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| Titel |
Patterns of soil carbon and nitrogen in relation to soil movement under different land uses in mountain farmland fields (South Central Pyrenees) |
| VerfasserIn |
A. Navas, L. Gaspar, M. López-Vicente, J. Machín |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250025619
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| Zusammenfassung |
| Cultivation on mountain landscapes has been identified as a main factor triggering soil
erosion. The loss of soil particles and its redistribution across the landscape is associated to
that of soil nutrients. Patterns of soil erosion and of the transport and redistribution of soil
particles appear to be closely linked to that of carbon in soils. In this work the redistribution
of total organic carbon and nitrogen and that of soil particles is analysed in different
geomorphic parts of mountain farmland fields. A southern orientated hillslope in the
Central Spanish Pyrenees was selected as representative of main land uses. In the
region, farmland abandonment during the last decades affects 74 % of its surface
and therefore patterns of soil and nutrient losses in the fields are affected by land
abandonments and tillage. A set of cultivated and abandoned fields with different ages of
land abandonment, slope gradients and length were selected to conduct this study.
In each of the fields, sampling was carried out in different parts of the slope to
assess the pattern of particle size distribution and of total organic carbon (TOC) and
total nitrogen (TN). Other general soil properties analysed: pH, EC and carbonate
contents provided supplementary information for better understanding soil and
nutrient redistribution patterns. In addition, information provided by a previous
research using fallout caesium 137 was used to document soil movement in these
fields. At the bottom slope of the fields significant increases in the sand percentage
occurs whereas the clay contents decrease slightly. This could be due to the export of
the finest fractions with high runoff in spite that fields are surrounded with stone
walls as well as to some clay leaching in the soil profile, as suggested by the lowest
values of EC at the bottom of the slope. The results indicate that in general TOC
increases from the crest to the bottom slope of the fields. Percentages of TOC increases
range from 5 to 35 %. In spite that some soil carbon could have been exported with
the clay fraction, also carbon mineralization may have occurred. Although TOC
decreases are less common they also occurred when there is no evidence of soil
deposition at the bottom of the slope therefore, TOC loss is associated to lost of soil
particles. In parallel with TOC increases significant increases of TN are also registered
in most fields. Therefore, soil deposition at the bottom slope as indicated by the
137Cs inventories is generally paralleled with increases in TOC and TN contents. |
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