Soil organic carbon in eastern Australia

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dc.contributor.authorHobley, Een_AU
dc.contributor.authorBaldock, JAen_AU
dc.contributor.authorHua, Qen_AU
dc.contributor.authorWilson, Ben_AU
dc.date.accessioned2021-07-28T01:04:21Zen_AU
dc.date.available2021-07-28T01:04:21Zen_AU
dc.date.issued2016-12-14en_AU
dc.date.statistics2021-07-13en_AU
dc.description.abstractWe investigated the drivers of SOC dynamics and depth distribution across eastern Australia using laboratory analyses (CN, fractionation, radiocarbon) coupled with modelling and machine learning. At over 1400 sites, surface SOC storage was driven by precipitation, whereas SOC depth distribution (0-30 cm) was influenced by land-use. Based upon these findings, 100 sites were selected for profile analysis (up to 1 m) of SOC and its component fractions - particulate (POC), humus (HOC) and resistant (ROC) organic carbon. Profile SOC content was modelled using an exponential model describing surface SOC content, SOC depth distribution and residual SOC at depth and the drivers of these parameters investigated via machine learning. Corroborating previous findings, surface SOC content was highly influenced by rainfall, whereas SOC depth distribution was influenced by land-use. At depth, site properties were the most important predictors of SOC. Cropped sites had significantly lower SOC content than native and grazed sites at depth, indicating that land-use influences SOC content throughout the profile. The machine learning algorithms identified depth as the key control on the proportion of all three fractions down the profile: POC decreased whereas HOC increased with increasing depth. POC was strongly linked with total SOC but HOC and ROC were driven more by climate and soil physico-chemical properties. Human influences (land-use and management) were not important to the fractions, implying that the controls humans can exert on SOC stability may be limited. A subset of 12 soil profiles was analysed for 14C. Radiocarbon content was affected strongly by land-use, with effects most pronounced at depth. Native systems had the youngest carbon down the profile, cropped systems had the oldest SOC. All fractions reacted to land-use change down the soil profile, indicating a lack of stability when the whole profile is viewed. These results indicate that natural systems act as a carbon pump into the soil, injecting young, fresh organic carbon down the entire profile. In contrast, managed systems are deprived of this input and are depleted in SOC at all depths. Our results strongly suggest that SOC storage in the region is input driven. © AGU 2016en_AU
dc.identifier.citationHobley, E., Baldock, J., Hua, Q & Wilson, B. (2016) Soil organic carbon in eastern Australia. Paper presented at the AGU Fall Meeting, San Francisco, California, 12 to 16 December 2016. Retrieved from: https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/138214en_AU
dc.identifier.conferenceenddate16 December 2016en_AU
dc.identifier.conferencenameAGU Fall Meetingen_AU
dc.identifier.conferenceplaceSan Francisco, Californiaen_AU
dc.identifier.conferencestartdate12 December 2016en_AU
dc.identifier.otherB32E-05en_AU
dc.identifier.urihttps://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/138214en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/11120en_AU
dc.language.isoenen_AU
dc.publisherAmerican Geophysical Union (AGU)en_AU
dc.subjectSoilsen_AU
dc.subjectLand useen_AU
dc.subjectCropsen_AU
dc.subjectGrazingen_AU
dc.subjectEcosystemsen_AU
dc.subjectRainen_AU
dc.subjectCarbon cycleen_AU
dc.subjectCarbon 14en_AU
dc.subjectAustraliaen_AU
dc.titleSoil organic carbon in eastern Australiaen_AU
dc.typeConference Abstracten_AU
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