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| Titel |
Heterogeneity of soil properties along a profile as reflected in multifractal analysis |
| VerfasserIn |
Eva Vidal Vazquez, Sidney R. Vieira, José G. V. Miranda, Otavio A. Camargo, João R. F. Menk, Jorge Paz Ferreiro |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250038930
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| Zusammenfassung |
| Soils have been defined as natural bodies that have length, breadth and depth. Each
soil type occupies a portion of the landscape. Soil properties are the result of soil
forming factors and processes that operate at different spatial scales. Therefore, there
is a need to take into account spatial scales and the processes operating at those
scales for a sound characterization of the spatial variability of soil properties. The
capability of multifractal analysis to efficiently describe and summarize patterns of soil
spatial variability has been demonstrated in the last years. The objectives of this
work were (a) to characterize the spatial variability and scaling of soil properties
along a transect using multifractal techniques and (b) to relate the pattern of spatial
variability with soil forming factors and processes. The research site was located at the
experimental centre of the Agronomic Institute of Campinas, São Paulo State, Brazil.
The topography of the site is gently undulating. The climate is humid subtropical
(Cwa according to Köppen). A transect of 2370 m was established and a 30 m
sampling interval was marked along it, giving 79 sampling points. This profile included
different soil types and soil uses. The most frequent soil type was Oxisol according
to the Soil Survey Staff equivalent to a Latossolo in the Brazilian classification
system. Soil was sampled at the 0-20 cm depth and the following properties were
determined: texture fractions, pH both in H2O and KCl, organic carbon content (OC),
exchangeable bases (S), exchangeable aluminium and hydrogen, cation exchange
capacity (CEC) and percent base saturation (V). The texture along the studied transect
ranged from clay to sandy-clay. Soil pH (H2O) ranged from strongly acid (4.50)
to neutral (7.00) with a mean value of 5.21. Accordingly percent base saturation
varied between 4.0 % and 91.7 % and on average it was 38.2 %. Mean organic
carbon content was 1.66% and the extreme values were 0.80 % and 2.60%. The
statistical variability of the studied soil properties ranked as follows: V > silt >
clay > S > OC content > sand > pH. The experimental data were converted into
distributions of mass along a geometric support, i.e. mass content per segment of
30 m size, to perform multifractal analysis. Next, a probability distribution was
obtained by dividing the values of the measure in a given segment by the sum of the
measure in the whole transect. The spatial pattern of the studied soil properties showed
multifractal scaling. Multifractal behaviour was well characterized and expressed
through the next functions: singularity spectra, f(α), moment scaling exponent, Ï(q),
and generalized dimension, D(q). There were, however, differences in the degree
of power law scaling between the studied soil properties. Our study showed that
the multifractal parameters derived from f-α, Ï-q and D-q relationships clearly
summarized the spatial pattern of variability of the studied soil properties. The observed
scale-dependent relationships demonstrate the usefulness of the multifractal techniques to
analyze the effect of soil forming factors and processes on the patterns of soil spatial
variability.
Acknowledgement: This work was supported by Spanish Ministry of Education (Project
PHB2009-0094-PC) and CAPES from Brazil. |
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