Journal: Frontiers in Soil Science

Abbreviation

Front. Soil Sci.

Publisher

Frontiers Media

Journal Volumes

ISSN

2673-8619

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2021 - 20232
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Publications 1 - 2 of 2
  • Tracing 33P-labelled organic phosphorus compounds in two soils: New insights into decomposition dynamics and direct use by microbes
    Item type: Journal Article
    Wasner, Daniel; Prommer, Judith; Zezula, David; et al. (2023)
    Frontiers in Soil Science
    Introduction: Organic phosphorus (Po) compounds constitute an important pool in soil P cycling, but their decomposition dynamics are poorly understood. Further, it has never been directly tested whether low molecular weight Po compounds are taken up by soil microbes in an intact form, which reduces the dependence of their P acquisition on extracellular phosphatases. Methods: We investigated the short-term fate (24 h) of five 33P-labelled Po compounds (teichoic acids, phospholipids, DNA, RNA and soluble organophosphates) and 33P-labelled inorganic P (Pi) in two soils. Results: We found indications that soil microbial breakdown of phosphodiesters was limited by the depolymerization step, and that direct microbial uptake of Po occurred to a substantial extent. Discussion: We postulate a trade-off between direct Po uptake and complete extracellular Po mineralization. These findings have profound consequences for our understanding of microbial P cycling in soils.
  • Soil Phosphorus Exchange as Affected by Drying-Rewetting of Three Soils From a Hawaiian Climatic Gradient
    Item type: Journal Article
    Helfenstein, Julian; Frossard, Emmanuel; Pistocchi, Chiara; et al. (2021)
    Frontiers in Soil Science
    Current understanding of phosphorus (P) dynamics is mostly based on experiments carried out under steady-state conditions. However, drying-rewetting is an inherent feature of soil behavior, and as such also impacts P cycling. While several studies have looked at net changes in P pool sizes with drying-rewetting, few studies have dynamically tracked P exchange using isotopes, which would give insights on P mean residence times in a given pool, and thus P availability. Here, we subjected three soils from a climatic gradient on the Kohala peninsula from Hawaii to 5-month drying-rewetting treatments. The hypotheses were that physico-chemical and biotic processes would be differently affected by repeated drying-rewetting cycles, and that response would depend on climatic history of the soils. Soils were labeled with 33P and 18O enriched water. At select time intervals, we carried out a sequential extraction and measured P concentration, 33P recovery (only first 3 months), and incorporation of 18O from water into phosphate. This allowed tracing P dynamics in sequentially extracted pools as well as O dynamics in phosphate, which are driven by biological processes. Results showed that P concentration and 33P recovery were predominantly driven by soil type. However, across all soils we observed faster dilution of 33P from resin-P into less mobile inorganic pools under drying-rewetting. On the other hand, O dynamics in phosphate were mostly governed by drying-rewetting treatment. Under drying-rewetting, considerably less O was incorporated from water into phosphate of resin-P, microbial-P and HCl-P, suggesting that drying-rewetting reduced biological P cycling. Hence, our results suggest that repeated drying-rewetting increases inorganic P exchange while reducing biological P cycling due to reduced microbial activity, independent of climatic history of the soils. This needs to be considered in P management in ecosystems as well as model representations of the terrestrial P cycle.
Publications 1 - 2 of 2