Unlocking soil health: carbon determination in agricultural soils

By accurately measuring organic carbon, the method helps farmers and soil scientists understand soil health, fertility, and the carbon sequestration potential of the soil. It is an essential tool in developing sustainable agricultural practices, such as managing organic amendments and crop rotations, to improve soil quality and mitigate soil degradation.
The cost-effective Black-Walkley method is a widely used and effective technique for determining organic carbon in agricultural soils. While it mainly targets organic carbon, it provides critical insights into soil health, helping distinguish the biological contributions of carbon. When used in conjunction with other mineralogical techniques, it can help identify the role of lithogenic (inorganic) carbon sources and further enhance soil health assessments.
The method helps to isolate and focus on organic carbon, but when combined with mineralogical analyses (such as clay content or other geological markers), it can contribute to a clearer understanding of how much of the soil's carbon comes from biological processes and how much is influenced by the underlying lithogenic or mineral sources.
If the soil contains a significant amount of lithogenic minerals, such as carbonates from parent rock, these can impact the overall carbon content. However, the Black-Walkley method primarily targets the organic fraction, and the effect of lithogenic sources would need to be accounted for separately in some cases. This method helps quantify the organic carbon in the soil, which is a key indicator of soil fertility and microbial activity. Organic carbon is a critical component for improving soil structure, water retention, and nutrient availability, all of which affect soil health. The Black-Walkley method does not directly measure lithogenic carbon (inorganic carbon from parent rock), but it is useful for estimating the organic fraction of carbon in the soil, which is influenced by both biological processes and geological sources.
Soil samples were collected from the Ovce pole region, (eastern part of the territory of North Macedonia), including the landfill with the carbon farming practice (pilot site) as well. The method validation was improved with QA protocol in accordance with the ISO/IEC 17025:2017. Accuracy, precision, LOD, LOQ, reproductivity, reputability, measurement uncertainty and working range were included for the quality insurance of the method. The data normalization has been introduced using log-normal transformation, for excluding the outliers. Data matrix has been improved with bivariate statistics of correlation matrix and multivariate extraction of dominant variables.