Soil Clays : Linking Geology, Biology, Agriculture, and the Environment

Introduction and definitions -- Soil clays : mineralogy -- Geology : defining the starting point for soil and clay formation -- Primary minerals and their alteration by weathering -- Driving forces of alteration -- Chemistry of alteration by weathering -- Formation of clays in the soil zone of alteration -- Nature and origin of surface soil clays -- The importance of climate in the formation of soil clays -- Associations of soil clays -- Occurrence and extraction of soil clays -- Identification and quantification of clay minerals in soils -- Surfaces, surface reactions, and particle size effects -- Role of soil clays in agriculture, the environment, and society -- Summary.;"This book aims to help improve predictions of important properties of soils through a modern understanding of their highly reactive clay minerals as they are formed and occur in soils worldwide. It examines how clays occur in soils and the role of soil clays in disparate applications"-- Cover......Page 1 Half Title......Page 2 Title Page......Page 4 Copyright Page......Page 5 Dedication......Page 6 Table of Contents......Page 8 Preface......Page 14 References......Page 16 Authors......Page 18 1.1 Soil......Page 20 1.2 The Origin of Soils and Clays in Geological Time......Page 21 1.3 Weathering as the Origin of (Most) Soils......Page 22 1.4 From Rock to Soil: The Biological Factor in the Initial Stages of Rock Alteration and Soil Formation......Page 23 1.5 Soil Science......Page 26 1.6 Clays......Page 27 1.7 Clay Mineral Formation......Page 28 1.8 Soil Clay Mineralogy......Page 31 1.9 A new approach to the study of soil clays......Page 32 References......Page 33 2.1 Basic Structures of Phyllosilicates......Page 36 2.2 Lattice Substitutions......Page 38 2.4 Residual Charge on 2:1 Structure due to Ionic Substitutions and Site Occupation......Page 40 2.4.1 Names for 2:1 Structure Minerals in Soils......Page 41 2.6 Cation Exchange in Interlayer Sites......Page 43 2.7 Cation Exchange Sites on Clay Edges......Page 45 2.8.1 Cation–Water Interaction......Page 47 2.8.1.1 Cation–Water Interaction: Summary......Page 48 2.8.1.5 Cation Exchange on Edge Sites: Summary......Page 49 2.8.2 Overall Effect of pH on Exchange (Capture or Loss) of Cations......Page 50 2.10 Mixed-Layered Clays......Page 51 2.11 Identification of Layer Silicate Clays (2:1 and 1:1 Structures) by X-Ray Diffraction......Page 52 2.12 Allophane and Imogolite......Page 53 2.13 Iron Oxides, Hydroxides and Oxyhydroxides......Page 54 2.15 Manganese Oxides......Page 55 References......Page 56 3.2 Geology of the Continental Surfaces......Page 60 3.3.1 Silicates......Page 61 3.3.2 Non-Silicates......Page 63 3.3.3 The Initial Production of Clays in Weathering......Page 64 3.3.4.2 Sediments......Page 66 3.3.4.3 Loess and Dust......Page 67 References......Page 70 4.1.3 Volcanic Glass......Page 72 4.1.6 Chlorites......Page 73 4.2.1 Oxidation......Page 74 4.2.3 Effects of pH......Page 75 References......Page 76 5.2 Topography......Page 78 5.2.1 Interaction at the Water–Rock Interface......Page 79 5.3.1 Alteration Profile......Page 82 5.3.2 Rock Alteration by Pore Water......Page 83 5.3.4 Geology and Alteration......Page 84 References......Page 87 6.2 Chemical Forces......Page 88 6.3 Chemistry of Elements and Mineral Stability......Page 89 6.4.1 Mineral Change: Loss of Mineralogical Identity......Page 90 6.4.3 Interaction by Diffusion and Ion Exchange......Page 91 6.4.4 Oxidation......Page 93 6.5.2 Mineral Growth from Amorphous Materials......Page 94 6.5.3 Mineral Transformation......Page 95 References......Page 96 7.1 Crystallisation from Incongruent Dissolution......Page 98 7.2.1 Neogenesis......Page 99 7.2.1.1 Thermodynamic Explanation of Stability of Minerals......Page 100 7.2.2 Transformation of Minerals......Page 101 7.3 Effect of Plants on Soil Clay Assemblages......Page 104 7.3.2 Transformation of Pre-Existing Phyllosilicate Minerals of High Temperature Origin......Page 105 7.3.3 Formation of Mixed-Layered 2:1 Clays......Page 106 7.3.4 Formation of Palygorskite and Sepiolite in Soils......Page 107 7.3.5.1 Interstratifications of Kaolinite and Smectite and Their Evolution......Page 108 7.3.6 Crystallisation of 1:1 Clays in Soils......Page 109 7.3.7 Formation of Oxyhydroxide Al- and Fe-Dominated Soil Clay Assemblages......Page 111 7.3.8 Formation of Other Oxides......Page 112 7.3.10 Biology and Its Effect on Clays and Clay Associations in Soils......Page 113 References......Page 114 8.2 Vermiculites (2:1)......Page 122 8.4 Mixed-Layered 2:1 Minerals......Page 127 8.5 Kaolin-Smectites Interstratified (1:1–2:1)......Page 132 8.7 