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Titel |
The fate of P solubilization during decomposition of soil organic matter as regulated by drying-rewetting and freeze – thawing events |
VerfasserIn |
Ilya Yevdokimov, Evgenia Blagodatskaya |
Konferenz |
EGU General Assembly 2015
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 17 (2015) |
Datensatznummer |
250106845
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Publikation (Nr.) |
EGU/EGU2015-15061.pdf |
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Zusammenfassung |
Drying-rewetting and freeze-thawing events are known to provoke solubilization of nutrients in soil. However, immobilization-mineralization cycles of such an important nutrient as phosphorus under these abiotic perturbations are still poorly understandable, mainly because the P pulses are often disguised by fast processes of P sorption on soil particles. Our research aimed to elucidate the P release and its uptake by soil microorganisms depending on drying-rewetting and freeze-thawing events.
The effect of abiotic factors was studied in incubation experiments with soil sampled from four soil types: Podzol (Corg 3.3%, pHH2O 3.5), Phaeozem (Corg 1.4%, pHH2O 5.6), Chernozem (Corg 3.4%, pHH2O 6.9), and Calcisol (Corg 1.9%, pHH2O 8.3). Three treatments were used: control (soil incubated at 22oC and 70% WHC), drying-rewetting (DRW) and freeze-thawing (FTH). Air-drying in DRW treatment was provided at 22oC temperature during 12 h, followed by 6 d exposition at this temperature, rewetting to 70% WHC and measuring water-extractable and microbial P pools 12 h after rewetting. Soil in FTH treatment was exposed to freezing at -10oC, 6 d exposition at the same temperature and 12 h thawing at 4oC followed by the same analytical procedures as for DRW treatment. Microbial and water extractable P pools were analyzed in control soil in parallel with those in DRW and FTH. Soil in all the treatments was labeled with a spike of 33P- orthophosphate. Microbial P was determined using the “direct” fumigation-extraction where 24 h exposition of soil to chloroform vapors was substituted by direct water/chloroform extraction; both water extractable and microbial P were analyzed after sorption on anion-exchange membranes.
Despite the variability of soil pH and Corg content, all the soil types tested demonstrated similar trends: freeze-thawing led to increase in water extractable 33P, while soil in DRW treatments had lower 33P values compare to control. Microbial 33P followed the pattern FTH
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