to elucidate complex coupled hydrobiogeochemical processes leading to the sorption or release of ions and chemicals.
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From page 17... ...
Donald Sparks commented that the Critical Zone should be a focus in many geosciences leading to a better understanding of physical, chemical, and biological processes over many scales. He emphasized the importance of reactions at the interfaces, especially the microbe-mineral interface and the root-soil interface.
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From page 18... ...
Environment relates to understanding how organisms interact with their environment -- including physical space, chemical conditions, and interactions with other biological entities and their effects. Tiedje discussed a series of four questions regarding our understanding of the soil biological frontier, with examples given or research needs identified, or both, for each question.
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From page 19... ...
Tiedje also noted that the soil community is more than bacteria; it also includes a diversity of animals, fungi, protozoa, archaea, and viruses. These organisms interact in soil food webs to regulate soil microbial activity and diversity.
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As an example, biofilms have high heterogeneity represented by high activity in localized environments. In nature, biofilms grow on active substrates that serve either as electron acceptors or donors, and this needs to be incorporated into research on function in the soil environment.
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Centre, University of Abertay, Scotland, noted in his presentation that their center was designed specifically to encourage interdisciplinary research to examine how a heterogeneous architecture affects biological function and whether that biological function influences architecture. In situ soil architecture has a determining effect on soil physical, chemical, and biological processes.
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From page 22... ...
In addition, soil features, such as clay coatings and iron mottling, provide permanent signatures in the soil that can be "read" by trained pedologists, again indicating water flow patterns and estimates of the associated biochemical processes, such as oxidation and reduction. During the discussion, it was brought out that boundary conditions of the soil system, particularly conditions at the soil surface, have a major effect on soil processes.
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From page 23... ...
His presentation focused on water cycling (hydrological processes) , carbon cycling, and trace gas fluxes as examples of the inherent complexity of upscaling soil processes to regional scales.
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From page 24... ...
Instrumentation offers rapid sampling rates to be used with eddy correlation and flux gradient techniques. In the estimation of trace gas fluxes, there is an exciting opportunity for collaboration among soil scientists, meteorologists, and atmospheric chemists to improve the understanding of the upscaling of nitrous oxide production from the microbial to the regional scale.
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From page 25... ...
In quoting Izaurralde's comment on the inherent complexity of upscaling soil processes to regional scales, she questioned whether there is an optimal scale for remote sensing. The data are available; they just need to be used, which can lead to breakthroughs in soil modeling.
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From page 26... ...
Session 7: Key Indicators for Detecting the Resilience and Stability of the Soil System The multitude of ecosystem services that soils provide is increasingly recognized in the context of sustainable agriculture, climate change, desertification, and other global phenomena. The resilience of terrestrial, and some aquatic, ecosystems in the face of intensifying human disturbance relies, in part, on structural and functional attributes of soil.
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From page 27... ...
The resulting changes will in turn affect other systems -- hydrosphere, atmosphere, biosphere, as well as human beings. Scow's presentation focused on the challenges of defining soil indicators that diagnose problems before they manifest into real damage that seriously impairs soil function.
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Scow categorized indicators into four types: 1. Physical: water retention and transmission, soil structure 2.
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soil function, including soil structure, processes, and biotic activity -- the first two being relatively well known, but biotic activity is difficult to assess. Birl Lowery, University of Wisconsin, Madison, discussed how maps can be useful indicators of, for example, soil quality and contamination.
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From page 30... ...
1998. Relationships between soil organic carbon and soil quality in cropped and rangeland soils: the importance of distribution, composition and soil biological activity. Pp. 405-425 in Advances in Soil Science: Soil Processes and the Carbon Cycle, R
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