Mesofaunal Assemblages in Soils of Selected Crops Under Diverse Cultivation Practices in Central South Africa, with Notes on Collembola Occurrence and Interactions
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MESOFAUNAL ASSEMBLAGES IN SOILS OF SELECTED CROPS UNDER DIVERSE CULTIVATION PRACTICES IN CENTRAL SOUTH AFRICA, WITH NOTES ON COLLEMBOLA OCCURRENCE AND INTERACTIONS by Hannelene Badenhorst Submitted in fulfilment of the requirements for the degree Magister Scientiae in Entomology Department of Zoology and Entomology Faculty of Natural and Agricultural Sciences University of the Free State Bloemfontein South Africa 2016 Supervisor: Prof. S.vd M. Louw “We know more about the movement of celestial bodies than about the soil underfoot” ~ Leonardo da Vinci (1452 – 1519) i Acknowledgements I extend my sincere gratitude to the following persons and institutions for their contributions towards this study: o Prof. S.vd M. Louw for his guidance and assistance in the identification of Coleoptera. o Dr. Charles Haddad (University of the Free State) for his assistance with identification of the Araneae. o Dr. Lizel Hugo Coetzee and Dr. Louise Coetzee (National Museum, Bloemfontein) for the identification of the Oribatida. o Dr. Pieter Theron (North-West Unniversity) for the identification of mites. o Dr. Charlene Janion-Scheepers (Monash University) for her assistance with the identification of the Collembola. o Dr. Vaughn Swart for the identification of the Diptera. o Mr. N.J. van der Schyff (Onmia, Kimberley) for his assistance in the interpretation of soil chemical analyses. o The farmers (G.F.R. Nel, W.J. Nel, J.A. Badenhorst, H.C. Kriel & Insig Ontwikkelingsvennootskap) that allowed us to conduct research on their farms and for their full cooperation in regards to information on the applied practices. o Jehane Smith for her motivation, friendship and assistance on field trips. o Deidré West for her friendship and encouragement throughout this study. o Esther Badenhorst, Ian Cloete and Jolene Coertzen for their friendship and for assisting in the final proofing. o My parents, André and Esther Badenhorst, for financial support and for their ever loving support and encouragement throughout this study. o My grandparents, Felie and Hanna Nel, for their encouragement and support. o The rest of my family and friends for their support throughout my studies. o Personnel, colleagues and friends at the Department of Zoology and Entomology for their support, encouragement and guidance, especially Dr. Candice, Isabel and Prof. Linda. o Thank you Lord for taking me on this journey and seeing it through. ‘I can do all things through Christ who strengthens me’ Phil. 4:13 ii TABLE OF CONTENTS ABSTRACT…………………………………………………………………………………vi UITTREKSEL…...…………………………………………………………………………viii CHAPTER 1: OVERVIEW OF THE IMPORTANCE OF SOIL FAUNA IN AGRO- ECOSYSTEMS AND THE FACTORS THAT INFLUENCE THEIR DIVERSITY…….1 a) Biotic component of soil………………………………………………………………….4 i) Spatial scales of biotic interactions……………………………………………5 ii) Soil biota (excluding higher plants)……………………………………………9 Bacteria……………………………………………………………………….…11 Fungi……………………………………………………………………………..11 Soil fauna…………………………………………..……………………………12 iii) Ecosystem services……………………………………………………………...23 Decomposition……………………………….………………………………...24 Nutrient cycling………………………………………………………………...24 Ecosystem engineering………………………….…………………………...25 b) Abiotic component of soil……………………………………………..………………...26 i) Soil types………………………………………………………………………..…26 Soil structure…………………………………………..………………….……26 Chemical composition…………………………………………………..……28 ii) Environmental influences………………………………………………………29 Climate (humidity and temperature)…………………………..……………29 c) Agricultural practices…………………………………………………………….………30 i) Crop and natural vegetation……………………………………………………31 ii) Physical / mechanical disturbances…………………………………………..33 Conventional tillage vs no-tillage systems………………………..………33 Controlled stubble-burning……………………………………………..……34 Field management……………………………………………………….…….35 iii) Pests and diseases………………………………………………..………..……36 iv) Chemical applications…………………………………………………...………38 d) Aim of the study……………………………………………………………………...……39 e) References…………………………………………………………………….……………40 iii CHAPTER 2: SAMPLING PROCEDURES AND DATA ANALYSIS…………….……57 a) Sampling procedure………………………………………………………………………57 i) Field sampling…………………………………………….………………………57 ii) Laboratory extraction, sorting and identification……………..……………59 Laboratory extraction…………………………………………………………59 Sorting during preliminary study (2011-2012)……………………………60 Sorting during primary study (2012-2014)…………...……………………61 Identification……………………………………………………………………62 iii) Trophic level analysis……………………………………………………………63 b) Statistical analysis……………………………………………………………..…………64 i) Shannon’s diversity and evenness index……………………………………64 ii) Bray-Curtis dissimilarity measure……………………………….