Kogut B. M., Milanovsky E. Yu., Khamatnurov Sh. A. On methods for determining the organic carbon content in soils (a critical review)// Bulletin of the Soil Institute named after V. V. Dokuchaev. 2023;(114):5–28. https://doi.org/10.19047/0136-1694-2023-114-5-28
Abstract. The article outlines the theoretical foundations of methods for determining the content of soil organic carbon (SOC) by the direct method of dry combustion using automatic analyzers and indirect method of oxidability according to Tyurin and Walkley-Black. It provides the authors’ own and literature experimental analysis data on various soils using these methods. A comparative analysis of said data showed that, in some cases, the SOC value determined by oxidability is lower than that obtained by dry combustion (in the majority of cases), while in other cases it is higher. This conclusion is fully consistent with Tyurin’s theoretical stance on the chemical nature of soil organic matter (SOM). The study offers a schematic description of the process of identifying the content of total (organic) carbon in non-carbonate soils by the method of dry combustion using automatic analyzers Leco (USA) and AN-7529 (Gomel, Belarus). It points out the challenges of determining the SOC content by the method of dry combustion using automatic analyzers in carbonate soils. The authors recommend to determine the content of inorganic carbon by decomposing carbonates with a HClO4 solution using an AN-7529 express analyzer for these soils. The metrological feature of the direct method of determining the SOC content is better than that of the indirect one, which acts as convincing evidence of the opinions of Schollenberg and Tyurin about the approximate nature of the latter. The article concludes that the indicators determined by the methods of Tyurin and Walkley-Black as well as the method of dry combustion are chemically independent, and they characterize the oxidability and organic carbon content of the POC, respectively. It is recommended that the method of dry combustion is used with automatic analyzers when monitoring the content and stocks of organic carbon in soils.