Preface 9
Introduction 10
Soils: integral part of our environment 10
Soil characteristics  11
1 Grain size distribution: texture 13
1.1 Classification 13
1.1.1 Grain sizes  14
1.1.2 Grain shapes 16
1.1.3 Grain mixtures  17
1.2 Common soil textures and their origin  21
1.2.1 Equation of sedimentation  22
1.2.2 Separation processes  23
1.3 Spatial distribution of textures 25
1.4 Modification of grain size distributions in soils 26
1.5 Grain size distribution and other soil properties 27
1.6 Methods to measure grain size distributions  30
Problems Chapter 1  31
2 Soil structure and structural functions 33
2.1 Soil structure and internal morphology  33
2.2 Bulk density, particle density  35
2.3 Pore volume and void ratio  36
2.3.1 Theoretical quantities to describe pore volumes 37
2.3.1.1 Influence of grain size and shape on pore volume  37
2.3.1.2 Effect of particle size  38
2.3.2 Number of grain contacts 39
2.3.2.1 Relationship of contact number and pore volume fraction 40
2.3.2.2 Natural grain size distributions and aggregates 41
2.3.3 Influence of grain contact points on soil pedogenesis 41
2.4 Pore size distributions  44
2.4.1 Subdividing pore sizes  44
2.4.2 Shapes, sizes of pores, and modes of pore formation 47
2.4.3 Effects of pore size distribution on soil quality 48
Problems Chapter 2  48
3 Mechanical and hydraulic forces in soils 50
3.1 Stability and the spatial arrangement of grains  50
3.1.1 Forces and stresses in soils  50
3.1.2 Subdivision of the forces and stresses within soils  54
3.1.2.1 Particle weight  55
3.1.2.2 Loads transmitted by solid phases of soils 55
3.1.2.3 Weight (overburden) stresses transmitted within the solid phase 55
3.1.2.4 Forces between the surfaces of adjacent particles  56
3.1.3 Stresses in three-dimensional space 56
3.2 Soil strength: the balance of forces  57
3.2.1 Shear resistance, a soil property  57
3.2.1.1 Shear resistance of soils and their determination 57
3.3 Stress strain relationship and time-dependent settlement  63
3.3.1 Stress strain relationship in soils  63
3.3.2 Time dependent settlement behavior of soils  65
3.3.3 The meaning of neutral stresses during loading 66
3.4 Stress-, strain-, and deformation processes in three-dimensional space.68
3.4.1 Stress and strain in three-dimensional space  68
3.4.2 Stress propagation within soils 68
3.4.3 Base failure as the result of the active and passive Rankine state 71
3.5 Flow behavior of soils: stresses between individual soil particles 74
3.6 Influence of soil properties on shear resistance 79
3.7 Mechanical changes of soil structure 79
3.7.1 Effects of anthropogenic activities on soils  79
3.7.2 Effects of animal activity and plant growth  81
3.7.3 Freezing effects  83
3.7.4 Soil compaction in civil engineering and construction 83
Problems Chapter 3  84
4 Interactions between water and soil 86
4.1 Adsorption of water in soils  86
4.1.1 Adsorption mechanisms 86
4.1.2 Properties of water adsorbed on soil components  88
4.2 Flocculation and peptization of soil particles  89
4.3 Shrinkage of soils  91
4.3.1 Causes of soil shrinkage 91
4.3.2 Shrinkage in soils  94
4.4 Swelling of soils  95
4.4.1 Mechanisms of swelling: swelling pressure  96
4.4.2 Inhibition of swelling  99
4.5 Cracking up: crack formation in soils  100
4.6 Water as a factor of soil stability  103
4.6.1 Static water pressure  103
4.6.2 Flow pressure in soils  105
4.7 Wetting properties of soils  107
4.7.1 Causes and occurrence of inhibited wetting of soil particle surfaces 107
4.7.2 Contact angles and capillarity 108
4.7.3 Documenting wetting properties  111
4.7.4 Impact of wetting properties on the environmental and habitat functions of soils 113
4.8 Electrical flow potentials in soils  114
4.9 Aggregate shapes and functions  115
4.9.1 Natural aggregate-forming processes  116
4.9.2 Anthropogenic modification of soil aggregates 120
4.10 Effects of aggregate size, - shape and -age 120
Problems Chapter 4  122
5 Distribution and hydrostatics of soil water 123
5.1 Distribution and origin of water in soils  123
5.2 Forces in soil water 124
5.3 The groundwater surface as reference plane  126
5.4 Soil water potential 127
5.4.1 Total water potential and component water potentials 128
5.4.1.1 Matric potential Ψm  129
5.4.1.2 Gravitational potential Ψz  129
5.4.1.3 Osmotic potential Ψo  130
5.4.1.4 Overburden or load potential ΨΩ  130
5.4.1.5 Pressure potential ΨP  131
5.4.2 Combining component potentials  131
5.4.3 Instruments for measuring soil water potentials 132
5.5 Equilibrium water potential  134
5.6 Relationship between matric potential and water content  135
5.6.1 Effect of grain size distribution on the matric potential/water content relationship137
