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Quantification of deep soil carbon by a wet digestion technique

Sangmanee, P., Dell, B., Harper, R.J.ORCID: 0000-0003-0268-2917 and Henry, D.J.ORCID: 0000-0002-9629-4423 (2017) Quantification of deep soil carbon by a wet digestion technique. Soil Research, 55 (1). pp. 78-85.

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Two wet digestion methods were evaluated using pure kaolinite as background for quantifying small concentrations of carbon (<0.05% total organic carbon (TOC)) in deep kaolinitic regolith in south-Western Australia. The limit of detection and limit of quantification of the Walkley-Black method (0.015 and 0.050% TOC respectively) were approximately five times lower than those of the Heanes method (0.085 and 0.281% TOC respectively). Both methods showed excellent linearity (R2>0.99) using prepared standards (lignin, humic acid, cellulose and chitin mixed with kaolinite and their combinations), in the concentration range 0.008-1.000% TOC. However, the percentage carbon recovery values were underestimated for chitin. The Walkley-Black method (TOCWB, %) was evaluated with 94 calibration and 27 validation deep soil samples (1-35m soil depth) and compared with a dry combustion (Elementar) technique (TOCactual, %). The predictive equation (TOCactual≤1.66TOCWB+0.018) (R2≤0.91) obtained from the calibration set agreed well with the benchmark dry combustion values (root mean square error≤0.017) and is recommended for quantification of deep soil carbon in other kaolinitic regoliths.

Item Type: Journal Article
Murdoch Affiliation(s): School of Veterinary and Life Sciences
Publisher: CSIRO
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