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Base cations in the soil bank: non-exchangeable pools may sustain centuries of net loss to forestry and leaching


Title (Dublin Core)

Base cations in the soil bank: non-exchangeable pools may sustain centuries of net loss to forestry and leaching

Description (Dublin Core)

<p>Accurately quantifying soil base cation pool sizes is
essential to interpreting the sustainability of forest harvests from element
mass-balance studies. The soil-exchangeable pool is classically viewed as
the bank of “available” base cations in the soil, withdrawn upon by plant
uptake and leaching and refilled by litter decomposition, atmospheric
deposition and mineral weathering. The operational definition of this soil
bank as the exchangeable (salt-extractable) pools ignores the potential role
of “other” soil nutrient pools, including microbial biomass, clay
interlayer absorbed elements, and calcium oxalate. These pools can be large
relative to “exchangeable” pools. Thus neglecting these other pools in
studies examining the sustainability of biomass extractions, or need for
nutrient return, limits our ability to gauge the threat or risk of
unsustainable biomass removals. We examine a set of chemical extraction data
from a mature Norway spruce forest in central Sweden and compare this
dataset to ecosystem flux data gathered from the site in previous research.
The 0.2&thinsp;M HCl extraction released large pools of Ca, K, Mg, and Na,
considerably larger than the exchangeable pools. Where net losses of base
cations are predicted from biomass harvest, exchangeable pools may not be
sufficient to support more than a single 65-year forest rotation, but
acid-extractable pools are sufficient to support many rotations of
net-ecosystem losses. We examine elemental ratios, soil clay and carbon
contents, and pool depth trends to identify the likely origin
of the HCl-extractable pool. No single candidate compound class emerges, as very strongly supported by the data, as being the major constituent of the HCl-extractable fraction. A combination of microbial biomass, fine
grain, potentially shielded, easily weatherable minerals, and non-structural
clay interlayer bound potassium may explain the size and distribution of the
acid-extractable base cation pool. Sequential extraction techniques and
isotope-exchange measurements should be further developed and, if possible,
complemented with spectroscopic techniques to illuminate the identity of and
flux rates through these important, and commonly overlooked, nutrient pools.</p>

Creator (Dublin Core)

N. P. Rosenstock
J. Stendahl
G. van der Heijden
L. Lundin
E. McGivney
K. Bishop
S. Löfgren

Subject (Dublin Core)

Environmental sciences

Publisher (Dublin Core)

Copernicus Publications

Date (Dublin Core)


Type (Dublin Core)


Identifier (Dublin Core)


Source (Dublin Core)

SOIL, Vol 5, Pp 351-366 (2019)

Language (Dublin Core)


Relation (Dublin Core)

Provenance (Dublin Core)

Journal Licence: CC BY