In:
SOIL, Copernicus GmbH, Vol. 8, No. 1 ( 2022-01-12), p. 1-15
Abstract:
Abstract. At the early stages of pedogenesis, the dynamics of phosphorus (P)
in soils are controlled by microbial communities, the physicochemical
properties of the soil and the environmental conditions. While various
microorganisms involved in carrying out biogeochemical processes have been
identified, little is known about the actual contribution of microbial
processes, such as organic P hydrolysis and microbial P turnover, to P
cycling. We thus focused on processes driven by microbes and how they affect
the size and cycling of organic and inorganic soil P pools along a soil
chronosequence in the Chamser Kangri glacier forefield (Western Himalayas).
The rapid retreat of the glacier allowed us to study the early stages of
soil formation under a cold arid climate. Biological P transformations were
studied with the help of the isotopic composition of oxygen (O) in phosphate
(δ18OP) coupled to sequential P fractionation performed on
soil samples (0–5 cm depth) from four sites of different age spanning 0 to
100–150 years. The P bound to Ca, i.e., 1 M HCl-extractable P,
still represented 95 % of the total P stock after approximately 100 years of soil
development. Its isotopic composition was similar to the parent material at
the most developed site. Primary phosphate minerals, possibly apatite,
mostly comprised this pool. The δ18OP of the available P
and the NaOH-extractable inorganic P instead differed from that of the
parent material, suggesting that these pools underwent biological turnover.
The δ18OP of the available P was mostly controlled by the
microbial P, suggesting fast exchanges occurred between these two pools
possibly fostered by repeated freezing–thawing and drying–rewetting cycles.
The release of P from organic P becomes increasingly important with soil
age, constituting one-third of the P flux to available P at the oldest site.
Accordingly, the lighter isotopic composition of the P bound to Fe and Al
oxides at the oldest site indicated that this pool contained phosphate
released by organic P mineralization. Compared to previous studies on early
pedogenesis under alpine or cold climate, our findings suggest a much slower
decrease of the P-bearing primary minerals during the first 100 years of
soil development under extreme conditions. However, they provide evidence
that, by driving short-term P dynamics, microbes play an important role in
controlling the redistribution of primary P into inorganic and organic soil
P pools.
Type of Medium:
Online Resource
ISSN:
2199-398X
DOI:
10.5194/soil-8-1-2022
DOI:
10.5194/soil-8-1-2022-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2022
detail.hit.zdb_id:
2834892-8
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