Soil P availability along a catena located at the Sierra de Gata Mountains, Western Central Spain
2008
Turrión, María-Belén | Schneider, Knut | Gallardo, Juan F.
The main objective of this study was to know the soil P availability in Quercus pyrenaica (deciduous oak) forests at the “Sierra de Gata” Mountains (Central Western Spain) and determine the factors controlling the availability of P in these soils. Twelve different oak stands along a rainfall gradient were selected, differentiating underlying geological materials: granites and schist-greywackes. Samples from selected soil horizons were taken and the available soil P was determined using an anion exchange membrane (P AEM). P retention capacity (P RC) was used as a rapid measure of soil P adsorption. P mineralization rate and acid phosphatase activity (APA) were determined in samples of the epipedons. Sites developed over schist-greywacke materials showed significantly lower contents of P AEM than sites over granites. Soil P RC was related positively to the contents of organically complexed Al+Fe and negatively to P AEM contents, confirming that metal-organic complexes play an important role in the solubility and availability of soil P. The APA did not show any direct relationship neither with the net P mineralization rate nor with P AEM, but did with the soil organic carbon (SOC) content. P mineralization did not only depend on the biochemical mineralization, but also on the biological mineralization of SOC by heterotrophic micro-organisms, which activity is favoured by the SOC content.
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