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| Titel |
Influence of management practices on C stabilization pathways in agricultural volcanic ash soils (Canary Islands, Spain) |
| VerfasserIn |
Zulimar Hernandez, Ana Maria Alvarez, Pilar Carral, Tomás de Figueiredo, Gonzalo Almendros |
| 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 |
250098591
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| Publikation (Nr.) |
 EGU/EGU2014-14282.pdf |
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| Zusammenfassung |
| Although C stabilization mechanisms in agricultural soils are still controversial [1], a series
of overlapped pathways has been suggested [2] such as: i) insolubilization of low molecular
weight precursors of soil organic matter (SOM) with reactive minerals through physical and
chemical bonding, ii) selective accumulation of biosynthetic substances which are recalcitrant
because of its inherent chemical composition, and iii) preservation and furter diagenetic
transformation of particulate SOM entrapped within resistant microaggregates, where
diffusion of soil enzymes is largely hampered. In some environments where carbohydrate and
N compounds are not readily biodegraded, e.g., with water saturated micropores, an
ill-known C stabilization pathway may involve the formation of Maillard’s reaction
products [3]. In all cases, these pathways converge in the formation of recalcitrant
macromolecular substances, sharing several properties with the humic acid (HA) fraction
[4].
In template forests, the selective preservation and further microbial reworking of plant
biomass has been identified as a prevailing mechanism in the accumulation of recalcitrant
SOM forms [5]. However, in volcanic ash soils with intense organomineral interactions,
condensation reactions of low molecular weight precursors with short-range minerals may be
the main mechanism [6].
In order to shed some light about the effect of agricultural management on soil C
stabilization processes on volcanic ash soils, the chemical composition of HA and some
structural proxies of SOM informing on its origin and potential resistance to biodegradation,
were examined in 30 soils from Canary Islands (Spain) by visible, infrared (IR) and 13C
nuclear magnetic resonance (NMR) spectroscopies, elementary analysis and pyrolytic
techniques.
The results of multivariate treatments, suggested at least three simultaneous C
stabilization biogeochemical trends: i) diagenetic alteration of plant biomacromolecules in
soils receiving periodical inputs of manures. This includes accumulation of slightly
transformed material in scenarios of high C mineralization rates, such are in vitrandic soils.
ii) Accumulation of resilient organo-mineral complexes in non andic-soils with crystalline
minerals and probable inputs of pyrogenic C in the past. Finally, iii) accumulation of aliphatic
structures, such as carbohydrate- and N-rich macromolecules, leading to HAs with
characteristics in common with those formed in aquatic environments. The formation of these
HAs could be favoured by microbial activity in andic Anthrosols, and would define a specific
type of soil C stabilization mechanism of aliphatic compounds encapsulated in
nanoparticle-size soil pores, where persistent hydromorphic conditions were favoured by
amorphous gels in volcanic ash soils.
[1] Lal, R., 2004. Mitigation and Adaptation Strategies for Global Change 12,
303–322.
[2] Stevenson, F.J., 1994. Humus Chemistry: Genesis, composition, reactions. 2nd ed.
Wiley, New York.
[3] Ellis, G.P., 1959. Advances in Carbohydrate Chemistry 14, 63–134.
[4] Almendros, G., 2008. Humic substances. In: Cheswort, W. (Ed.), Encyclopedia of Soil
Science, Springer, Dordretch, pp. 97–99.
[5] Kögel-Knabner, I., Hatcher, P.G., Tegelaar, E.W., de Leeuw J.W., 1992. The Science
of the Total Environment 113, 89–105.
[6] Hernández, Z., Almendros, G., Carral, P., Álvarez, A., Knicker, H., Pérez-Trujillo, J.P.,
2012. European Journal of Soil Science 63, 603–615. |
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