Soil organic matter (SOM) concentration and composition are essential properties that affect most functions and ecosystem services. The relationship between soil and environmental covariates regarding SOM concentration and composition in various pools is not completely understood. This study aimed to identify the most influential drivers of SOM stabilization, focusing on arable lands in Hungary. Hungary is an ideal area for investigating SOM variability because it is at the meeting point of the three main climate effects that trigger a wide range of soil, land use, and topographical conditions. Overall, 87 soil samples were taken from the topsoil (2–20 cm) and fractionated (<20 µm) to separate the mineral phase-associated organic carbon (MAOC) and bulk pools. MAOC concentration varied on a wide range (0.5–14.1 %) and was the function of bulk SOM aromaticity and slope steepness, rather than land use, climatic conditions, or soil properties, indicating that MAOC is also affected by decomposition if the bulk OM is less available for the microbiome. Land use, especially in forest topsoils, reflects the elemental composition of the OM, focusing on the variations of residue composition. In contrast, aromaticity is rather related to soil and climate properties, suggesting increased relevance of transformation processes. As a consequence, SOM composition varies on a wide range in the topsoil, however, the lack of a definite trend at the county level suggests the complexity of the system and highlights the role of local circumstances.