Microrelief and spatial heterogeneity of soils on limestone, Sub Ural plateau, Russia: Attributes and mechanism of formation

Kovda, I.; Polyakov, D.; Ryabukha, A.; Lebedeva, M.; Khaydapova, D.

Авторы: Kovda Irina, Polyakov Dmitry, Ryabukha Anna, Lebedeva Marina, Khaydapova Dolgor
Журнал: Soil and Tillage Research
Том: 209
Номер: 5
Год издания: 2021
Издательство: Elsevier BV
Местоположение издательства: Netherlands
Первая страница: 1
Последняя страница: 11
Номер статьи: 104931
DOI: 10.1016/j.still.2021.104931
Аннотация: Complex soil cover and microrelief are common for arid environments. Understanding of the genesis andfunctioning of complex soil cover associated with microrelief is important to ensure optimal land use.We studied “chalk polygons” formed on the shallow limestone in the south of the European part of Russiaincluding microrelief and soil morphology, and the main physical and chemical properties of the representativehorizons.The microrelief consists of regular microhighs separated by polygonal network of elongated microdepressions.The soil cover includes Rendzic Endoleptic Calcaric Phaeozem (Relictiturbic, Tonguic) in microdepressions,Skeletic Calcaric Regosol (Relictiturbic, Raptic, Ochric) in microslopes and Skeletic Calcaric Regosol (Relicti-turbic, Raptic, Nudiyermik) in microhighs. The soils consist of three main layers with abrupt boundaries: darkgrey and grey, brownish-pale turbated, and white soft and hard limestone. Hard limestone from the bottom ofmicrodepressions is connected with the surface white “chalk caps” on the microhighs via the soft limestoneintrusions across the microslopes. Morphological analysis and micromorphology revealed a number of cryogenicfeatures such as large wedge-shaped structures in microdepressions, mosaic profile, turbated horizons, in-volutions and intrusions, platy soil structure. In the absence of permafrost a number of macromorphologicalattributes are apparently relict, while meso- and microcryogenic features could be modern, formed during winterfreezing.Limestone intrusions being relict determine the modern structure and functioning of the soil complex. Theyconsist of disintegrated limestone gravel incorporated into soft powdery limestone, and exhibit plastic behaviorwhen wet. Rheological characteristics confirm that the material of limestone intrusion has reduced shearresistance, and a lower range of elastic behavior and yield strength. Intrusions are the channels of watermigration from the wettest microdepressions to the dry microhights. Ice lenses form in wet limestone intrusionsin winter. Ice formation inside the limestone intrusions induces the frost lift and refreshment of the “chalk cap”.Thus, intrusions support the spatial and intra-profile heterogeneity, especially of morphology, texture andparticle-size distribution.Active “chalk polygons” have local distribution in steppe areas with shallow limestone and concave topog-raphy, and demonstrate unique morphology, and physical and chemical attributes. The arid climate, insufficientprecipitation, and annual self-restoration make grazing the optimal agricultural use of these landscapes.Otherwise relict genesis of “chalk polygons” and their unique attributes suggest their preservation as conser-vation areas.
Добавил в систему: Хайдапова Долгор Доржиевна

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Microrelief and spatial heterogeneity of soils on limestone, Sub Ural plateau, Russia: Attributes and mechanism of formationстатья

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