| Abbreviations | 第9-10页 |
| Abstract | 第10-12页 |
| 摘要 | 第13-16页 |
| 1 Introduction | 第16-32页 |
| 1.1 Background and rationale | 第16-19页 |
| 1.2 Soil organic carbon and crop rotation system | 第19-21页 |
| 1.3 Effects of straw returning on SOC and soil properties | 第21-23页 |
| 1.4 Effect of straw returning on SOC characteristics and chemical composition | 第23-26页 |
| 1.5 Effect of straw returning and no-tillage on water stable aggregates | 第26-28页 |
| 1.6 Effect of straw returning and no-tillage on SOC of soil aggregates | 第28-29页 |
| 1.7 Purposes of the study | 第29-32页 |
| 2 Materials and methods | 第32-45页 |
| 2.1 Description of experimental sites and design | 第32-37页 |
| 2.1.1 Wuxue site | 第32-33页 |
| 2.1.2 Jingzhou site | 第33-34页 |
| 2.1.3 Whan site | 第34-37页 |
| 2.2 Crop management | 第37-38页 |
| 2.3 Soil sampling | 第38-39页 |
| 2.4 Water-stable aggregate separation and determination | 第39-40页 |
| 2.5 Analytical methods and calculations | 第40-44页 |
| 2.5.1 Initial soil characterization | 第40-41页 |
| 2.5.2 Soil organic carbon and labile C fractions | 第41页 |
| 2.5.3 CPMAS ~(13)C NMR Spectra analysis | 第41-42页 |
| 2.5.4 Fourier-transform infrared (FTIR) spectroscopy analysis | 第42页 |
| 2.5.5 Carbon content analysis by SEM/EDX | 第42-43页 |
| 2.5.6 SOC stocks quantification | 第43页 |
| 2.5.7 Soil carbon management index (SCMI) | 第43-44页 |
| 2.6 Statistical analysis | 第44-45页 |
| 3 Results | 第45-93页 |
| 3.1 Effects of straw returning on SOC and labile C fractions | 第45-54页 |
| 3.1.1 Soil organic carbon (SOC) | 第45-46页 |
| 3.1.2 Microbial biomass carbon (MBC) | 第46-49页 |
| 3.1.3 Dissolved organic carbon (DOC) | 第49-51页 |
| 3.1.4 Particulate organic carbon (POC) | 第51-53页 |
| 3.1.5 Easily oxidizable carbon (EOC) | 第53-54页 |
| 3.2 Soil carbon management index (SCMI) | 第54-58页 |
| 3.3 Effects of straw returning on soil organic carbon stocks | 第58-61页 |
| 3.4 Effects of straw returning on chemical composition of SOC | 第61-67页 |
| 3.5 Water stable aggregates and their stability indices | 第67-73页 |
| 3.6 Effects of straw returning on SOC contents in aggregates | 第73-76页 |
| 3.7 Effect of straw returning on the structure of soil aggregates | 第76-80页 |
| 3.8 C content analysis by SEM/EDX | 第80-84页 |
| 3.9 Correlations of SOC with C fractions, aggregates and chemical composition | 第84-93页 |
| 3.9.1 Correlations among SOC, C fractions and SCMI | 第84-87页 |
| 3.9.2 Relationships of SOC with different soil aggregates | 第87-89页 |
| 3.9.3 Relationships among C fractions and chemical composition | 第89页 |
| 3.9.4 Relationships of aggregates with chemical composition of SOC | 第89-93页 |
| 4 Discussion | 第93-104页 |
| 4.1 Effect of straw returning on SOC contents and stocks | 第93-94页 |
| 4.2 Effect of straw returning on SOC organic C fractions | 第94-96页 |
| 4.3 Effect of straw returning on soil carbon management index (SCMI) | 第96-97页 |
| 4.4 Effect of straw returning on chemical composition of SOC | 第97-99页 |
| 4.5 Relationship among SOC, C fractions and chemical composition | 第99-100页 |
| 4.6 Effects of straw returning on soil water stable aggregates | 第100-102页 |
| 4.7 Relationship between soil organic carbon and soil aggregates | 第102-104页 |
| 5 Conclusion and novelty of study | 第104-106页 |
| 5.1 Conclusion | 第104-106页 |
| 5.2 Novelty of study | 第106页 |
| 6 Future perspectives | 第106-107页 |
| 7 Publications | 第107-109页 |
| 7.1 Papers and Abstracts relating to this work | 第107页 |
| 7.2 Other papers | 第107-109页 |
| References | 第109-123页 |
| Acknowledgements | 第123-125页 |
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