Investigation of the mechanisms driving ancient soil carbon stability in deep B-horizons of a giant podzol chronosequence (Cooloola)

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dc.contributor.authorJones, ARen_AU
dc.contributor.authorSanderman, Jen_AU
dc.contributor.authorDalal, RCen_AU
dc.contributor.authorJacobsen, GEen_AU
dc.contributor.authorGrandy, ASen_AU
dc.contributor.authorSchmidt, Sen_AU
dc.contributor.authorGupta, VVSRen_AU
dc.contributor.authorOudyn, Fen_AU
dc.date.accessioned2023-12-08T01:00:01Zen_AU
dc.date.available2023-12-08T01:00:01Zen_AU
dc.date.issued2018-12-13en_AU
dc.date.statistics2023-02-24en_AU
dc.description.abstractDespite deep subsoil soil organic matter (SOM) being rich in nutrients and highly palatable for microbial decomposition, it does not completely decompose, as indicated by universally observed increasing SOM turnover time (radiocarbon age) with depth. It is not entirely clear whether this is a result of unfavourable environmental conditions, mineral protection of organic matter or carbon substrate limitation due to distance from plant inputs. In this study, we have assessed the biogeochemical mechanisms driving ancient SOM stability in deep B-horizons of a giant podzol chronosequence (Cooloola sand dune chronosequence, Queensland, Australia). The chronosequence is characterised by a sequence of spodic B-horizons of increasing depth (from 0.5 to 15 m) with overlying leached E horizons comprised of weathered, clean quartz grains likewise extending with dune age. In this way, the chronosequence provides a unique model system to track depth-related changes to SOM composition and stability in the mineral-rich B-horizon at subsoil horizon depths rarely characterised before. Categorising products from pyrolysis-GC-MS into their respective origins revealed a clear transition of SOM composition primarily from plant-derived SOM (lignins, polysaccharides and N-bearing compounds) in the shallow A-horizons (0.1 m) to microbial-derived SOM (proteins, aromatics) in the deepest B horizon (15 m; Figure 1). These observations were accompanied by increasing SOM radiocarbon age with depth, indicating that the stabilisation of SOM was attributed to depth-related processes. Complexation with aluminium in the B-horizon appears to be the main driver of carbon accumulation in these podzols (more so than iron), pointing to geochemical stabilisation of SOM. In this work, we discuss whether proteins and aromatics have accumulated at depth due to preferential aluminium-complexation or if these compounds are the products of long-term degradation processes by the deep soil microbial community.en_AU
dc.identifier.citationJones, A., Sanderman, J., Dalal, R. C., Jacobsen, G. E., Grandy, S., Schmidt, S., Gupta, V., & Oudyn, F. (2018). Investigation of the mechanisms driving ancient soil carbon stability in deep B-horizons of a giant podzol chronosequence (Cooloola). Paper presented at the AGU Fall Meeting, Washington, D. C., 10 to 14 December 2018. Retrieved from: https://agu.confex.com/agu/fm18/meetingapp.cgi/Paper/344237en_AU
dc.identifier.conferenceenddate2018-12-14en_AU
dc.identifier.conferencenameAGU Fall Meeting 2018en_AU
dc.identifier.conferenceplaceWashington, D. C.en_AU
dc.identifier.conferencestartdate2018-12-10en_AU
dc.identifier.otherB41D-01en_AU
dc.identifier.urihttps://agu.confex.com/agu/fm18/meetingapp.cgi/Paper/344237en_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15276en_AU
dc.language.isoenen_AU
dc.publisherAmerican Geophysical Unionen_AU
dc.subjectSoilsen_AU
dc.subjectCarbonen_AU
dc.subjectQueenlanden_AU
dc.subjectAustraliaen_AU
dc.subjectOrganic matteren_AU
dc.subjectMineralsen_AU
dc.subjectPlantsen_AU
dc.subjectLeachingen_AU
dc.subjectQuartzen_AU
dc.subjectNutrientsen_AU
dc.titleInvestigation of the mechanisms driving ancient soil carbon stability in deep B-horizons of a giant podzol chronosequence (Cooloola)en_AU
dc.typeConference Paperen_AU
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