The steppe and steppic regions in Eurasia are extensively covered by loess materials, from which Chernozems and Kastanozems are commonly formed and developed. Both soils in the Eurasian steppe are rich in Soil Organic Matter (SOM), which can support a luxuriant production of plant and biomass. SOM plays a fundamental role in the maintenance of the main soil properties and regimes related not just to the soil fertility. In the present study, Chernozemic and related soil samples under natural grasslands and arable lands were collected from nine profiles in Ukraine and Hungary to investigate the properties and characteristics of the SOM dynamics of humic substances in the Eurasian Steppe. Chernozemic soils collected from three profiles in Canada were also used to compare with the Eurasian soils and distinguish their features. Some physico-chemical properties of soil samples were analyzed to clarify the soil development and features of the Chernozemic profiles. Humification indexes (Δlog K and RF) were used to classify the Chernozemic humic acids and to examine the influences of natural and artificial impacts on degree of humification. ¹³C NMR spectroscopy was also applied to characterize the structure and composition of humic acids in the Eurasian Chernozems. The objectives of this study are to investigate 1) the effects of climate and moisture regimes on soil development and SOM dynamics of four Chernozemic subtypes in Ukraine, 2) the effects of agricultural impacts on changes in soil features and humic fractions of Chernozems under intensive management practices in Hungary and Canada, 3) the relationship between soil carbon degradation and expense of humic acids in the Eurasian steppe. The greater part of lands is covered by Chernozems and the related soils in Ukraine, where must be the central and representative Chernozemic zones in the Eurasian steppe. In the eastern part of Ukraine, the climosequence of the soils from the northern wetter zones to the southern drier zones can be distinctly observed. Under the moist conditions in the north, Typical Chernozems and Ordinary Chernozems, which can be distinguished by a deep black surface horizon with strongly-developed structures and the highly humified Type A humic acids, of which the RF value and aromaticity, which was calculated by expressing the amount of aromatic C (110 to 165 ppm) as ratio of aliphatic C + methoxyl C + carbohydrate C + aromatic C in the ¹³C NMR spectra, are remarkably high. Southern Chernozems and Dark Chestnuts are the common subtypes under the relatively dry moisture regime, the profiles of which can be characterized by a relatively thin dark-brown or brownish black surface horizon. These soils are also characterized by the Type A humic acids, however, the RF value is less than Typical and Ordinary Chernozems. The carbon stock as organic carbon and/or inorganic carbon through the profile is extremely high in either case, can support and assure a luxuriant production of plant and biomass. The lands covered by Chernozemic soils and the climatic conditions in such areas are suitable for wheat, barley and maize production, alongside other food crops and vegetables. The intensive agricultural practice would induce soil carbon degradation, due to low input of plant residues and high microbial decomposition of organic matter accompanied by plowing, resulting in irreversible decrease in the soil fertility. The soil colors of the surface horizons in the arable soils of Hungary and Canada are brownish black to dark brown, not real black, and the organic carbon contents in the topsoils are relatively lower than those of Ukraine, probably reflecting the soil carbon degradation through agricultural impacts. They are characterized by the Type A or B humic acids, of which Δlog K value is higher, the RF value is lower, and aromaticity is remarkably lower than those of the typical Type A humic acids observed in Ukraine. From the results, it was inferred that the intensive agricultural impacts can lead to changes not only in the SOM quantity but also in the SOM quality of humic acids, especially the decrease in the aromatic and highly-humified HAs of smaller particle size. The long-term cultivation and fertilization may contribute to the formation of labile (not stable) humic substances (larger particle size) at the expense of highly aromatic HAs (smaller particle size), which are more resistant to microbial decomposition and act as the binding agents of aggregate stability, resulting in deterioration of soil structure and depletion of soil fertility.