Chapter �� Soil structure and soil organic carbon in dryland farming 1.1 Soil structure 1.2 Soil structural stability 1.3 Soil organic carbon 1.4 S0C status in agroecosystem 1.5 Processes controlling S0C sequestration 1.6 The effect of tillage management on soil structure and S0C 1.7 The effect of long-term applications of organic materials on soil structure and SOC 1.8 The Loess Plateau of China Reference Chapter �� The effect of conservation tillage on grain yield by changing soil hydraulic properties and soil water availability 2.1 Overview of the study area and experimental design 2.2 Experimental indicator and statistical analysis 2.3 Is least limiting water range a useful indicator of the impact of tillage management on maize yield 2.4 Factors governing soil water repellency under tillage management: the role of pore structure and hydrophobic substances 2.5 Does soil water repellency reduce corn yield by changing soil water availability under long-term tillage management References Chapter �� The effect of conservation tillage on organic carbon and microbial properties 3.1 Overview of the study area and experimental design 3.2 Experimental indicator and statistical analysis 3.3 A meta-analysis of no-tillage impacts on soil aggregation and aggregate-associated organic carbon 3.4 Linking soil microbial keystone taxa and SOC accumulation under long-term conservation tillage practices 3.5 Nitrogen addition mediates the effect of microbial properties on soil microbial CUE under long-term tillage practices References Chapter IV Effect of long-term conservation tillage practices on soil structure and soil organic carbon dynamic in the Loess Plateau of China 4.1 Overview of the study area and experimental design 4.2 Experimental indicator and statistical analysis 4.3 Soil wet aggregate distribution and pore size distribution under different tillage systems after 16 years in the Loess Plateau of China 4.4 Effect of different tillage systems on aggregate structure and inner distribution of organic carbon 4.5 Effects of different long-term tillage systems on the composition of organic matter by 13C CP/TOSS NMR in physical fractions in the Loess Plateau of China References Chapter V The effect of organic materials on soil physical properties and organic carbon in dryland 5.1 Overview of the study area and experimental design 5.2 Measurements 5.3 Effects of long-term application of different organic materials on the structure and organic carbon of soil aggregates 5.4 Quantity and quality of organic matter in their relation to soil pore system allocation induced by long-ter m organic materials application in dryland 5.5 Long-term application of organic wastes improves soil carbon and structural properties in dryland affected by coal mining activity References Chapter VI The effect of organic amendment on soil organic carbon by changing soil microbial characteristics 6.1 Overview of the study area and experimental design 6.2 Experimental indicator and statistical analysis 6.3 The contribution of microorganisms to soil organic carbon stock under fertilization varies among aggregate size classes 6.4 The dominant microorganisms vary with aggregates sizes in promoting soil C accumulation under straw application References Attachments