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| Titel |
The added value of biomarker analysis to the genesis of Plaggic Anthrosols. |
| VerfasserIn |
Jan van Mourik, Boris Jansen |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250102164
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| Publikation (Nr.) |
 EGU/EGU2015-1445.pdf |
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| Zusammenfassung |
| Coversands (chemical poor Late-glacial aeolian sand deposits) dominate the surface geology
of an extensive area in northwestern Europe. Plaggic Anthrosols occur in cultural landscapes,
developed on coversands. They are the characteristic soils that developed on ancient fertilized
arable fields. Plaggic Anthrosols have a complex genesis. They are records of aspects
environmental and agricultural history. In previous studies information of the soil
records was unlocked by application of pollen analysis, 14C and OSL dating. In this
study we applied biomarker analysis to unlock additional information about the
applied organic sources in the production of plaggic manure. Radiocarbon dating
suggested the start of sedentary agriculture (after a period, characterized by shifting
cultivation and Celtic fields) between 3000 and 2000 BP. In previous studies is assumed
that farmers applied organic sods, dug on forest soils and heath to produce organic
stable manure to fertilize the fields. The mineral fraction of the sods was supposed
to be responsible for the development of the plaggic horizon and the raise of the
land surface. Optically stimulated Luminescence dating however suggested that
plaggic deposition on the fields started relatively late, in the 18th century. The use of
ectorganic matter from the forest soils must have been ended in the 10th-12th century,
due to commercial forest clear cuttings as recorded in archived documents. These
deforestations resulted in the first extension of sand drifting and famers had to protect the
valuable heath against this ´ environmental catastrophe´ . The use of heath for
sheep grazing and other purposes as honey production could continue till the 18th
century, as recorded in archived documents. In the course of the 18th century, the
population growth resulted in increasing demand for food. The deep stable economy was
introduced and the booming demand for manure resulted in intensive sod digging on the
heath. This caused heath degradation, resulting in the second extension of sand
drifting. To improve our knowledge about the evolution of plaggen soils we can
combine data of pollen and biomarker spectra of samples of plaggic deposits. Species,
present in pollen spectra of plaggic deposits, can have three sources: 1. Pollen,
already present in sods, used in the stable to produce manure. 2. Pollen, originating
from flowering crop species. 3. Pollen, originating from flowering species in the
surroundings. Species, present in biomarker spectra, can have three sources: 1.
Biomarkers from tissues, present in sods, used for manure production. 2. Biomarkers from
decomposed roots of crop species. 3. Biomarkers from straw of crop species, used in
the stable for manure production. Comparison pollen and biomarker spectra of
samples of a regular Anthrosol (Posteles, NE-Netherlands) and a Buried (Nabbegat,
SE-Netherlands, buried around 1800 AD) Plaggic Anthrosol yielded some interesting
features: a. The biomarker spectra of the 2Ap horizons (agricultural layer below
the plaggic deposits) are dominated by biomarkers of deciduous trees (dominated
by Quercus), indicating the use of organic litter from the forests. These trees are
also present in the pollen spectra. b. The biomarker spectra of the plaggic deposits
are dominated by crop species (Avena, Secale, Fagpyrum), Calluna is absent in
most of the spectra. This is different from pollen spectra where Calluna is present,
together with crop species and transported pollen of other species. Only the biomarker
spectra of the upper 10 cm of the plaggic horizons are dominated by Calluna. c.
Comparison of the spectra of the buried and regular Plaggic Anthrosols show the
contribution of biomarkers of roots of Zea mais (introduced around 1950 AD),
suppressing the other species. The negligible percentages of Calluna in biomarker
spectra of plaggic deposits suggest an overestimating of the use of heath sods in
the traditional interpretation of the genesis of plaggic horizons, the dominance of
crop species in biomarker spectra of plaggic deposits suggests underestimating of
the use of straw as source material for the production of organic stable manure to
fertilize ancient arable fields. While the results of biomarker analyses seem to indicate
compelling new insights in the practices of plaggen agriculture in The Netherlands,
we wish to stress that the biomarker method using VERHIB is still in the early
stages of its development and some care must be taken with the interpretation of the
results.
References: 1. van Mourik, J.M., Slotboom, R.T., Wallinga, J., 2011. Chronology of
plaggic deposits; palynology, radiocarbon and optically stimulated luminescence dating of
the Posteles (NE-Netherlands). Catena 84, 54-60. 2. Van Mourik, J.M., Seijmonsbergen,
A.C., Slotboom, R.T. and Wallinga, J, (2011a). The impact of human land use on soils and
landforms in cultural landscapes on aeolian sandy substrates (Maashorst, SE Netherlands).
Quaternary International 265 (2012) 74-89. |
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