Morphology of forest ravined soil formation on deluvial loams

Abstract

The paper establishes the general features of the soil morphogenesis in ravined forests of Dnieper Prysamaria and genetic relationships of forest soils with zonal chernozem under herbaceous associations based on the detection of morphological properties that are «lithogenic», that is inherited from deluvial material and «pedogenic» features formed directly in the forest soil. The study area is located on the Dnieper Prysamaria (Dnipropetrovsk region) within the area of the steppes. The trial areas are incorporated in the upper Deep ravine, located in the upland part of watershed landscape. Catena is represented by five typical sections – between edging of the ravined forest and the field in the middle thirds of the slopes of the northern and southern exposures and in the thalweg of the ravine. Samples for meso-morphological studies were selected by genetic horizons, samples for soil horizons were selected using a soil drill. Basic morphological characteristics were determined in the laboratory (except for the hardness index). The mathematical processing of the results was carried out by methods of nonparametric statistics (method K-means). It was found that, despite the temporal and spatial disorder of deluvial material deposition processes and the differences of the water regime in the thalweg on the slopes, in the ravined biogeocenoses the forest soils are formed with common features of morphological organization of the genetic profile of the individual and morphological properties. The uniformity of the general structure is shown in a set sequence and the power of the genetic horizons, polycyclic and texture eluvial-illuvial differentiation of the genetic profile. The uniformity of the changes in the profile of the individual morphological properties is shown in the form of colour options of genetic horizons (due to humus content talus deposits), changing the particle size distribution of horizons in accordance with the general differentiation profile on eluvial and illuvial (due lessivage) part, changes in the morphology and dimensions of structural units related to changes in the structure of hardness horizons intensive leaching of carbonates from the profile of forest soils. The necessity of research processes clayization profile in situ, their role in the morphogenesis of compacted horizons are noted. There are two groups of properties that make it possible to analyze the micromorphology level communication between the soils in the catena. The first – a lithogenic conditionally or diluvial material properties, which persist for a long time in a forest soil – granulometry and less coloration horizons. The second – a pathogenic properties, sharply differing in the studied soils associated with the peculiarities of morphogenesis of a particular genetic profile and specific genetic horizon. These include the level of occurrence of carbonates in the profile and intensity of effervescence, the morphology of the structural units, the hardness of the genetic horizons, the level of spot colour. Cluster analysis identified a statistically illustrates the differences between the morphological structure of the soil catena, combining in one cluster the ravined soils on deluvial deposits under forest vegetation, and in the other – the soils on the loess under herbaceous vegetation. The contrast of differences increases down the profile.