1 Introduction: Objectives and Background ...................... 1
1.1 The Need to Understand the Plant - Earth Interface in
the Future World of Pollution, Increased Exploitation
of Natural Resources and the Quest of a Bio-Friendly
Society ................................................. 2
1.2 Understanding How and Where the Plants We Know Today
Occur and Interact with the Mineral World: The Setting
that we Live in Today and its History ................... 4
1.2.1 Configuration of the Surface Environment of the
Earth: Mountains and Climate ..................... 5
1.2.2 Vegetation and Climate Today and Yesterday ....... 9
1.2.3 Present Day Context of Plant Biomes ............. 10
1.2.4 Local Variations in the Chemical Context
(Geology) and Climatic Variables of Plant -
Soil Interaction ................................ 13
1.2.5 Summary ......................................... 18
1.3 An Unorthodox but Operational Definition Mineral
Types and Functions for Phyllosilicate Clay Minerals ... 18
1.3.1 Network Structures .............................. 19
1.3.2 Substitutions and Layer Charge .................. 22
1.3.3 Interlayer Ion Occupancy ........................ 23
1.3.4 Identification of Phyllosilicate Clay Types ..... 24
1.3.5 Classification of 2:1 Minerals .................. 27
1.3.6 Identification of Smectites and Illites ......... 28
1.3.7 Mixed Layer Illite/Smectite Crystals ............ 28
1.3.8 Identification of Soil HI Minerals
("Vermiculite") ................................. 31
1.3.9 Potassium Saturation and Identification of 2:1
Clay Types ...................................... 31
1.3.10 Summary ......................................... 34
1.4 Recommendations ........................................ 35
1.5 К Saturation (1 M Solution) ............................ 36
1.5.1 Summary ......................................... 37
References ............................................. 37
2 The Soil Profile: The Structure of Plant - Mineral
Interaction Space ........................................... 41
2.1 Origins of Alteration Clay Mineral Formation ........... 41
2.2 Some Fundamental Principles in the Alteration of
a Rock are as Follows .................................. 43
2.2.1 Thermal expansion ............................... 43
2.2.2 Chemical Controls ............................... 44
2.2.3 Biological Degradation of Rocks and Minerals .... 52
2.2.4 Summary ......................................... 61
2.3 The Alteration - Soil Profile: Transformation of
Rocks into Clay, Sand and Organic Matter Complexes ..... 62
2.3.1 The Transformation of Bedrock into Soil Clays ... 64
2.3.2 Summary ......................................... 70
2.3.3 The Alteration Profile .......................... 72
2.3.4 Summary ......................................... 75
2.3.5 The Plant - Mineral Continuum, the A Horizon .... 75
2.4 Soil Classifications: Descriptions and Factors
Affecting Alteration Profiles .......................... 80
2.4.1 Classification .................................. 81
2.4.2 Results of Soil Forming Processes on the
Structure of an Alteration Profile .............. 83
2.4.3 Summary ......................................... 87
References ............................................. 88
3 Physical Factors Affecting Soil Profiles: The Three
Dimensional Aspect of Plant - Mineral Interaction:
Displacements ............................................... 93
3.1 Movement of Clay and Soil Material ..................... 94
3.1.1 Movement of Clay Particles Within the Soil
Zone: Internal Loss of Material ................. 95
3.1.2 Erosion of Fine Grained Materials From the
Surface and Transportation by Water ............. 99
3.1.3 Surface Erosion by Wind Action and Consequent
Loess Deposition ............................... 101
3.1.4 Summary ........................................ 103
3.1.5 Transportation and Displacement by Mass
Mechanical Failure: Landslides and Slumps ...... 104
3.2 Retention of Soils and Clay Material by Plants ........ 107
3.2.1 Surface Displacement and Plants ................ 107
3.2.2 The Physical Role of Roots in Stabilizing
Alteration Materials ........................... 110
3.3 Fixing and Accumulating Clays in the Surface
Horizons .............................................. 119
3.3.1 Plants as Accumulators of Soil Materials ....... 119
3.3.2 Plants and Clays in Profiles: Stabilization
and Regeneration ............................... 122
References ................................................. 127
4 Clay Minerals in Soils: The Interface Between Plants and
the Mineral World .......................................... 129
4.1 The Silicate Clay Mineral Types Present in Soils ...... 129
4.1.1 Kaolinite and Halloysite, 1:1 Minerals ......... 130
4.1.2 The 2:1 Clay Minerals in Soils ................. 131
4.1.3 Complex Mixed Layer Minerals (KS): Smectite,
Kaolinite and Kaolinite/Smectite Mixed Layer
Minerals ....................................... 146
4.1.4 Oxides and Hydroxides .......................... 146
4.1.5 Poorly Crystallized Silicates Imogolite and
Allophone (Allophone Si - Rich, Imogolite
