Complex soil cover and microrelief are common for arid environments. Understanding of the genesis and functioning 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 Russia including microrelief and soil morphology, and the main physical and chemical properties of the representative horizons.

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 (Relictiturbic, Raptic, Nudiyermik) in microhighs. The soils consist of three main layers with abrupt boundaries: dark grey and grey, brownish-pale turbated, and white soft and hard limestone. Hard limestone from the bottom of microdepressions is connected with the surface white “chalk caps” on the microhighs via the soft limestone intrusions across the microslopes. Morphological analysis and micromorphology revealed a number of cryogenic features such as large wedge-shaped structures in microdepressions, mosaic profile, turbated horizons, involutions and intrusions, platy soil structure. In the absence of permafrost a number of macromorphological attributes are apparently relict, while meso- and microcryogenic features could be modern, formed during winter freezing.

Limestone intrusions being relict determine the modern structure and functioning of the soil complex. They consist of disintegrated limestone gravel incorporated into soft powdery limestone, and exhibit plastic behavior when wet. Rheological characteristics confirm that the material of limestone intrusion has reduced shear resistance, and a lower range of elastic behavior and yield strength. Intrusions are the channels of water migration from the wettest microdepressions to the dry microhights. Ice lenses form in wet limestone intrusions in 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 and particle-size distribution.

Active “chalk polygons” have local distribution in steppe areas with shallow limestone and concave topography, and demonstrate unique morphology, and physical and chemical attributes. The arid climate, insufficient precipitation, 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 conservation areas.

复杂的土壤覆盖和微浮雕在干旱环境中很常见。了解与微浮雕相关的复杂土壤覆盖的成因和功能对于确保最佳土地利用非常重要。

我们研究了在俄罗斯欧洲南部南部浅层石灰岩上形成的“粉笔多边形”，包括微浮雕和土壤形态，以及代表层的主要物理和化学性质。

微浮雕由规则的微高组成，微微高被细长的微凹陷的多边形网络分隔开。土壤覆盖包括微坡度中的Rendzic内生钙镁Phaeozem（Relictiturbic，Tonguic），微坡度中的Skeletic Calcaric Regosol（Relictiturbic，Raptic，Ochric）和Microhighs中的Skeletic Calcaric Regosol（Relictiturbic，Raptic，Nudiyermik）。土壤由三个主要的边界层组成，边界是突变的：深灰色和灰色，淡褐色的湍流和白色的软硬石灰石。来自微凹陷底部的硬质石灰石通过微斜坡上的软质石灰岩侵入体与微高地上的表面白色“粉笔帽”相连。形态分析和微观形态揭示了许多低温特征，例如微凹陷中的大楔形结构，镶嵌轮廓，动荡的地平线，内卷和侵入，板状土壤结构。在没有多年冻土的情况下，显然存在许多宏观形态学特征，而中低温和微低温特征可能是现代的，形成于冬季冻结期间。

遗留的石灰岩侵入物决定了土壤复合物的现代结构和功能。它们由掺入软粉状石灰石中的崩解性石灰石碎石组成，并在湿润时表现出可塑性。流变特性证实，石灰岩侵入体的材料具有降低的抗剪切性，以及较低的弹性和屈服强度范围。入侵是水从最湿的微洼地迁移到干微高地的渠道。冬季，湿的石灰岩侵入物中会形成冰晶。石灰岩侵入体内部的冰层引起霜冻的提升和“粉笔帽”的更新。因此，入侵支持空间和轮廓内异质性，特别是形态，纹理和粒度分布。

活跃的“粉笔多边形”在浅石灰岩和凹形地形的草原地区具有局部分布，并表现出独特的形态，物理和化学属性。干旱的气候，降水不足以及每年的自我修复使这些景观成为放牧的最佳农业方式。否则，“粉笔多边形”的遗迹成因及其独特属性建议将其保存为保护区。