| 摘要 | 第4-6页 |
| Abstract | 第6-7页 |
| List of abbreviations | 第15-16页 |
| 1 INTRODUCTION 1 | 第16-19页 |
| 1.1 Background | 第16-18页 |
| 1.2 Objectives of the Study | 第18页 |
| 1.3 Hypotheses to be tested | 第18页 |
| 1.4 Research questions | 第18-19页 |
| 2 LITERATURE REVIEW 4 | 第19-33页 |
| 2.1 Outline of soils organic carbon researches in South Africa | 第19-20页 |
| 2.2 Soil SOC and humic substances studies international | 第20-29页 |
| 2.2.1 Soil organic matter | 第20-23页 |
| 2.2.1.1 The importance of Soil Organic Matter (SOM) in soil | 第20-21页 |
| 2.2.1.2 Contributors to soil organic matter (SOM) formation | 第21-22页 |
| 2.2.1.3 The decomposition of soil organic matter (SOM) | 第22-23页 |
| 2.2.2 Importance of Humus in soil | 第23-27页 |
| 2.2.2.1 Humus effect on microbial and enzyme actions | 第25-26页 |
| 2.2.2.2 Humus effect on plant growth | 第26页 |
| 2.2.2.3 Humus effect on nutrient uptake | 第26-27页 |
| 2.2.3 Techniques of studying soil organic matter | 第27-29页 |
| 2.2.3.1 Degraded method of humic substances analysis | 第27-28页 |
| 2.2.3.2 Non-degraded methods of humic substances analysis | 第28-29页 |
| 2.3 Land use and management effects on soil organic matter | 第29-32页 |
| 2.3.1 Land use practices | 第29-30页 |
| 2.3.2 Land management practices | 第30-32页 |
| 2.4 Purpose and significance of the study | 第32-33页 |
| 3 MATERIALS AND METHODS 18 | 第33-40页 |
| 3.1 Site description | 第33-36页 |
| 3.1.1 Soils from South Africa | 第33-35页 |
| 3.1.1.1 Site information | 第33-34页 |
| 3.1.1.2 Soil Sampling | 第34-35页 |
| 3.1.2 Soils from China | 第35-36页 |
| 3.1.2.1 Site information | 第35页 |
| 3.1.2.2 Soil Sampling | 第35-36页 |
| 3.2 Soil Analysis | 第36-39页 |
| 3.2.1 Determination of basic properties of soil | 第36-37页 |
| 3.2.2 Humus extracts component | 第37-38页 |
| 3.2.3 Humic substances structural characterization | 第38-39页 |
| 3.2.3.1 Optical properties (ΔlogK) | 第38页 |
| 3.2.3.2 Elemental composition analysis (elemental analysis) | 第38页 |
| 3.2.3.3 Infrared spectroscopy (IR) | 第38-39页 |
| 3.3 Data analysis | 第39-40页 |
| 4 RESULTS 25 | 第40-68页 |
| 4.1 Soils from South Africa | 第40-54页 |
| 4.1.1 Land use and soil type effects on selected soil properties | 第40-43页 |
| 4.1.1.1 Soil type effects on selected soil properties | 第40-42页 |
| 4.1.1.2 Land use effects on selected soil properties | 第42-43页 |
| 4.1.2 Land use and soil type effects on SOC | 第43-44页 |
| 4.1.2.1 Soil type effects on SOC content of the soil | 第43页 |
| 4.1.2.2 Land use effects on SOC content of black soils | 第43-44页 |
| 4.1.3 Land use and soil type effects on soil humus composition | 第44-48页 |
| 4.1.3.1 Soil type effects on soil humus composition | 第44-45页 |
| 4.1.3.2 Land use effects on humus composition of black soils | 第45-46页 |
| 4.1.3.3 The PQ value (%) of varying land use and soil types | 第46-48页 |
| 4.1.4 Land use and soil type effects on soil structural characteristics of HA and FA | 第48-54页 |
| 4.1.4.1 Structural characteristics of varied with soil types | 第48-50页 |
| 4.1.4.2 Land use effects on structural characteristics of black soil | 第50-54页 |
| 4.2 Soils from China | 第54-63页 |
| 4.2.1 Land use and corn stover incorporation effects on selected properties of black soils | 第54-56页 |
| 4.2.1.1 Land use effects on selected properties of black soil | 第54-55页 |
| 4.2.1.2 Corn stover incorporation effects on selected properties of black soil | 第55-56页 |
| 4.2.2 Land use and corn stover incorporation effects on organic carbon soils of black | 第56-57页 |
| 4.2.2.1 Land use effect on the soil organic carbon (SOC) | 第56-57页 |
| 4.2.2.2 Corn stover incorporation effects on soil organic carbon (SOC) | 第57页 |
| 4.2.3 Land use and corn stover incorporation on humus composition (HA、FA、Hu、PQ) | 第57-60页 |
| 4.2.3.1 Land use effects on humus composition | 第57-58页 |
| 4.2.3.2 Corn stover incorporation effects on humus composition | 第58页 |
| 4.2.3.3 Land use and corn stover incorporation effect on PQ value | 第58-60页 |
| 4.2.4 Land use and deep incorporation of corn stover effects on soil structural characteristics of HA and FA | 第60-63页 |
| 4.2.4.1 Land use effects on structural characteristics of HA | 第60-63页 |
| 4.3 Comparisons of chemical properties and humic substances in black soils from South Africa and China | 第63-68页 |
| 4.3.1 Cultivated soils | 第63-65页 |
| 4.3.1.1 Comparisons of selected properties of black cultivated soils from two regions | 第63页 |
| 4.3.1.2 Comparisons of humus fractions of black cultivated soils from two regions | 第63-64页 |
| 4.3.1.3 Comparisons of humus structural characteristics black cultivated soils from two regions | 第64-65页 |
| 4.3.2 Grassland soils | 第65-68页 |
| 4.3.2.1 Comparisons of selected properties black grassland soils from two regions | 第65-66页 |
| 4.3.2.2 Comparison of humus fractions black cultivated soils from two regions | 第66-67页 |
| 4.3.2.3 Comparison of humus structural characteristics black cultivated soils from two regions | 第67-68页 |
| 5 DISCUSSIONS 53 | 第68-81页 |
| 5.1 Land use and soil type effects on chemical properties and humic substances soils from South Africa | 第68-75页 |
| 5.2 Land use and stover incorporation effects on chemical properties and humic substances on black soils from China | 第75-78页 |
| 5.3 Comparisons of chemical properties and humic substances in black soils from South Africa and China | 第78-81页 |
| 6 CONCLUSION AND RECOMMENDATIONS | 第81-83页 |
| REFERENCES | 第83-99页 |
| 作者简介 | 第99-100页 |
| ACKNOWLEDGEMENTS | 第100页 |
