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| Titel |
Processes controlling soil P amounts and availability along a weathering gradient |
| VerfasserIn |
Julian Helfenstein, Federica Tamburini, Christian von Sperber, Michael Massey, Chiara Pistocchi, Oliver Chadwick, Peter Vitousek, Emmanuel Frossard |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250152555
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| Publikation (Nr.) |
 EGU/EGU2017-17405.pdf |
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| Zusammenfassung |
| In 1976 Walker and Syers presented a model describing the development of P pools with
increasing weathering status of a soil (Walker and Syers 1976). This model has been
repeatedly confirmed along gradients of different soil ages as well as gradients of different
climatic conditions (Crews et al. 1995, Tamburini et al. 2012, Roberts et al. 2015, Feng et
al. 2016). However, limited information is available on the processes controlling
P amounts and availability along a weathering gradient. We used isotopic (33P,
18O), spectroscopic (P K-edge XANES), and other (enzymatic activity, chemical P
speciation) methods to reveal drivers of P dynamics along the 150’000-year-old Kohala
lava flow on Hawai’i, which stretches from 250 mm to over 3000 of mean annual
precipitation. Chemical extractions and X-ray absorption spectroscopy show the gradual
disappearance of apatite in favor of Fe- and Al-sorbed P species as well as organic
P.
We then distinguish two different types of processes: 1) processes determining the total
amount of P in the topsoil, and 2) processes determining P availability. While weathering of
apatite and eolian erosion control P amounts on less weathered and arid soils, leaching and
biological uplift become increasingly important with increasing soil weathering status. On
very weathered sites, leaching becomes the dominant process controlling P amounts, though
it is partially counteracted by biological uptake and atmospheric dust deposition. In
terms of P availability, dissolution of mineral P adds to the available P pool up to
the intermediate range. Activity of acid phosphatase suggests that mineralization
becomes increasingly important with higher weathering of soils. Despite this, P
availability decreases drastically, as a result of continued loss of highly-mobile P
through immobilization by biomass, increased P-sorption capacity by soils, and
leaching.
Crews, T. E., K. Kitayama, J. H. Fownes, R. H. Riley, A. Darrell, D. Mueller-dombois, and P.
M. Vitousek. 1995. Changes in Soil Phosphorus Fractions and Ecosystem Dynamics across a
Long Chronosequence in Hawaii. Ecology 76:1407-1424.
Feng, J., B. L. Turner, X. Lü, Z. Chen, K. Wei, J. Tian, C. Wang, W. Luo, and L. Chen. 2016.
Phosphorus transformations along a large-scale climosequence in arid and semiarid
grasslands of northern China. Global Biogeochemical Cycles 30.
Roberts, K., D. Defforey, B. L. Turner, L. M. Condron, S. Peek, S. Silva, C. Kendall,
and A. Paytan. 2015. Oxygen isotopes of phosphate and soil phosphorus cycling
across a 6500 year chronosequence under lowland temperate rainforest. Geoderma
257-258:14-21.
Tamburini, F., V. Pfahler, E. K. Bünemann, K. Guelland, S. M. Bernasconi, and E. Frossard.
2012. Oxygen isotopes unravel the role of microorganisms in phosphate cycling in soils.
Environmental Science and Technology 46:5956-5962.
Walker, T. W., and J. K. Syers. 1976. The fate of phosphorus during pedogenesis. Geoderma
15:1-19. |
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