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| Titel |
Irrigation-induced changes in soil organic matter dynamics and soil aggregation in semiarid Mediterranean agrosystems |
| VerfasserIn |
Marcos Apesteguia, Luis Orcaray, Alain Plante, Iñigo Virto |
| 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 |
250094075
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| Publikation (Nr.) |
 EGU/EGU2014-9413.pdf |
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| Zusammenfassung |
| Soil organic matter dynamics are of special importance for the sustainability of agrosystems,
due to their role in soil quality, soil fertility and atmospheric C sequestration. Irrigation is
known to influence organic matter dynamics, but this influence is not completely understood
and may vary among different environmental conditions and crop and soil managements. An
experimental field was set up in a Calcic Haploxereptin Navarra, NE Spain with the aim of
evaluating the consequences of the transformation from dryland to irrigation in agricultural
carbonated soils in semiarid conditions. The experimental field included four treatments:
rainfed wheat (W-rf), irrigated wheat (W-irr), rainfed maize (M-rf) and irrigated maize
(M-irr). The quantity of the crop biomass potentially added to the soil (non-harvested
crops biomass) was measured during the two first growing seasons. Organic C
storage, aggregation and organic C distribution among aggregate size-classes, and
the proportion of maize-derived C incorporated from crop residues in M-rf and
M-irr were measured on topsoil (0-10 cm) samples from year 0 (baseline) and two
years after the initiation of the experiment. No differences were observed in the
cumulative non-harvested biomass produced in the two years in M-irr and W-irr in
comparison to rainfed treatments (M-rf and W-rf). No increase in total organic C
stocks or distribution among aggregate classes among treatments was observed
either. However, evidence of a change in organic matter dynamics in the soil under
irrigation was found from 13C data, which were used to estimate the proportion of
maize-derived C in M-irr and M-rf. This proportion was notably higher in M-irr than
M-rf, both in terms of total soil organic C from maize in the soil (13.4 ± 0.7% and
4.9 ± 1.4%, respectively), and in relation to the proportion of the non-harvested
maize biomass incorporated to the soil in each treatment (up to 34 ± 3 % in M-irr
for only 16±4 % in M-rf). The incorporation of organic C from maize occurred
preferentially in larger aggregates (2-4 mm) in both treatments. A transfer from large
aggregates to medium and smaller aggregates (0.25-2 mm and 0.05-0.25 mm) was
observed only in M-irr, supporting the hypothesis that irrigation adoption changed the
pace of the incorporation of fresh organic matter into aggregates. These results
indicate that converting from dryland to irrigated cropland can have significant
effects in organic matter dynamics in the short-term in semi-arid Mediterranean soils. |
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