One of the most important tasks of modern geology for agriculture is to provide information for agriculture, primarily for plant cultivation and sylviculture with the study of interactions among soil, parent rock and groundwater. Our case studies showed unambiguously that the parent material on which the soil really formed has to have a vital role in soil science research. Our research proved that soil forms just from loose sediments, even in areas build up by solid rocks, which has a crucial influence on the type, quality and fertility of soils through its mineral composition, physical and chemical characteristics.
Soil forming sediment is defined as the loose sediment on the surface, which is the upper layer of near-surface rocks in flat and hilly regions, and it is the upper layer of the sediment-ensemble situated on the undisturbed bedrock (i.e. parent rock) in mountainous areas. Considering its origin, these sediments could be autochthon and/or allochton.
In regions of hills, mountains and mountain fronts for the study of the soil forming sediment the soil—parent material—bedrock system have to be taken into account. The loose sediment covering the solid rock is originated from the given rock type as debris and/or it settled on that by some kind of geological processes, have to be correctly defined. In these areas the bedrock, the loose sediment above it (soil forming sediment) and the soil type are under study. In the recent past our studies proved that the thickness, the composition and genetics (the relationship with the surface of the older solid rocks situated below) of the young unconsolidated sediments determine the soil characteristic in the studied mountainous sites (e.g. the Szendrُi Mountain, the Bükk Mountain).
In plain areas the soil—parent rock—groundwater system has to be studied as a whole down to the saturated zone. In the analysis of typical parent rock development of the near-surface formations, loose sediments are classified by the grain size and the layers in the uppermost 10 metres.