Composition, Properties, and Phosphate Status of Permafrost Soils Developed on Noncalcareous Soil-Forming Rocks in Southern Yakutia

Abstract— The composition, properties, and the phosphate status of six permafrost soil types developed on noncalcareous soil-forming rocks in cold humid climate of South Yakutia have been studied. Four out of six were mineral soils and included illuvial-ferruginous podzol (Albic Podzol (Loamic, Turbic)), typical burozem (Eutric Cambisol (Loamic)), pale-brown gleyic (Umbric Turbic Cryosol (Loamic)), and alluvial dark humus (Eutric Fluvisol (Arenic, Gelic, Humic)) soils; and two were organic soils, i.e., meadow-bog (Histic Reductaquic Cryosol (Dystric))and peat-bog (Fibric Cryic Histosol (Dystric)) soils. The weighted average total content of phosphates determined by the Sanders and Williams method, varied within 60.4-301.4 and 627.7–952.8 mg P2O5 per 100 g soil in mineral and bog soils, respectively. Among mineral soils, the minimal total amount of phosphates was found in podzol, and the maximum, in burozem. In the mineral soils of South Yakutia, the average relative content of organic and mineral phosphorus was equal to 35–52 and 48–65%, respectively; and in organic soils, it was estimated at 82–85 and 15–18%, respectively. For the bulk of the studied soils in the region, aluminum and iron phosphates appeared to be the predominant fractions of mineral phosphates determined by the Chang–Jackson method, constituting 78–91% of the total amount of all phosphate fractions. The average content of iron phosphates was equal to 53–79% in these soils.