Abstract
The objective of this study was to compare the results of calcimetric and dry combustion methods for quantitative estimation of soil total inorganic carbon (TIC). To this aim, 117 soil samples from three localities in the Mediterranean area (one in Spain and two in Southern Italy), representing a wide range of total inorganic carbon contents (ranging from 1.9 to 54 g 100 g−1), were collected. TIC (expressed as CaCO3) was quantified using the volumetric calcimeter method, as reference, and dry combustion in order to find an accurate and rapid method, suitable for different types of soils. The results revealed a concordance between the two methods compared, as shown by the recovery values close to one, for the whole data set and for data grouped per experimental site. Specifically, the dry combustion method showed slightly greater values of TIC compared to volumetric method, probably due to soil acid pretreatments, in dry combustion, and to an incomplete decomposition of carbonates that would require more time for removal, in a calcimeter method. Linear regression equations between the two methods were not affected by different soil types. Overall, our study demonstrated that the dry combustion was a reliable method and could provide accurate estimates of TIC in soils with different calcium carbonate content.
Highlights
Murcia soil can be classified as a calcareous soil, due to high levels of calcium carbonate (CaCO3, 54 g 100 g−1 ), whereas the Sarno site was characterized by a low carbonate content and Fasano showed intermediate values
The discrepancies in the results observed in the total inorganic carbon (TIC)–total organic carbon content (TOC) relationship can be attributed to many factors, including soil properties, climate conditions, and land management practices, which affect the processes of precipitation and dissolution of carbonate, soil organic matter mineralization, etc. [28,29,33]
By comparing of volumetric calcimeter method, which is considered the standard analytical method for soil inorganic carbon quantification, and dry combustion, it emerged that the latter method could provide an accurate estimate of total inorganic carbon in soils with a wide range of calcium carbonate contents
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Licensee MDPI, Basel, Switzerland.Attribution (CC BY) license (https://creativecommons.org/licenses/by/ 4.0/).Soil carbon storage, as the third largest carbon pool in the Earth System, plays an important role in the global carbon cycle and climate change [1]. In world soils, most of carbon (C) is present as organic C (OC) in the form of more or less complex and stable organic compounds originating from plant, animal, and microbial residues. The inorganic
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