Acid-base buffering of soils in transitional and transitional-accumulative positions of undisturbed southern-taiga landscapes

• Published in: Eurasian soil science 2012-05, Vol.45 (5), p.503-513
• Main Authors: Rusakova, E. S., Ishkova, I. V., Tolpeshta, I. I., Sokolova, T. A.
• Format: Article
• Language: English
• Subjects: Aluminum; Aluminum compounds; Earth and Environmental Science; Earth Sciences; Floodplains; Geochemistry; Geomorphology; Geotechnical Engineering & Applied Earth Sciences; Leaching; Mineralogy; Moisture content; Organic matter; Oxalates; Oxalic acid; Soil Chemistry; Soil horizons; Soil moisture; Soil sciences; Soil treatment; Soil water; Soils; Taiga & tundra
• ISSN: 1064-2293; 1556-195X
• DOI: 10.1134/S1064229312050110

The method of continuous potentiometric titration (CPT) of soil water suspensions was used to evaluate the acid-base buffering of samples from the major genetic horizons of podzolic soils on a slope and soddy gley soils on the adjacent floodplain of a rivulet. In the soils of the slope, the buffering to acid upon titration from the pH of the initial titration point (ITP) to pH 3 in all the horizons was 1.5–2.0 times lower than that in the podzolic soils of the leveled interfluve, which could be due to the active leaching of exchangeable bases and oxalate-soluble aluminum and iron compounds with the later soil flows. In the soddy gley soils, the buffering to acid in the mineral horizons was 2–10 times higher than that in the podzolic soils. A direct dependence of the soil buffering to acid on the total content of exchangeable bases and on the content of oxalate-soluble aluminum compounds was found. A direct dependence of the buffering to basic upon titration from the ITP to pH 10 on the contents of the oxalate-soluble aluminum and organic matter was observed in the mineral horizons of all the studied soils. The soil treatment with Tamm’s reagent resulted in the decrease of the buffering to acid in the soddy gley soils of the floodplain, as well as in the decrease of the buffering to basic in the soils on the slopes and in the soddy gley soils. It was also found that the redistribution of the mobile aluminum compounds between the eluvial, transitional, and transitional-accumulative positions in the undisturbed southern taiga landscapes leads to significant spatial differentiation of the acid-base buffering of the mineral soil horizons with a considerable increase in the buffer capacity of the soils within the transitional-accumulative terrain positions.