Si = Al) ....................................... 150
4.1.6 Some Minerals Formed and Found at the Surface
but Not in Soils ............................... 154
4.2 The Critical Clays, the 2:1 Clay Minerals in the
A Horizon: Examples in Soil Profiles Showing the
Effects of Plants and Their Bio-agents ................ 156
4.2.1 Trees of Different Types: Conifer and
Deciduous ...................................... 156
4.2.2 Trees and Prairies: Contrasts Brought About
by Plant Regime ................................ 156
4.2.3 Climate, Plants and Soil Clays ................. 165
References ............................................ 167
5 The Chemistry and Mineralogy of Plant and Soil
Interactions: Plant as Manipulators of Their Environment ... 171
5.1 Soil Properties Pertinent to the Prosperity of
Plants ................................................ 171
5.1.1 Terrestrial Plants and Peri-Maritime Plants:
Alkali Content ................................. 171
5.1.2 Elements Needed by Plants ...................... 173
5.1.3 Clay Minerals .................................. 175
5.1.4 Cation Exchange in Soils ....................... 183
5.1.5 Role of Clay Minerals in Critical Nutrient
Exchange: Potassium and Ammonium ............... 187
5.2 Organic Matter, Clay Minerals and Soil Aggregation
(Water Resources for Plants) .......................... 191
5.2.1 Clay Minerals and Organic Molecules
Interactions: Soil Structure Development ....... 191
5.2.2 Consequences of Clay - Organic Interactions:
Soil Structure and Aggregation ................. 195
5.3 Plants and Soil Chemistry ............................. 205
5.3.1 Plant Compositions and Chemical Needs .......... 205
5.3.2 Chemical Profiles in Soils and Alterites
Engendered by Plant Activity and Resulting
Clay Mineralogy ................................ 211
5.4 Impact of Plants on Clay Minerals and Soil Formation
According to Biome Type ............................... 219
5.4.1 Prairie and Forest Type Profiles ............... 220
5.4.2 Comparing Forest and Prairie Soils ............. 223
5.4.3 Successions and Soil Properties Influenced by
Change in Plant Regime ......................... 228
5.5 Mineral Element Transfer in Soils: The Translocation
Effect ................................................ 231
5.5.1 Chemical Variability as a Function of
Alteration Profiles ............................ 231
5.5.2 Parameters of the Translocation Effect ......... 240
5.5.3 Modelling Mineral Stability .................... 245
References ............................................ 249
6 Man and Agriculture: Manipulating Soil - Plant
Interactions ............................................... 255
6.1 The Adventure of Agriculture: the Manipulation of
Nature by Man ......................................... 255
6.1.1 Introduction ................................... 256
6.1.2 History of Traditional Agriculture in Europe:
An Example of Soil - Plant Manipulation:
Changing the Landscape Through Agriculture ..... 259
6.1.3 Summary of Classical Farming Practice .......... 272
6.1.4 Science and Agriculture ........................ 273
6.1.5 The American Experience: A Counter Example of
Soil Use in the Classical Period ............... 279
6.1.6 Change in Agricultural Land Use ................ 281
6.2 Effects of Modern Agriculture on Soil Properties:
Organic and Clay Mineral Changes ...................... 284
6.2.1 Organic Matter and Clay Content ................ 285
6.2.2 Clay Content of Soils .......................... 285
6.2.3 Tillage Practice ............................... 288
6.2.4 Agricultural Practice and Its Results .......... 288
6.2.5 Summary ........................................ 301
References ............................................ 301
7 Plants and Soils: The Ecological Paradigm of Plants and
Clays ...................................................... 305
7.1 Stabilizing 2:1 Clays ................................. 307
7.2 Potassium Retention ................................... 308
7.3 Humic Matter, Soil Aggregates and Water Potential ..... 310
7.4 Modelling Chemical Stability .......................... 311
7.5 Roots and Landscapes .................................. 312
7.6 New Pathways .......................................... 313
Reference ............................................. 313
Annex A
Simplified Methods for the Interpretation of X-Ray
Diffraction Diagrams of Soil Clay Assemblages .............. 315
Annex I X-ray Diffraction Diagrams of Soil Clay
Assemblages and a Simplified Method of their
Interpretation .......................................... 315
Decomposition Methods ................................... 315
Some Fundamental Concepts of Decomposition Techniques ... 317
Annex II Identification of the Major Groups of Clay
Minerals ................................................ 329
Major Mineral Types ..................................... 329
Inter-Layering of Structural Types ...................... 330
References ................................................. 336
Index ......................................................... 337
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