Soil & Water Res., 2016, 11(4):259-266 | DOI: 10.17221/182/2015-SWR

Labile forms of carbon and soil aggregatesOriginal Paper

Erika Tobiašová¹, Gabriela Barančíková², Erika Gömöryová³, Jarmila Makovníková², Rastislav Skalský², Ján Halas², Štefan Koco⁴, Zuzana Tarasovičová², Jozef Takáč², Miroslav Špaňo¹

¹ Department of Soil Science, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture, Nitra, Slovak Republic

² Soil Science and Conservation Research Institute - National Agriculture and Food Centre, Bratislava, Slovak Republic

³ Faculty of Forestry, Technical University in Zvolen, Zvolen, Slovak Republic

⁴ Department of Geography and Applied Geoinformatics, University of Presov, Prešov, Slovak Republic

Soil organic matter (SOM) plays an important role in the soil aggregation and vice versa, its incorporation into the soil aggregates is one of the mechanisms of soil organic carbon stabilization. In this study the influence of labile carbon fractions on the fractions of dry-sieved (DSA) and wet-sieved (WSA) macro-aggregates and the relationship between the content of total organic carbon (TOC) and its labile fractions in the soil and in the fractions of macro-aggregates were determined. The experiment included six soil types (Eutric Fluvisol, Mollic Fluvisol, Haplic Chernozem, Haplic Luvisol, Eutric Cambisol, Rendzic Leptosol) in four ecosystems (forest, meadow, urban, and agro-ecosystem). In the case of DSA, the contents of labile fractions of carbon, in particular cold water extractable organic carbon (CWEOC) and hot water extractable organic carbon (HWEOC), had a higher impact on the proportions of larger fractions of macro-aggregates (3-7 mm), while in the case of WSA, the impact of labile fractions of carbon, mainly labile carbon (C_L) oxidizable with KMnO₄, was higher on the proportions of smaller fractions of aggregates (0.25-1 mm). The WSA size fraction of 0.5-1 mm seems an important indicator of changes in the ecosystems and its amounts were in a negative correlation with C_L (r = -0.317; P < 0.05) and HWEOC (r = -0.356; P < 0.05). In the WSA and DSA size fractions 0.5-1 mm, the highest variability in the contents of TOC and C_L was recorded in the forest ecosystem > meadow ecosystem > urban ecosystem > agro-ecosystem. The higher were the inputs of organic substances into the soil, the greater was the variability in their incorporation into the soil aggregates. The influence of the content of TOC and its labile forms on their contents in the DSA and WSA was different, and the contents of TOC and C_L in the aggregates were more significantly affected by the C_L content than by water soluble carbon. In the case of WSA fractions, their carbon content was more affected in the 1-2 mm than in 0.5-1 mm fraction.

Keywords: ecosystem; labile carbon; macro-aggregates; soil type

Published: December 31, 2016  Show citation