Bioavailability and isotopic composition of CO2 released from incubated soil organic matter fractions
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Bioavailability and isotopic composition of CO2 released from incubated soil organic matter fractions. / Mueller, Carsten W.; Gutsch, Martin; Kothieringer, Katja; Leifeld, Jens; Rethemeyer, Janet; Brueggemann, Nicolas; Kögel-Knabner, Ingrid.
I: Soil Biology and Biochemistry, Bind 69, 02.2014, s. 168-178.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Bioavailability and isotopic composition of CO2 released from incubated soil organic matter fractions
AU - Mueller, Carsten W.
AU - Gutsch, Martin
AU - Kothieringer, Katja
AU - Leifeld, Jens
AU - Rethemeyer, Janet
AU - Brueggemann, Nicolas
AU - Kögel-Knabner, Ingrid
PY - 2014/2
Y1 - 2014/2
N2 - The stabilization of soil organic matter (SOM) is triggered by three main mechanisms: (i) low bioavailability due to aggregation, (ii) recalcitrance due to the chemical structure, and (iii) association of the SOM with mineral surfaces. In the present study we used particle size SOM fractions (sand, silt and clay), derived from the Ah soil horizon from a Norway spruce forest in Southern Germany, to study the effects of different stabilization mechanisms on the bioavailability of soil organic carbon (SOC) in a one year incubation experiment. The respired CO2 was hourly recorded, additionally 13CO2 was analysed 20 times and 14CO2 three times during the incubation experiment. To better differentiate between particulate OM (POM) and mineral associated OM (MIN), the incubated fractions and bulk soil were separated according to density (1.8gcm-3) after the incubation experiment. 13C-CPMAS NMR spectroscopy was used to study the chemical composition of the incubated samples. We demonstrate a clear increase in SOM bioavailability due to aggregate disruption, as the calculated theoretical CO2 evolution of the SOM fractions recombined by calculation was 43.8% higher in relation to the intact bulk soil. The incubated sand fraction, dominated by POM rich in O/N-alkyl C, showed a prolonged bioavailability of SOC moieties with mean residence times (MRT) of 78 years. Interestingly, the silt fraction, dominated by highly aliphatic, more recalcitrant POM, showed low mineralization rates and slow MRT's (192 years) close to values for the clay fraction (171 years), which contained a large amount of mineral-associated SOM. The recorded 13/12CO2 signatures showed a high depletion in 13C during the initial stage of the incubation, but an enrichment of the respired 13CO2 of up to 3.4‰ relative to the incubated SOM was observed over longer time periods (after 3 and 4 days for bulk soil and sand, respectively, and after 14 days for silt and clay). Therefore, we found no evidence for a 13C enrichment of SOM as driven by metabolic isotopic fractionation during microbial SOM mineralization, but an indication of a change in the isotopic composition of the C-source over time.
AB - The stabilization of soil organic matter (SOM) is triggered by three main mechanisms: (i) low bioavailability due to aggregation, (ii) recalcitrance due to the chemical structure, and (iii) association of the SOM with mineral surfaces. In the present study we used particle size SOM fractions (sand, silt and clay), derived from the Ah soil horizon from a Norway spruce forest in Southern Germany, to study the effects of different stabilization mechanisms on the bioavailability of soil organic carbon (SOC) in a one year incubation experiment. The respired CO2 was hourly recorded, additionally 13CO2 was analysed 20 times and 14CO2 three times during the incubation experiment. To better differentiate between particulate OM (POM) and mineral associated OM (MIN), the incubated fractions and bulk soil were separated according to density (1.8gcm-3) after the incubation experiment. 13C-CPMAS NMR spectroscopy was used to study the chemical composition of the incubated samples. We demonstrate a clear increase in SOM bioavailability due to aggregate disruption, as the calculated theoretical CO2 evolution of the SOM fractions recombined by calculation was 43.8% higher in relation to the intact bulk soil. The incubated sand fraction, dominated by POM rich in O/N-alkyl C, showed a prolonged bioavailability of SOC moieties with mean residence times (MRT) of 78 years. Interestingly, the silt fraction, dominated by highly aliphatic, more recalcitrant POM, showed low mineralization rates and slow MRT's (192 years) close to values for the clay fraction (171 years), which contained a large amount of mineral-associated SOM. The recorded 13/12CO2 signatures showed a high depletion in 13C during the initial stage of the incubation, but an enrichment of the respired 13CO2 of up to 3.4‰ relative to the incubated SOM was observed over longer time periods (after 3 and 4 days for bulk soil and sand, respectively, and after 14 days for silt and clay). Therefore, we found no evidence for a 13C enrichment of SOM as driven by metabolic isotopic fractionation during microbial SOM mineralization, but an indication of a change in the isotopic composition of the C-source over time.
KW - Density fractionation
KW - Heterotrophic respiration
KW - Laboratory incubation
KW - Mean residence time
KW - Microbial biomass
KW - Particle size fractionation
U2 - 10.1016/j.soilbio.2013.11.006
DO - 10.1016/j.soilbio.2013.11.006
M3 - Journal article
AN - SCOPUS:84896932221
VL - 69
SP - 168
EP - 178
JO - Soil Biology & Biochemistry
JF - Soil Biology & Biochemistry
SN - 0038-0717
ER -
ID: 239161870