Over the past 90 years, anthropogenic degradation of soil caused by alkaline, magnesium-rich dust deposit has presented a serious problem near magnesite processing factories in Jelšava and in Lubeník (Slovakia). Since 1984, adopted measures have improved the emissions situation; however, this has resulted in insufficient attention being paid to soil properties. Therefore, the objective of this study was to investigate the chemical and biological soil properties in 14 sampling sites at different distances from factories, and based on the results, to propose further use of affected land. Results revealed the highest excess of magnesium in the sampling sites near both factories. Total and available Mg significantly affected soil pH, carbonate content, and conductivity, while the content of monitored heavy metals was not related to Mg. In localities with higher excess of available Mg, lower stock of newly formed organic matter prevailed with consequently weaker enzymatic activity. Therefore, enrichment by organic matter provides a measure to support the biological activity of soil. Because alkaline emissions have decreased by 99.8% since 1970, the application of classical measures (mechanical removal of the Mg-rich crust, incorporation of gypsum and manure to the soil), or newer methods (growing of Mg hyper-accumulating plants) can offer more lasting positive effects than those of 50 years ago. This study concluded that Mg-rich, alkaline dust deposition causes long-lasting soil degradation.