Microbiomorphs of the soddy solodic planosol and buried organic-accumulative quasi-clay soil of West Siberia

Abstract

The purpose of the study. Reconstruction of the conditions of solodic soils formation in the forest-steppe zone using soil characteristics and microbiomorphic analysis. Location and time of the study. The study was conducted in the forest-steppe zone (Kulunda, Novosibirsk region, Russia) where in the birch grove a pedocomplex consisting of a surface turf soddy soil and a buried soil. Soil samples were collected in 2014. Methods. Phytolith and some other microbiomorphs morphology, composition and relative abundance were analysed and their soil profile changes accessed. Results. Several peaks of the maximum accumulation of phytoliths were found in the microbiomorphic profile of the soddy solodic planosol. The largest number of phytoliths was found in the eluvial horizon. Phytoliths of steppe gramineous plants and elongated forms of dicotyledonous grasses (forbs, legumes, etc.) accounted for a significant proportion. Diatoms were present throughout the entire soil profile; sponge spicules were rare. Conclusion. At the first stage of its formation the buried soil went through the steppe stage of development (predominance of steppe grasses), followed by overgrowing of the steppe soil with meadow-forest vegetation at the current stage (increased share of forest and meadow grasses). The presence of diatomic shells is typical for soils experiencing recurrent (seasonal) flooding of the birch groves: a lot of snow usually accumulates there, and after the snowmelt water stays for a long time in summer. During wet years, when the groundwater level rises and merges with the surface waters, the phytolith forms characteristic of reeds, sponge spicules, and other indicators of increased moisture increased. Thus, the microbiomorphic composition of the buried organo-accumulative soil reflected its formation.