……………66 c) References…………………………………………………………………………….……67 CHAPTER 3: STUDY SITES AND AGRICULTURAL APPLICATIONS…………..…69 a) Site descriptions and relevant observations…………………………………………69 i) Locality 1: Vaaldam farm………………………………………………….……70 ii) Locality 2: Koppieskraal farm…………………………………………………76 iii) Locality 3: Thornberry farm……………………………………………………79 iv) Locality 4: Paradys farm……………………………………………..…………83 v) Locality 5: Eureka farm…………………………………………………………87 vi) Locality 6: Klein Brittanje………………………………………………………94 vii) Agricultural disturbances………………………………………...……………100 b) References……………………………………………………………………………...…103 CHAPTER 4: SOIL MESOFAUNA RECORDED IN DIFFERENT AGRICULTURAL LANDSCAPES………………………………………………………………...…………………105 a) Environmental influences………………………………………………………………106 i) Soil organismal diversity in the porospheres of different plants………106 ii) Variation in soil organism diversity at different clay percentages….…111 iii) Diversity differences within a maize field on a topographical gradient……………………………………………………………………………119 b) Anthropogenic influences…………………………………………………………...…123 i) Influence of controlled stubble-burning and its alternative on mesofaunal diversity……………………………………………………………123 iv ii) Effect of mechanical disturbance in fields…………………………………131 iii) Mesofaunal diversity relative to conversion of natural veldt to maize field………………………………………………………………………………...133 iv) Soil organism diversity in fallow fields vs planted fields…………..……136 c) Conclusion…………………………………………………………………………..……141 d) References……………………………………………………………………..…………144 CHAPTER 5: POLLUTANTS, PESTICIDES AND AGRICULTURE – THE EFFECTS ON SOIL FAUNAL GROUPS AND HOW COLLEMBOLA FITS IN……147 a) Grassland pollution by a gold mine tailings dam……………………………….…148 i) Sampling points at spillage sites………………………………………….…149 ii) Sampling points as control (away from spillage sites) ………………….153 b) Pesticides in a grassland…………………………………………………………….…154 c) Collembolan incidence and observations……………………………………..……157 i) Koffiefontein district……………………………………………………………158 ii) Jacobsdal district…………………………………………………………….…162 iii) Bloemfontein district………………………………………………...…………167 iv) Odendaalsrus district…………………………………………..………………171 v) Bothaville district……………………………………………..…………………174 d) Conclusion…………………………………………………………………..……………178 e) References………………………………………………………………………………...180 CHAPTER 6: GENERAL CONCLUSION, RECOMMENDATIONS & FUTURE RESEARCH……………………………………………………………………………………….184 a) General conclusion……………………………………………………………………...184 b) Recommendations…………………………………………………………………….…188 c) Future research………………………………………………………………..…………189 i) Polluted sites………………………………………………………………….…189 ii) Pesticide application sites…………………………….………………………190 iii) Different fertilizer application methods……………………………..………190 iv) Sandstorms: Distribution due to ‘air borne’ topsoil………………..……191 v) Survey of South African Collembola……………………………………...…191 d) References…………………………………………………………………………...……192 ADDENDUM A……………………………………………………………………………………193 ADDENDUM B……………………………………………………………………………………208 v ABSTRACT Soil is a complex medium, comprised of both biotic and abiotic components. Interactions between these components are responsible for the beneficial services provided within different ecosystems. The biotic component, which is also referred to as the active role players in the soil, is responsible for these services. The incidence of these organisms is influenced by the abiotic factors, which act as filtering mechanisms that select for certain species to occur within certain areas. Considering an ever-increasing human population, these services could prove beneficial, since it could improve crop yields at minimal cost without exploiting the soil resource. Many farmers are now changing their farming methods to more sustainable and conservation focused practices to try and reduce the disruption of soil community structures and to optimize the complexity and resilience of these communities. Disturbances lower the complexity of soil communities and therefore limit the services that could be provided. This study focused on the fluctuations in diversity of selected role players within the soil medium due to the presence of certain agricultural practices and environmental changes. Sampling for this project was conducted at six localities in the Free State Province between 2011 and 2014. Three of the localities are located in the Nama Karoo Biome and the other three in the Grassland Biome. The farms Vaaldam, Koppieskraal, Thornberry and Klein Brittanje were selected due to the diversity of agricultural practices and management strategies applied. The rest of the localities were the Paradys Experimental Farm, which is the experimental farm of the University of the Free State, where a pesticide trial was conducted and the farm Eureka, which was exposed to pollutants from a goldmine tailings dam. The variation in events