The study of the organic carbon in the regional agricultural soils is of fundamental importance to evaluate the soil fertility as well as minimizing the release of greenhouse gases to the atmosphere. The analytical approach of the soli TOC^® cube allows the discrimination of inorganic and organic compounds but avoids complex and tedious pre-treating of the samples with hazardous chemicals and has the capacity to separate and measure organic compounds with different thermal behaviours (thermally labile, namely TOC400 and thermally recalcitrant, namely ROC) besides the total inorganic carbon (TIC) in one single analytical run. The suitable analytical approach for the differentiation of carbon fractions has been developed with the assistance of Elementar using a new instrument, the soli TOC^® cube.