Modern tendencies of changes in the properties of virgin and post-irrigational soils of solonetzic complexes on the Privolzhskaya ridge

Abstract

The study of post-irrigational and virgin soils of solonetzic complexes on the Privolzhskaya sandy ridge has shown that the morphological features of paleohydromorphism and the features acquired during the 30-year-long irrigation period are well preserved in the soil profiles. After the cessation of irrigation, the upper boundary of effervescence has shifted closer to the soil’s surface; fine-crystalline gypsum has appeared in channel pores. When the groundwater level is deeper than 4 m, the boundary of effervescence is higher than the boundary of the gypsum concentrations. When the groundwater level is about 3 m, these two boundaries coincide. If the groundwater level is higher than 2.5 m, the boundary of the effervescence is found deeper than the boundary of the gypsum concentrations. Salinization and solonetzization of the post-irrigational soils have not been identified. In the virgin soils with the groundwater level of 2.3–3.0 m, the content of exchangeable sodium in the upper 30 cm is similar to that in the post-irrigational soils. In the deeper layers, the exchangeable sodium content in the solonetzes and chestnut soils rises up to 25% and more; in the meadow-chestnut soils, it constitutes up to 4% of the sum of exchangeable bases.