A pragmatic quantitative model for soil organic carbon distribution in Eastern Australia

Jonathan Gray*, Thomas Bishop, Peter Smith, Nathan Robinson, Daniel Brough

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference proceeding contribution

1 Citation (Scopus)


A readily applied quantitative relationship between topsoil organic carbon levels and several major soil forming factors has been developed over eastern Australia using a dataset of 3652 soil profiles. The key soil forming covariates used were (i) climate: annual precipitation (precip) and annual maximum temperature (Tmax) (ii) parent material: assumed silica content, (iii) topography: a new "toposlope" index and (iv) land use: a modified land disturbance index (LDI). The multiple regression relationship, with soil organic carbon (orgC) on the natural log scale, achieved an R2 value of 0.54 with a residual standard error of loge 0.58 orgC%. Validation against 10% of points initially withheld revealed a root mean square error of 1.77 orgC% (on original non-log scale) and a median absolute error of 0.75 orgC%. Topsoil organic carbon levels appear to be predominantly controlled by maximum temperatures followed by precipitation and parent material composition with topography and land use being of lesser significance. The model is of moderate statistical strength and may provide a pragmatic tool for modelling and first approximation prediction of organic carbon levels in topsoils of eastern Australia. 

Original languageEnglish
Title of host publicationDigital soil assessments and beyond
Subtitle of host publicationproceedings of the 5th Global Workshop on Digital Soil Mapping, 2012, Sydney, Australia, 10-13 April 2012
EditorsBudiman Minasny, Brendan P. Malone, Alex B. McBratney
Place of PublicationLeiden, The Netherlands
PublisherCRC Press, Taylor & Francis Group
Number of pages6
ISBN (Electronic)9780203106105
ISBN (Print)9780415621557
Publication statusPublished - 2012
Externally publishedYes
Event5th Global Workshop on Digital Soil Mapping - Sydney, NSW, Australia
Duration: 10 Apr 201213 Apr 2012


Other5th Global Workshop on Digital Soil Mapping
CitySydney, NSW


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