Cnudde, Veerle

De Neve, Stefaan

Maenhout, Peter

Sleutel, Steven

Van Hoorebeke, Luc

English

Ghent University Academic Bibliography

Geophysical Research AbstractsVol. 16, EGU2014-16389, 2014EGU General Assembly 2014© Author(s) 2014. CC Attribution 3.0 License.Soil pore structure and substrate C mineralizationSteven Sleutel (1), Peter Maenhout (1), Luc Vanhoorebeke (2), Veerle Cnudde (3), and Stefaan De Neve (1)(1) Dept. Soil Management Ghent University, Coupure Links 653 – 9000, Ghent, Belgium , (2) Department of Physics andAstronomy, Ghent University, Proeftuinstraat 86, Ghent, Belgium, (3) Department of Geology and Soil Science, GhentUniversity, Krijgslaan 281, S8, 9000 Ghent, BelgiumOur aim was to investigate the complex interactions between soil pore structure, soil biota and decomposition ofadded OM substrates. We report on a lab incubation experiment in which CO2 respiration from soil cores wasmonitored (headspace GC analysis) and an X-ray CT approach yielded soil pore size distributions. Such combineduse of X-ray CT with soil incubation studies was obstructed, until now, by many practical constraints such asCT-volume quality, limited resolution, scanning time and complex soil pore network quantification, which havelargely been overcome in this study.We incubated a sandy loam soil (with application of ground grass or sawdust) in 18 small aluminium rings(Ø 1 cm, h 1 cm). Bulk density was adjusted to 1.1 or 1.3 Mg m-3 (compaction) and 6 rings were filled at acoarser Coarse Sand:Fine Sand:Silt+Clay ratio. While compaction induced a strong reduction in the cumulative Cmineralization for both grass and sawdust substrates, artificial change to a coarser soil texture only reduced netC mineralization from the added sawdust. There thus appears to be a strong interaction effect between soil porestructure and substrate type on substrate decomposition. Correlation coefficients between the C mineralizationrates and volumes of 7 pore size classes (from the X-ray CT data) also showed an increasing positive correlationwith increasing pore size. Since any particulate organic matter initially present in the soil was removed prior to theexperiment (sieving, ashing the >53µm fraction and recombining with the <53µm fraction), the added OM can belocalized by means of X-ray CT. Through on-going image analysis the surrounding porosity of the added grass orsawdust particles is being quantified to further study the interaction between the soil pore structure and substratedecomposition.

Soil pore structure and substrate C mineralization

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Soil pore structure and substrate C mineralization

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Ghent University Academic Bibliography