Minerals in the three-component combination of agrochernozems in the Kamennaya Steppe

摘要

Properties and mineralogy of fine fractions separated from agrochernozems forming a three-component noncontrasting soil combination in the Kamennaya Steppe have been characterized. The soil cover consists of zooturbated (Haplic Chernozems (Clayic, Aric, Pachic, Calcaric)), migrational-mycelial (Haplic Chernozems (Clayic, Aric, Pachic)), and clay-illuvial (Luvic Chernozems (Clayic, Aric, Pachic)) agrochernozems. All the soils are deeply quasi-gleyed because of periodical groundwater rise. The mineralogy of the fraction 1 mu m includes irregular mica-smectite interstratifications, di- and trioctahedral hydromicas, imperfect kaolinite, and magnesium-iron chlorite. The profile distribution of these minerals slightly varies depending on the subtype of spot-forming soils. A uniform distribution of clay minerals is observed in zooturbated agrochernozem; a poorly manifested eluvial-illuvial distribution of the smectite phase is observed in the clay-illuvial agrochernozem. The fractions of fine (1-5 mu m) and medium (5-10 mu m) silt consist of quartz, micas, potassium feldspars, plagioclases, kaolinite, and chlorite. There is no dominant mineral, because the share of each mineral is lower than 35-45%. The silt fractions differ in the quartz-to-mica ratio. The medium silt fraction contains more quartz, and the fine silt fraction contains more micas.