If we want to develop farming on soil effectively and ecologically, we have to know the soil characteristics, the reasons for the potential low fertility and the ways how to eliminate them. Only this approach allows the rational utilization of the soil fund and achievement of the high effectiveness of the costs needed for the stabilization and increase of fertility and land capability. Recently, many scientific teams have focused their attention on the biochar, a lot of recommendations have been published which are dealing with its application into soil. However, the principal attention has been drawn to the impact of biochar on the particular soils and under the particular conditions. Far less information has been presented about the mutual interactions between the further significant agronomical factors in the combination with biochar. In this primary study, we analyze two new experiments established in the southwest part of Slovakia at the 1 Dolná Streda (sandy soil) and 2 Veľké Uľany (loamy soil) Localities. We discussed (1) the impact of the individual factors on the changes of soil characteristics, and (2) the impact of the individual interactions, such as: soil class – fertilization – biochar on the changes of the soil characteristics. The results indicated that the most significant factor, which influences the monitored soil parameters, is the soil class. The fertilization proved to be a factor which has a negative impact on the humus parameters; on the other hand, it improved the soil sorption. Biochar increased the content of the organic substances in soil and also its environmental effect of retention and immobilization of harmful elements and its positive effect on the soil structure was indicated. The highest frequency of the interactions between the monitored parameters related to the changes of soil characteristics was recorded in the combination fertilization x biochar, and also the soil class x fertilization x biochar.