A First Generation Digital Soil Map of a Portion of the Uasin Gishu Plateau, Kenya John A
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Purdue University Purdue e-Pubs Open Access Theses Theses and Dissertations Summer 2014 A first generation digital soil map of a portion of the Uasin Gishu Plateau, Kenya John A. Lomurut Purdue University Follow this and additional works at: https://docs.lib.purdue.edu/open_access_theses Recommended Citation Lomurut, John A., "A first generation digital soil map of a portion of the Uasin Gishu Plateau, Kenya" (2014). Open Access Theses. 649. https://docs.lib.purdue.edu/open_access_theses/649 This document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact [email protected] for additional information. i A FIRST GENERATION DIGITAL SOIL MAP OF A PORTION OF THE UASIN GISHU PLATEAU, KENYA A Thesis Submitted to the Faculty of Purdue University by John A Lomurut In Partial Fulfillment of the Requirements for the Degree of Master of Science in Agronomy August 2014 Purdue University West Lafayette, Indiana ii To my parents Lmebiki & Hafaro, Lomurut iii ACKNOWLEDGEMENTS It is an honor to acknowledge the many people who made this project a success. First, I would like to thank Dr. Darrell Schulze, my major advisor, for believing in my capabilities and giving me an opportunity to grow both professionally and as a person under your supervision. Thank you for giving me the opportunity to be part of this research team. You have been part of this work at every step on the way and for that, I am truly grateful. I would also like to thank Dr. Phillip Owens, my other advisor, for his guidance throughout the research period; this work could not be complete without your unfailing support. Dr. George Van Scoyoc, thank you for accepting to be part of my committee. Thanks to Dr. Cornelius Serrem for his assistance with the field work in Kenya. I am also indebted to Robert Brown, Joshua Minai, and Mercy Ngunjiri for your help in one-way or the other. To my parents, brothers, sisters, and uncles, thank you for molding me to what I am today. It is truly a blessing to have you in my life. Last but not least, my heart goes out the love of my life, Agnes, for all the support you accorded me. I can’t thank you enough! iv TABLE OF CONTENTS Page LIST OF TABLES………………………………………………………………………..vi LIST OF FIGURES……………………………………..……………………………….vii ABSTRACT ……………………………………………………………………………viii CHAPTER 1. INTRODUCTION ................................................................................. 1 1.1 Overview of African Agriculture and Soils .................................................................. 1 1.1.1 Africa………………………………………………………………...1 1.1.2 Kenya………………………………………………………………..4 1.1.3 Uasin Gishu County ............................................................................7 1.2 Digital Soil Maps (DSM) .............................................................................................. 8 1.2.1 Soil-Landscape Relationships .............................................................9 1.3 Clay mineralogy .......................................................................................................... 13 1.4 Objective…………. .................................................................................................... 13 CHAPTER 2. MATERIALS AND METHODS ........................................................ 14 2.1 Study Area.. ................................................................................................................ 14 2.2 Sampling procedure .................................................................................................... 17 2.3 Sample Analysis.......................................................................................................... 21 2.3.1 Physical characterization ...................................................................21 2.3.2 Chemical Characterization. ...............................................................21 2.4 Clay Mineralogy ......................................................................................................... 22 2.4.1 SamplPreparation for X-ray Diffraction Analysis ............................22 2.4.2 X-ray diffraction analysis. .................................................................23 2.5 Statistical Analysis ...................................................................................................... 24 2.6 Digital soil class map .................................................................................................. 24 2.6.1 Environmental variables....................................................................24 2.6.2 Covariates ..........................................................................................25 v Page CHAPTER 3. RESULTS AND DISCUSSIONS ....................................................... 28 3.1 Profile descriptions ..................................................................................................... 28 3.2 Soil Physical Properties .............................................................................................. 30 3.2.1 Particle size distribution ....................................................................30 3.2.2 Bulk density ......................................................................................31 3.3 Soil Chemical Properties............................................................................................. 34 3.3.1 Base Saturation..................................................................................36 3.3.2 Organic matter ...................................................................................39 3.3.3 Potassium (K), Magnesium (Mg), and Calcium (Ca) .......................41 3.3.4 Effective Cation Exchange Capacity (ECEC)...................................43 3.3.5 Phosphorus ........................................................................................44 3.3.6 Exchangeable Al and Soil pH ...........................................................45 3.4 X-ray Diffraction ........................................................................................................ 46 3.5 Soil Map Units ............................................................................................................ 53 CHAPTER 4. CONCLUSIONS ................................................................................. 58 BIBLIOGRAPHY ............................................................................................................. 61 APPENDICES Appendix A. Initial Reconnaissance Survey .................................................................... 70 Appendix B: Profiles Described and Sampled from Pits .................................................. 72 Appendix C: Transect with Descriptions from Auger Borings ....................................... 82 Appendix D. Descriptive analysis (Tukey’s Test) ........................................................... 93 vi LIST OF TABLES Table .............................................................................................................................. Page Table 2.1 Altitude, physiographic description, and geology of the sampling sites. ......... 19 Table 2.2 Reclassed geomorphons .................................................................................... 26 Table 2.3 Landforms and classes used to produce soil class map .................................... 26 Table 3.1 Particle size distribution, textural class and bulk density for the 5 pedons. ..... 33 Table 3.2 Regression analysis showing relationship between bulk density and O.M ...... 33 Table 3.3 Chemical properties for the 5 sampled pedons. ................................................ 35 Table 3.4 Correlation coefficients (R) .............................................................................. 37 Table 3.5 Soil organic carbon present in a depth of 1 m-3 ................................................ 40 Table 3.6 criteria for levels of exchangeable cations (cmol(+)kg-1) ................................. 43 Table 3.7 Clay minerals present in the soil samples ........................................................ 46 vii LIST OF FIGURES Figure Page Figure 2.1 Map of Kenya showing the location of the study ........................................... 16 Figure 2.2 Location of the sampling points KN12 – KN16 and auger borings. .............. 18 Figure 2.3 The topography of the Uasin Gishu Plateau . .................................................. 20 Figure 2.4 Environmental variables. ................................................................................. 27 Figure 3.1 Profile photos of the pedons ............................................................................ 29 Figure 3.2 Ternary plot of textural composition ............................................................... 32 Figure 3.3 Base saturation, organic matter, phosphorus, and CEC distribution ............... 37 Figure 3.4 Basic cations, exchangeable aluminum and soil pH distribution. ................... 38 Figure 3.5 X-ray diffraction patterns of KN13C. ............................................................ 49 Figure 3.6 X-ray diffraction patterns of of KN15. ............................................................ 50 Figure 3.7 X-ray diffraction patterns of KN12C. ............................................................ 51 Figure 3.8 X-ray diffraction patterns of KN16B. ............................................................. 52 Figure 3.9 Soil Class Map . ............................................................................................... 56 Figure 3.10