UDC 631.48
Ubugunova V.I., Ubugunov VL., Varlamov E.B., Bazha S.N., Ubugunov L.L. MINERALOGICAL AND MATERIAL COMPOSITIONS OF SANDS AND SANDY SOILS IN THE CAINOZOIC DEPRESSIONS OF TRANSBAIKAL REGION // Arid Ecosystems. 2023. Vol. 29. № 4 (97). P. 81-92. | PDF
Characteristic of climatic, lithological and geomorphological conditions of formation of sandy soils of Transbaikal Region (Barguzin basin) is given. Main pedogenic processes were found to be cryo- and light-humus, accumulative-carbonate, and fawn-metamorphic. The processes of stratification and abrasion are expressed in soils of fallow lands. Moving sands are not involved in soil formation, but embryonic underdeveloped soils (layered-eolian, humus psammozems) have begun to develop with partial fixation of herbaceous and/or shrub vegetation. Composition of the rocks of the Angara-Vitim batholith, soil-forming sand, as well as the composition of minerals of fractions <1, 1-5 and >5 µm in cryo-humus and light-humus soils are presented for the first time. The regional features of parent sands have been determined to be carbonation, alkalinity and polymineral content, proceeded from the calcic-alkaline rocks. Sandy and silty soil fractions are of similar mineralogical composition with a high content of plagioclases and K-feldspars, and a low quartz amount. The silty fraction is composed by a mixed-layerd phase of illite-smectites interlayered with a single chlorite packets, di-three-octaedric illite, ferruginous chlorite, and kaolinite. Current soil formation is characterized by a low degree of chemical weathering (CIA, CIW, GM) and weak profile differentiation. An increased content of potassium and sodium are the feature of the material composition of sandy soils. Soils under the study correspond to the category of high-alkaline according to the values of total alkalinity. Biological activity is clearly distributed down soil profile. It was revealed that sandy soils have a potential risk of desertification with arable use: within the studied area, all arable lands and fallows located there are deflated to varying degrees. More than 70% of the area has been found to belong to very strongly deflated and strongly deflated. In such lands, humus soil layers are blown out, and carbonate horizons and even parent sands are exposed. The exposed middle horizons and sands are not effectively fertile. The yield of agricultural crops on such arable lands is very low. The process of natural restoration of vegetation cover on fallow lands is extremely difficult, and deflation ulcers practically do not overgrow. Alkalinity and carbonation of soil-forming sands are largely inhibited the processes of natural coenoses restoration.
Keywords: sandy soils, texture fractions, mineralogical composition, Transbaikal Region, Barguzin depression, desertification.
Funding. The work was carried out on the topics of state assignments: the Institute of General and Experimental Biology SB RAS «Evolutionary-genetic, biogeochemical and production functions of the soils of the Baikal region as a component of the biosphere, assessment of their resource potential and development of technologies for rational use and protection» (No. 121030100228-4) and the A.N. Severtsev Institute of Problems of Ecology and Evolution RAS «Historical ecology and biogeocenology» (No. 0109-2019-0007), with the support of the V.R. Filippov Buryat State Agricultural Academy (Theme I, Sub-theme I.03).
DOI: 10.24412/1993-3916-2023-4-81-92
EDN: IJOHVA