1. Introduction and Review of Literature
1.1 Research Background
1.2 Review of Literature
1.2.1 Soil organic carbon and sequestration rate
1.2.2 Agriculture and GHG emissions
1.3 Summary
2. Research Contents and Ideas
2.1 Background
2.2 Research Contents
2.3 Technical route
3. Effects of Long-term Straw Return on Soil Organic Carbon Storage and Sequestration Rate in North China Upland Crops: a Meta-analysis
3.1 Introduction
3.2 Materials and Methods
3.2.1 Data collection
3.2.2 Data analysis
3.2.3 Meta-analysis
3.2.4 Statistical analysis
3.3 Results
3.3.1 Crop yields in different cropping systems
3.3.2 Response ratios of SOC stocks under different fertilizer treatments
3.3.3 Response ratios of SOC stocks in different soil types
3.3.4 SOC stock response in different cropping systems
3.3.5 Effect of experiment durations on SOC stocks
3.3.6 Relationships between SOC sequestration rates and annual C inputs from straw
3.4 Discussion
3.4.1 Straw and fertilizer management effects on SOC stocks
3.4.2 Response ratios of SOC stocks in different soil types
3.4.3 Crop rotation systems, SOC stocks, and crop yields
3.4.4 SOC stock responses and experimental durations
3.5 Summary
4. Effect of Different Long-term Straw Return Modes on Soil Organic Carbon Contents and Carbon Footprint in Annual Wheat–Maize Rotation System
4.1 Introduction
4.2 Materials and Methods
4.2.1 Study site
4.2.2 Experimental design
4.2.3 Data collection
4.2.4 Measurement of crop biomass and yield and estimation of cumulative plant-derved carbon input
4.2.5 Soil organic carbon storage and sequestration rate
4.2.6 Calculation of CFP and the system boundary
4.2.7 Statistical analysis
4.3 Results
4.3.1 Plant-derived C input, ΔSOC, and SOC sequestration rate
4.3.2 GHG emissions from different agricultural inputs
4.3.3 Effects of different long-term straw-return modes on grain yield and CFP
4.4 Discussion
4.4.1 SOC sequestration potential of different straw-return modes
4.4.2 Effect of straw return management and seasonal differences on GHG emissions
4.4.3 Crop yield and carbon footprint
4.4.4 Implications of different straw management strategies at the regional scale
4.5 Summary
5. Long-term Effect of Different Nitrogen Fertilizer Rates on Soil Organic Carbon Storage and Carbon Footprint in Annual Wheat–Maize Rotation System
5.1 Introduction
5.2 Materials and Methods
5.2.1 Study site
5.2.2 Experimental design
5.2.3 Data collection
5.2.4 Crop biomass, yield measurement and cumulative plant-derived carbon input estimation
5.2.5 Soil organic carbon stock and sequestration rate
5.2.6 Calculation of carbon footprint and the system boundary
5.2.7 Statistical analysis
5.3 Results
5.3.1 Plant-derived C input and SOC change
5.3.2 GHG emissions from different N-fertilizer rates
5.3.3 Effect of different N-fertilizer rates on grain yield and CFP
5.4 Discussion
5.4.1 N input rate and SOC sequestration potential
5.4.2 N fertilizer contribution on GHGs emission
5.4.3 N fertilizer effect on grain yield and CFP
5.5 Summary
6. Comprehensive Discussions, Main Conclusions, Innovations and Research Perspectives
6.1 Comprehensive discussions
6.2 Main conclusions
6.3 Innovative points of the study
6.4 Study perspectives
参考文献
Appendices
致谢
Self-introduction (简介)
西北农林科技大学;