5.6.2 Influence of structure on the shape of the matric potential/water content relationship 137
5.6.3 Hysteresis of the matric potential/water content curve  139
5.6.4 Measuring matric potential / water content curves  139
5.6.5 Mathematical description of the matric potential–water content relationship 141
Problems Chapter 5  141
6 Movement of water within the soil 143
6.1 Water movement in water saturated soil  143
6.1.1 Fluid-dynamic phenomena in soils  143
6.1.2 Flow Fields  147
6.1.3 Boundary conditions and spatial limits of flow fields 147
6.1.4 One-dimensional flow  148
6.1.5 Two- and three-dimensional flows  150
6.2 Water movement in unsaturated soil 153
6.3 Transient flow 155
6.3.1 Hydraulic diffusivity  159
6.4 Hydraulic conductivity as a soil property 160
6.5 Vapor transport  168
6.6 Infiltration  169
6.7 Drainage  174
6.8 Evaporation  181
Problems Chapter 6  188
7 The gas-phase of soils 193
7.1 The energetic state of the gas phase of soils  193
7.2 Composition of the gas phase in soils  195
7.3 Transport processes in the gas phase of soils  196
7.3.1 Gas diffusion 197
7.3.2 Mass fluxes in the gas phase of soils 199
7.3.3 Redistribution of gas within the soil 199
Problems Chapter 7  201
8 Thermal behaviour of soils 204
8.1 Thermal properties of soils  204
8.1.1 Definitions  204
8.1.2 Heat capacity of soils  205
8.1.3 Thermal conductivity  208
8.1.4 Thermal diffusivity 210
8.1.5 Mechanisms of heat transport in soils  211
8.2 Modeling thermal conductivity 213
8.3 Techniques for measuring thermal properties  213
8.4 Phase transitions of H2O and their effects 214
8.4.1 Redistribution of water vapor by thermal flux  214
8.4.2 Freezing and the formation of ice  215
8.4.3 Freezing and water movement 216
8.4.4 Formation of structure  218
Problems Chapter 8  219
9 Combined water-, heat and gas budget of soils 221
9.1 The atmosphere–soil interface 221
9.1.1 Radiation components and radiation budgets  221
9.1.2 Energy budget at the soil surface  224
9.2 Dynamics and temporal variations of the soil water budget 226
9.2.1 Ground- and floodwater 228
9.2.2 Path of matric potentials 231
9.2.3 Parameters characterizing water budgets  236
9.2.3.1 Field capacity  236
9.2.3.2 Permanent wilting point 239
9.3 Heat budget  239
9.3.1 Temperature distributions in soils  240
9.3.2 Heat sources 241
9.3.3 Soil temperature variations  241
9.3.4 Cumulative effects on the heat budget  245
9.4 Gas budget of soils 247
9.4.1 How water content affects gas distribution within the soil profile 248
9.4.2 Seasonal variations of soil air 250
Problems Chapter 9  252
10 Plant habitats and their physical modification 255
10.1 Plant requirements in terms of water supply  255
10.2 Interaction of mechanical and hydraulic processes  258
10.2.1 Mechanical and hydraulic soil deformation  259
10.2.2 Pore function changes resulting from mechanical and hydraulic stresses 261
10.2.3 Interactions between hydraulic pore function and mechanical parameters 264
10.2.4 Effects of soil management on physical parameters  264
10.3 Modification of the hydraulic stress state 266
10.3.1 Drainage  267
10.3.2 Irrigation  270
10.3.3 Percolation  272
10.4 Modification of the mechanical stress state  273
10.4.1 Compaction  273
10.4.2 Loosening soils  274
10.4.3 Material rearrangement  275
Problems Chapter 10 277
11 Soil erosion 280
11.1 Soil erosion: general principles  280
11.1.1 Delamination of particles or aggregates  281
11.2 Approaches to preventing erosion  285
11.2.1 Erodibility of soils 286
11.2.2 Erosivity of wind and water  287
11.3 Erosion models  287
11.3.1 Soil erosion by water  288
11.3.2 Soil erosion by wind  290
Problems Chapter 11 290
12 Solute transport and filter processes in soils 293
12.1 Solute transport: basics  294
12.1.1 Breakthrough curves in porous media  294
12.1.2 Molecular diffusion 296
12.1.3 Convective flux and hydrodynamic dispersion  298
12.1.4 Adsorption  299
12.1.5 Convection-dispersion model of solute transport in soils  300
12.1.6 Additional factors influencing solute transport  302
12.1.7 Models describing solute transport  303
12.2 Filtering processes in soils  304
12.2.1 Filter types  304
12.2.2 Soils acting as filters  305
12.2.3 Filter efficiency  306
12.2.4 Optimizing filtering processes 308
Problems Chapter 12 309
13 Future Perspectives of Soil Physics 311
Solutions to the problems of chapters 1–12 319
14 References 347Appendix15 Commonly used units and conversion factors 373Meaning of abbreviations 373
Basic conversions: density and pore volume  374
Transport  375
Derivation of the heat-budget equation  376
Energy Budget at the soil surface  377
Tensors  378
Conversion of units 379
Keyword Index 380