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| Titel |
Physico-chemical changes in dissolved organic matters in the rhizosphere of plants grown in soil amended with organic wastes: an in-situ investigation. |
| VerfasserIn |
Tanalou Djae, Matthieu Bravin, Cédric Garnier, Jean-Fabien Mayen, Emmanuel Doelsch |
| 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 |
250093473
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| Publikation (Nr.) |
 EGU/EGU2014-8217.pdf |
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| Zusammenfassung |
| In agricultural context, prerequisite condition to forecast trace metal phytodisponibility is to
evaluate trace metal speciation in the rhizosphere solution, especially in soil amended with
organic wastes. The most advanced trace metal speciation models (e.g. WHAM,
NICA-DONNAN) take into account dissolved organic matter (DOM) reactivity toward trace
metals. Generally, the scientific community uses, a fixed percentage of DOM reactivity,
usually of 40 % to 80 %, to predict trace metal speciation. However, recent studies have
demonstrated that the binding capacity of DOM towards trace metals is much larger
than expected. The aim of our study was to investigate the mechanisms supporting
the variability in DOM reactivity by assessing the physico-chemical changes of
DOM in the bulk-soil and rhizosphere in context of agricultural recycling of organic
wastes.
An in-situ experiment was conducted in Reunion Island (Indian Ocean). Two plant
species, i.e. a graminaceous species the fescue (Festuca rubra) and a dicotyledonous species
the tomato (Lycopersicon esculentum), were grown on a soil where we applied two types of
organic wastes (pig manure compost and poultry manure compost) at three rates and a
mineral fertilizer. Following this experiment, the soil either adhering to the roots (i.e.
rhizosphere) or not (i.e. bulk-soil) was sampled and the soil solution was recovered by
chemical extraction. DOM concentration, total acidity and DOM fluorescence were
measured.
Root activities and organic wastes induced variations in the physico-chemical parameters
of DOM. DOM concentration tended to increase in bulk-soil with increasing organic waste
application rate. DOM concentrations measured in rhizosphere are significantly greater than
those in the bulk-soil especially when organic wastes were applied to soil. Preliminary results
allow us to observe a decrease in the density of carboxylic-like (pKa |
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