Article Cite This: ACS Earth Space Chem. XXXX, XXX, XXX−XXX
Measuring Plant-Available Mg, Ca, and K Pools in the SoilAn Isotopic Dilution Assay Gregory van der Heijden,*,† Jérémie Bel,† Carol-Ann Craig,‡ Andrew J. Midwood,‡,⊥ Louis Mareschal,§ Jacques Ranger,† Etienne Dambrine,∥ and Arnaud Legout† †
INRA UR 1138 Biogéochimie des Ecosystèmes Forestiers, FR-54280 Champenoux, France The James Hutton Institute, Aberdeen AB15 8QH, United Kingdom § CIRAD UMR Eco&Sol, FR-64060 Montpellier, France ∥ INRA − UMR 042 CARRTEL, Université de Savoie, FR-73376 Le Bourget-du-Lac Cedex, France ‡
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ABSTRACT: In many forest ecosystems, plant-available pools of Mg, Ca, and K are assumed to be stored in the soil as exchangeable cations adsorbed on the cation exchange complex (exchangeable pools). However, between soil minerals and exchangeable cations exists a gradient of Mg, Ca, and K storage forms that have not been fully characterized and may play an important role in plant nutrition and biogeochemical cycles. We hypothesize that sources of Mg, Ca, and K in the soil other than the conventionally measured exchangeable pools are plant-available on very short time scales (
