Vkunkel Thesis
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PREDICTORS OF SOIL ORGANIC CARBON IN AGRICULTURAL PASTURES VEIKKO R KUNKEL B Env Sci (Hons I) (University of New England) A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in Physical Geography December 2017 This research was supported by an Australian Government Research Training Program (RTP) Scholarship Statement of Originality I hereby certify that the work embodied in the thesis is my own work, conducted under normal supervision. The thesis contains no material which has been accepted, or is being examined, for the award of any other degree or diploma in any university or other tertiary institution and, to the best of my knowledge and belief, contains no material previously published or written by another person, except where due reference has been made in the text. I give consent to the final version of my thesis being made available worldwide when deposited in the University’s Digital Repository, subject to the provisions of the Copyright Act 1968 and any approved embargo. Maps throughout this book were created using ArcGIS® software by Esri. ArcGIS® and ArcMap™ are the intellectual property of Esri and are used herein under license. Copyright © Esri. All rights reserved. For more information about Esri® software, please visit www.esri.com. …………………………… (December 2017) ii ACKNOWLEDGEMENTS I would like to thank my supervisors, A/P Greg Hancock and Dr. Tony Wells, for their support, guidance, patience and assistance throughout the course of my PhD. Thank you to Chris Dever, Alisa Williamson and Matthew Braggins for their assistance in collecting field data, and thanks again to Chris Dever for laboratory support. Thanks also to Cristina Martinez for provision of 2006 soil data. Thanks goes to Olivier Rey-Lescure for providing data and suggestions in GIS processing. Thanks also goes to Graham Lancaster from the Environmental Analysis Laboratory (EAL), Lismore, for the prompt analysis of soil samples for C and N using dry combustion (LECO). Thanks to the landholders and managers of the Merriwa district, upon whose properties the field work was conducted. I respectfully acknowledge the past and present traditional Indigenous custodians of the land where the study site is located. To all my family, friends and fellow PhD students, thank you for your support and encouragement. iii ABBREVIATIONS 137Cs – Caesium-137 AGB – Above-Ground Biomass APAR – Absorbed Photosynthetically Active Radiation BD – Bulk Density C – Carbon C:N – Carbon:Nitrogen Ratio CO2 – Carbon Dioxide DEM – Digital Elevation Model DEM-H – Hydrologically conditioned and drainage enforced Digital Elevation Model DSA – Digital Soil Assessment DSRA – Digital Soil Risk Assessment DTM – Digital Terrain Model EO-1 – Earth Observer 1 ETM+ - Enhanced Thematic Mapper EVI – Enhanced Vegetation Index GA – Geoscience Australia GIS – Geographical Information Systems GVF – Green Vegetation Fraction HDF – Hierarchical Data Format IR – Infra-Red iv ISSS – International Society of Soil Science kh – horizontal or plan curvature kv – vertical or profile curvature LAI – Leaf Area Index LECO – Laboratory Equipment Corporation LIC – Lithogenic Organic Carbon LPI – Land and Property Information MIR – Mid Infra-Red MODIS - Moderate Resolution Imaging Spectroradiometer MSS – Multispectral Scanner System NIR – Near Infra-Red NDVI – Normalised Difference Vegetation Index NOAA-AVHRR – National Oceanic and Atmospheric Administration-Advanced Very High Resolution Radiometer NPP – Net Primary Production OLI – Operational Land Imager OM – Organic matter PIC – Pedogenic Organic Carbon QA – Quality Assurance RUSLE – Revised Universal Soil Loss Equation SAC-C – Scientific Application Satellite-C v SLC – Scan Line Corrector SIC – Soil Inorganic Carbon SOC – Soil Organic Carbon SRTM – Shuttle Radar Topography Mission SWIR – Short Wave Infra-Red TM – Thematic Mapper USDA – United States Department of Agriculture USLE – Universal Soil Loss Equation VI – Vegetation Index VIF – Variance Inflation Factor WGS84 – World Geodetic System 84 Yr – Year vi CONTENTS Statement of Originality ...................................................................... ii Acknowledgements ............................................................................ iii Abbreviations ..................................................................................... iv Contents ............................................................................................ vii Abstract ............................................................................................. xii List of Figures .................................................................................. xiv List of Tables .................................................................................. xxii Chapter 1. Introduction .................................................................... 1-1 1.1. Introduction ..................................................................................................................... 1-1 1.2. The global carbon cycle .................................................................................................. 1-3 1.3. The soil carbon pool........................................................................................................ 1-4 1.3.1. SOC sequestration ................................................................................................. 1-5 1.4. Quantifying SOC Spatiotemporal Distribution ............................................................... 1-6 1.4.1. Plant carbon inputs ................................................................................................ 1-8 1.4.2. Geomorphology: topography .............................................................................. 1-10 1.5. Rational for the Current Study ...................................................................................... 1-11 1.5.1. Significance of the study site .............................................................................. 1-13 1.5.2. Aims and objectives ............................................................................................ 1-15 1.6. Thesis Structure ............................................................................................................ 1-16 Chapter 2. Study Site Description .................................................... 2-1 2.1. Introduction ..................................................................................................................... 2-1 2.2. Study Location ................................................................................................................ 2-1 vii 2.3. Climate ............................................................................................................................ 2-4 2.3.1. Climate Data ......................................................................................................... 2-4 2.3.2. Rainfall .................................................................................................................. 2-5 2.3.3. Soil Temperature ................................................................................................... 2-8 2.4. Geology ......................................................................................................................... 2-10 2.5. Landforms, Land Systems and Soils ............................................................................. 2-13 2.6. Terrain ........................................................................................................................... 2-20 2.7. Land-use and land-use history ...................................................................................... 2-23 2.8. Summary Comparison of Krui River and Merriwa River Catchments ......................... 2-26 Chapter 3. Methods .......................................................................... 3-1 3.1. Introduction ..................................................................................................................... 3-1 3.2. Field Sampling ................................................................................................................ 3-2 3.2.1. Sampling Periods .................................................................................................. 3-2 3.2.2. Sampling Design ................................................................................................... 3-2 3.2.3. Sampling Processes ............................................................................................... 3-4 3.2.4. Sampling Density .................................................................................................. 3-9 3.3. Laboratory Procedures .................................................................................................. 3-10 3.3.1. Field Sample Preparation .................................................................................... 3-10 3.3.2. SOC Analysis ...................................................................................................... 3-10 3.3.3. 137Cs Analysis...................................................................................................... 3-11 3.3.4. Particle Size Analysis ......................................................................................... 3-15 3.3.5. pH analysis .......................................................................................................... 3-15 3.4. DEM processing...........................................................................................................