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| Titel |
New approach to measure soil particulate organic matter in intact samples using X-ray computed micro-tomography |
| VerfasserIn |
Alexandra Kravchenko, Wakene Negassa, Andrey Guber, Sonja Schmidt |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250088299
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| Publikation (Nr.) |
 EGU/EGU2014-2389.pdf |
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| Zusammenfassung |
| Particulate soil organic matter (POM) is biologically and chemically active fraction of soil
organic matter. It is a source of many agricultural and ecological benefits, among
which are POM’s contribution to C sequestration. Most of conventional research
methods for studying organic matter dynamics involve measurements conducted on
pre-processed i.e., ground and sieved soil samples. Unfortunately, grinding and sieving
completely destroys soil structure, the component crucial for soil functioning and C
protection. Importance of a better understanding of the role of soil structure and of the
physical protection that it provides to soil C cannot be overstated; and analysis of
quantities, characteristics, and decomposition rates of POM in soil samples with intact
structure is among the key elements of gaining such understanding. However, a marked
difficulty hindering the progress in such analyses is a lack of tools for identification
and quantitative analysis of POM in intact soil samples. Recent advancement in
applications of X-ray computed micro-tomography (μ-CT) to soil science has given an
opportunity to conduct such analyses. The objective of the current study is to develop a
procedure for identification and quantitative characterization of POM within intact
soil samples using X-ray μ-CT images and to test performance of the proposed
procedure on a set of multiple intact soil macro-aggregates. We used 16 4-6 mm
soil aggregates collected at 0-15 cm depth from a Typic Hapludalf soil at multiple
field sites with diverse agricultural management history. The aggregates have been
scanned at SIMBIOS Centre, Dundee, Scotland at 10 micron resolution. POM was
determined from the aggregate images using the developed procedure. The procedure
was based on combining image pre-processing steps with discriminant analysis
classification. The first component of the procedure consisted of image pre-processing
steps based on the range of gray values (GV) along with shape and size of POM
pieces. That was followed by discriminant analysis conducted using statistical and
geostatistical characteristics of POM pieces. POM identified in the intact individual soil
aggregates using the proposed procedure was in good agreement with POM measured in
the studied aggregates using conventional lab method (R2=0.75). Of particular
importance for accurate identification of POM in the images was the information
on spatial characteristics of POM’s GVs. Since this is the first attempt of POM
determination, future work will be needed to explore how the proposed procedure
performs under a variety of potentially influential factors, such as POM’s origin and
decomposition stage, X-ray scanning settings, image filtering and segmentation methods. |
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