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| Titel |
Seasonal dynamics of CO2 efflux in soils amended with composted and thermally-dried sludge as affected by soil tillage systems in a semi-arid agroecosystem |
| VerfasserIn |
Juan Carlos García-Gil, Pedro Soler-Rovira, Esther G. López-de-Sá, Alfredo Polo |
| 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 |
250098111
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| Publikation (Nr.) |
 EGU/EGU2014-13753.pdf |
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| Zusammenfassung |
| In semi-arid agricultural soils, seasonal dynamic of soil CO2 efflux (SCE) is highly variable.
Based on soil respiration measurements the effects of different management systems
(moldboard plowing, chisel and no-tillage) and the application of composted sludge (CS) and
thermally-dried sewage sludge (TSS) was investigated in a long-term field experiment (28
years) conducted on a sandy-loam soil at the experimental station “La Higueruela” (40o
03’N, 4o 24’W). Both organic amendments were applied at a rate of 30 Mg ha-1 prior to
tillage practices. Unamended soils were used as control for each tillage system. SCE was
moderate in late spring (2.2-11.8 μmol CO2 m-2 s-1) when amendments were applied and
tillage was performed, markedly decreased in summer (0.4-3.2 μmol CO2 m-2 s-1),
following a moderate increase in autumn (3.4-14.1 μmol CO2 m-2 s-1), rising sharply in
October (5.6-39.8 μmol CO2 m-2 s-1 ). In winter, SCE was low (0.6-6.5 μmol CO2
m-2 s-1). In general, SCE was greater in chisel and moldboard tilled soils, and in
CS and particularly TSS-amended soils, due to the addition of labile C with these
amendments, meanwhile no-tillage soils exhibited smaller increases in C efflux
throughout the seasons. Soil temperature controlled the seasonal variations of SCE. In
summer, when drought occurs, a general decrease of SCE was observed due to a
deficit in soil water content. After drought period SCE jumped to high values in
response to rain events (“Birch effect”) that changed soil moisture conditions. Soil
drying in summer and rewetting in autumn may promotes some changes on the
structure of soil microbial community, affecting associated metabolic processes, and
enhancing a rapid mineralization of water-soluble organic C compounds and/or
dead microbial biomass that acts as an energy source for soil microorganisms. To
assess the effects of tillage and amendments on SCE, Q10 values were calculated.
Data were grouped into three groups according to soil moisture (0.03-0.10 m3m-3,
0-11-0.21 m3m-3, 0.22-0.30 m3m-3). In general, Q10 values were lower at elevated
temperatures when soil moisture contents decreased, confirming that SCE is less
sensitive to soil temperature during drought periods. Q10 values were higher in
moldboard and chisel tilled soils, possibly due to the incorporation of residues
into soil and the increase of soil C substrate, meanwhile in no-tillage part of the
organic C pools are likely protected from microorganisms by physico-chemical
mechanisms. TSS-amended soils exhibited higher Q10 values than CS, pointing that the
biochemical lability of the organic C added with amendments exerts an influence on
SCE.
Acknowledgements: this research was supported by the Spanish CICYT, Project no.
CTM2011-25557. |
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