Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1993 Pedogenic Development of Soils at High Altitude in Burundi. Salvator Kaburungu Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Kaburungu, Salvator, "Pedogenic Development of Soils at High Altitude in Burundi." (1993). LSU Historical Dissertations and Theses. 5646. https://digitalcommons.lsu.edu/gradschool_disstheses/5646 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. 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Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. University Microfilms International A Bell & Howell Information Company 300 North Zeeb Road. Ann Arbor, Ml 48106-1346 USA 313/761-4700 800/521-0600 Order Number 9419900 Pedogenic development of soils at high altitude in Burundi Kaburungu, Salvator, Ph.D. The Louisiana State University and Agricultural and Mechanical Col., 1993 UMI 300 N. Zeeb Rd. Ann Arbor, M I 48106 PEDOGENIC DEVELOPMENT OF SOILS AT HIGH ALTITUDE IN BURUNDI A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mecanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Agronomy by Salvator Kaburungu B.S., University of Burundi, 1981 M.S., Louisiana State University, 1990 December 1993 ACKNOWLEDGMENTS I would like to express my sincere and deep appreciation to my major professor, Dr. Wayne Hudnall, for his continuous guidance, supervision and encouragement. I feel greatly honored to have worked with him on both my M.S. and Ph.D. programs. My gratitude is also extensive to the Hudnall’s family, Ms.(Callalya) Hudnall and son Eric for their friendship and support. I am sincerely grateful to my graduate committee , Dr. S. E. Feagley, Assoc. Professor, Dept, of Agronomy; Dr. J. S. Hanor, Professor, Dept, of Geology and Geophysics, Dr. W. H. Patrick, Jr., Boyd Professor, Wetland Biogeochemistry Institute, Dr. R. P. Gambrell, Professor, Wetland Biogeochemistry Institute, Dr. W. A. Young, Professor, Dept, of Horticulture, Mr. B. A. Touchet, SCS - State Soil Scientist; and Dr. F. Rhoton, USDA - ARS; for their education, guidance and time devoted to review this manuscript. I wish to express my sincere and deep appreciation to AAI/ATLAS for their financial support on both my graduate degrees without which I could not have undertaken the studies. A deep appreciation is also extended to Ms Michelle Roberts, my educational adviser, and her assistant, Ms Jackie Allen, for their continuous support. I would also like to express appreciation to Scott and Michelle Nesbit for their friendship which made my stay at Louisiana State University an enjoyable experience. Special thanks are extended to Xiaowei Zhang who, in spite of her hectic schedule, managed to help me with the typing of this manuscript while taking her Ph. D. general exams. Last but not the least, I am grateful to Mr. A. Gakoko, ISABU, Mr. A. Ndihokubwayo, ISABU and J.P. Muganza, ISABU, who kindly helped me to describe and collect soil samples. TABLE OF CONTENTS ACKNOWLEDGMENTS ............................................................................ ii ABSTRACT ................................................................................................. iv CHAPTER 1 PEDOGENIC DEVELOPMENT OF SOILS AT HIGH ALTITUDE IN BURUNDI: A LITERATURE REVIEW ..................................... 1 1.1. Introduction .............................................................................. 1 1.2. Rationale ................................................................................. 2 1.3. Brief Characterization and Classification of the Soils ............ 3 1.3.1. Soils under Natural Forest................................................ 3 1.3.2. Soils under Pasture ........................................................... 6 1.3.3. Evolution of Soils under Cultivation ................................. 14 1.3.3.1. Effects of Cultivation on Selected Soil Properties ..... 15 1.3.3.2. Effects of Cultivation on Organic Matter Content and Bulk Density .......................................................... 18 1.3.3.3. Effects of Cultivation on Soil Morphology and hydraulic Conductivity .................................................. 21 1.3.3.4. Effects of Cultivation on Both Surface and Subsurface Horizons ............................................ 21 1.3.4. Effects of Cultivation on Soils at High Altitude in Burundi ............................................................................ 22 2 EFFECTS OF LONG-TERM CULTIVATION AND PASTURE FOLLOWING DEFORESTATION........ .......................... 25 1.1. Introduction .............................................................................. 25 2.2. The Study A re a ....................................................................... 27 2.2.1. Background Information on Burundi ................................ 27 2.2.2. Location of the Study A re a .............................................. 30 2.2.3. Land U se .......................................................................... 30 2.2.4. Geological Setting ............................................................. 32 2.2.5. Clim ate .............................................................................. 33 2.3. Materials and Methods ........................................................... 33 2.3.1. Experimental Design and Field Methods ....................... 33 2.3.2. Laboratory Analysis .......................................................... 37 2.4. Results and Discussions ........................................................ 38 2.4.1. Morphological Comparisons ............................................. 38 2.4.2. General Chemical and Physical Comparisons ............... 41 3 MINERALOGICAL PROPERTIES AND AGGREGATE STABILITY .................................................... 57 3.1. Introduction ........................................................................... 57 iv 3.2. Materials and Methods ........................................................... 58 3.3. Results ...................................................................................... 58 3.4. Discussions ............................................................................. 62 4 GENESIS AND CLASSIFICATION OF HIGH-ALTITUDE SOILS IN BURUNDI....................................................... 78 4.1. Introduction .............................................................................. 78 4.2. Materials and Methods ........................................................... 80 4.2.1. Field Setting ...................................................................... 80 4.2.2. Laboratory Analyses .......................................................... 81 4.3. Results ..................................................................................... 82 4.3.1. Forest S o ils ....................................................................... 82 4.3.2. Culture S oils ...................................................................... 86 4.3.3. Pasture S o ils ..................................................................... 90 4.4. Discussions ............................................................................. 91 4.4.1. Genesis of High-Altitude Soils in Burundi ...................... 91 4.4.2. Evolution of the Soils Following Deforestation ............... 114 4.4.3. Classification of High Altitude Soils in Burundi .............. 115 5 SUMMARY AND CONCLUSIONS ................................................. 122 5.1. Summary ............................................................................ 122 5.2. Conclusions ........................................................................... 125 LITERATURE CITED................................................................................. 129 APPENDIX A ............................................................................................