DIVERSITY AND ABUNDANCE OF DUNG BEETLES ACROSS DIFFERENT LAND USE TYPES AND THEIR ROLE IN SOIL FERTILITY IMPROVEMENT IN KENYA HARRISON WARUI CHURU A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF MASTER OF SCIENCE IN SOIL SCIENCE DEPARTMENT OF LAND RESOURCE MANAGEMENT AND AGRICULTURAL TECHNOLOGY FACULTY OF AGRICULTURE UNIVERSITY OF NAIROBI 2019 DECLARATION i DEDICATION I dedicate this work to my late Dad, Charles Gachunu. Your advice and prayers shaped my academic life. May your soul rest in eternal peace. ii ACKNOWLEDGEMENT I am greatly indebted to my supervisors Dr. Fredrick O. Ayuke, Prof. Nancy Karanja and Dr. Kenneth O. Odhiambo who have tirelessly walked with me through this academic journey. Your inputs, guidance, encouragements and at times scolding cannot be taken for granted. This research could not be complete without the help of technical staff. I most sincerely thank John Kimotho and Ferdinand Anyika from Department of Land and Resource Management in Agricultural Technology (LARMAT), Solomon Kamau, Reuben Mwakodi from Kenya Museum, Robinson Ouko from Kabete Meteorological station, Francis Gikonyo, Brian Machote and all those who helped out in data collection. Your assistance and dedication moved me. Finally, I greatly appreciate the Netherlands Initiative for Capacity Building in Higher Education (NICHE-UoE) Project for funding this research work. I am greatly indebted to Prof. Julius Ochuodho, Dr. Abigail Otinga and Prof. Wilson Ngetich who trusted and believed in me. To my wife Rose and entire family, I appreciate your tireless support and prayers. God Almighty bless you all abundantly. To Him be the Glory. iii TABLE OF CONTENTS DECLARATION................................................................................................... i DEDICATION ...................................................................................................... i ACKNOWLEDGEMENT .................................................................................... iii TABLE OF CONTENTS ...................................................................................... iv LIST OF TABLES ............................................................................................. viii LIST OF FIGURES .............................................................................................. x LIST OF PLATES ............................................................................................... xi APPENDICES .................................................................................................... xii LIST OF ABBREVIATIONS ............................................................................... xiii ABSTRACT ...................................................................................................... xiv CHAPTER ONE .................................................................................................. 1 1.0 INTRODUCTION ........................................................................................... 1 1.1 Background information .................................................................................................. 1 1.2 Statement of the problem and justification of study ........................................................ 2 1.3 Broad objective ................................................................................................................ 3 1.4 Specific objectives............................................................................................................ 3 1.5 Hypotheses ....................................................................................................................... 4 CHAPTER TWO ................................................................................................. 5 2.0 LITERATURE REVIEW ................................................................................... 5 2.1 Soil macrofauna diversity and their roles in ecosystem services ..................................... 5 2.2 Ecology of dung beetles ................................................................................................... 7 2.3 Factors influencing diversity and abundance of dung beetles .......................................... 8 2.4 Ecosystem functions and services of dung beetles ......................................................... 10 iv 2.4.1 Quantification of the roles of dung beetles in nutrients cycling, dung removal and decomposition ................................................................................................................... 13 2.5 Characterization of soils and animal dung ..................................................................... 14 2.6 Opportunities for utilization of dung beetles.................................................................. 14 2.7 Other macrofauna colonizing animal dung .................................................................... 15 2.8 Protocol for sampling dung beetles ................................................................................ 15 2.9 Existing information gaps in dung beetles studies ......................................................... 17 CHAPTER THREE ............................................................................................ 19 3.0 MATERIALS AND METHODS ....................................................................... 19 3.1 Description of the study site ........................................................................................... 19 3.2 Study designs and data collection .................................................................................. 21 3.2.1 Monolith sampling protocol .................................................................................... 22 3.2.2 Pitfall traps ............................................................................................................... 22 3.2.3 Terrarium experiment .............................................................................................. 24 3.2.4 Treatments, coding and experimental designs ......................................................... 24 3.3 Data collection................................................................................................................ 26 3.4 Laboratory analysis of soil and dung ball samples ........................................................ 28 3.5 Data analysis .................................................................................................................. 30 CHAPTER FOUR .............................................................................................. 32 4.0 RESULTS ..................................................................................................... 32 4.1 soil chemical properties and macrofauna abundance across land use types .................. 32 4.1.0 Soil chemical properties across land use types ........................................................ 32 4.1.1 Effect of LUTs on abundance of soil macrofauna in Kabete and Chepkoilel soils . 33 4.1.2 Correlation of macrofauna abundance with soil chemical properties in Kabete and Chepkoilel soils ................................................................................................................ 35 v 4.2 Species abundance and distribution of dung beetles in Kabete and Chepkoilel soils .... 36 4.2.1 Abundance of dung beetles in Kabete soils as influenced by land use types and seasonality ........................................................................................................................ 41 4.2.2 Effect of land use types and seasons on the abundance of dung beetles in Chepkoilel soils ................................................................................................................ 42 4.2.3 Effect of seasonality and land use types on dung beetle diversity in Kabete soils .. 42 4.2.4 Effect of LUTs and season on dung beetle species richness and diversity in Chepkoilel soils ................................................................................................................ 44 4.2.5 Correlation coefficient of abundance, richness and diversity of dung beetles with rainfall and air temperature ............................................................................................... 46 4.3 Effect of selected dung beetle species and type of animal fecal material on the amount and rate of dung removal ...................................................................................................... 46 4.3.1 Effect of selected dung beetle species and type of animal fecal material on nutrients content of buried dung balls ............................................................................................. 47 CHAPTER FIVE ............................................................................................... 50 5.0 DISCUSSION ................................................................................................ 50 5.1 Abundance of soil macrofauna and their correlation with soil chemical properties ...... 50 5.1.1 Influence of land use types on abundance of soil macrofauna in Kabete and Chepkoilel soils ................................................................................................................ 50 5.1.2 Correlation between the abundance of soil macrofauna with soil chemical properties .......................................................................................................................... 51 5.2 Influence of land use types and seasonality on abundance and