PHASING FEATURES OF THE SOIL-FORMING PROCESS IN AGROCHERNOZEMS OF WATERSHED PLATEU IN THE CENTRAL PART OF PODILLIA

Abstract

The development of the paleosoils during the warm stages (thermochrons) of the Pliocene and Pleistocene, being reflected in the structure of soil-loess and red-brown formations of Ukraine, is characterized by a clear regularity. This is manifested in the formation of complex soil layered constructions (pedocomplexes) reflecting the chronological stages of pedogenesis. Agrochernozems of watershed plateu in the central part of Podillia, formed on the loess rocks of the Late Pleistocene age, also show this general regularity of Pliocene-Pleistocene soil formation. Contrasting changes in the physic-geographical conditions of pedolitogenesis in the ancient Holocene (late glacial) and evolutionary trend of soil formation during the following Holocene periods lasting for 10–8 thousand years led to the formation of a two-stage Holocene soil layering on the plakor lands of the region, represented by chernozem-type soils. Morphological signs of staged soil formation are concentrated in one genetic profile, which, along with the sign of anthropization of landscapes and soil formation significantly complicates the detailed identification of soils and their historical and genetic analysis. The early stage of the local soil formation history is recorded in these soils in the form of solid-phase products of soil-forming processes (puppets, soil wormholes, coprolites, moles drains). These relict pedogenic formations are located in the lower part of the soil profile of agrochernozems. In general, in the soil profile of agrochernozems on the watershed plateu in the central part of Podillia the morphologically hidden stages of soil formation are noticeable, which is typical of the first half of the Holocene thermochron. The soil of the initial stage of pedogenesis correlates with the horizon of the mole loess P(h)k and the lower part of the transitional brown-colour horizon Phk or PhI. The humus profile of the plakor agrochernozems has soil characteristics of the early optimal stage, which lasted for 7–8 thousand years from the preboreal to the late subatlantic. There are no pedogenic signs of other stages of development of the pedocomplex. So, modern day soils of this region (agrochernozems) are polygenetic two-stage formations that have not reached the status of full-fledged pedocomplex. Key words: evolution; pedogenesis; agrochernozem; Holocene; stages of soil formation; pedocomplex; Podillіa.