Halloysite (1:1)......Page 135 8.8 Allophane (1:2 to 1:1) and Imogolite (1:2)......Page 140 8.9 Palygorskite and Sepiolite (2:1 Si:Mg)......Page 142 8.10 Oxides and Rarer Minerals......Page 144 References......Page 145 Chapter 9: The Importance of Climate in the Formation of Soil Clays......Page 160 9.1 Cold and Cool Zones......Page 161 9.2 Warm Zone......Page 162 9.3 Hot Zone......Page 163 9.4 Mechanisms of Change......Page 165 References......Page 166 10.1 Organic Matter......Page 170 10.2 Charges on Clay Particles......Page 171 10.3 Organo-Mineral Interactions......Page 173 10.4 Combined Indications on Links between Minerals and SOM......Page 179 10.5 Formation and Stabilisation of Microaggregates......Page 180 10.6.1 Organic Particle Size and Fixation on Different Clay-Sized Particles (OM Content and Clay-Size Fraction)......Page 183 10.6.2 Formation of Macroaggregates......Page 184 10.6.4 Macroaggregates and Soil Structure: The Formation of Fractures......Page 185 10.6.6 Organic Matter and Clay Structures and Retention of Capillary Water......Page 186 References......Page 187 11.1 Clay Associations......Page 194 11.2 Extraction of Soil Clays......Page 197 11.3 Recommended Procedures......Page 201 References......Page 202 12.2 Identification and Analyses of Soil Clays by Chemical Extractions......Page 204 12.5 Identification of Soil Clays by Electron Microscopy......Page 206 12.7 Quantitative Analyses......Page 207 References......Page 208 13.1 Soil Clays and Surface Areas......Page 212 13.2.1 Effect of Organic Matter on Surface Areas......Page 213 13.4 Effect of Associations upon Charges on Soils and Soil Clays......Page 214 13.5 Effects of Particle Size......Page 217 13.6 Integration: Importance of Phenomena; Limitations of Measurements......Page 218 References......Page 219 14.1 Plant Nutrition......Page 222 14.2 Soil Structure and Water Holding and Supply......Page 223 14.3 Formation and Stabilisation of Pores......Page 225 14.4 Aggregation, Pores and Soil Quality......Page 227 14.5 Bulk Soil Physical Properties......Page 228 14.6 Carbon Sequestration......Page 235 14.7 Pollution and Its Remediation......Page 237 14.8 Medicine......Page 239 14.9 Forensics......Page 240 14.10 Archaeology and Environmental History......Page 241 References......Page 242 15.2 Clays (from Chapter 2)......Page 248 15.3 Formation of Clays in Soils (from Chapters 3–7)......Page 249 15.4 Types of Clays and Their Origins (from Chapters 8 and 9)......Page 251 15.5 Associations of Clays in Soils (from Chapter 10)......Page 253 15.6 Extraction of Clays from Soil, and Their Identification and Quantification (from Chapters 11 and 12)......Page 255 15.8 Role of Soil Clays in Applications in Agriculture, the Environment and Society (from Chapter 14)......Page 256 15.9 Résumé......Page 258 Bibliography......Page 259 A.2 Decomposition Methods......Page 260 A.3.2 Principles for Decomposition......Page 261 A.3.3 Decomposition Examples......Page 264 A.3.4 Peak Shape and Intensity Change: The Comparative Method......Page 266 A.3.5 Surface Area......Page 267 A.4 Centre of Gravity......Page 268 3.5.2 Peaks......Page 269 References......Page 270 Index......Page 272 As the human population grows from seven billion toward an inevitable nine or 10 billion, the demands on the limited supply of soils will grow and intensify. Soils are essential for the sustenance of almost all plants and animals, including humans, but soils are virtually infinitely variable. Clays are the most reactive and interactive inorganic compounds in soils. Clays in soils often differ from pure clay minerals of geological origin. They provide a template for most of the reactive organic matter in soils. They directly affect plant nutrients, soil temperature and pH, aggregate sizes and strength, porosity and water-holding capacities. This book aims to help improve predictions of important properties of soils through a modern understanding of their highly reactive clay minerals as they are formed and occur in soils worldwide. It examines how clays occur in soils and the role of soil clays in disparate applications including plant nutrition, soil structure, and water-holding capacity, soil quality, soil shrinkage and swelling, carbon sequestration, pollution control and remediation, medicine, forensic investigation, and deciphering human and environmental histories. Features: Provides information on the conditions that lead to the formation of clay minerals in soils Distinguishes soil clays and types of clay minerals Describes clay mineral structures and their origins Describes occurrences and associations of clays in soil Details roles of clays in applications of soils Heavily illustrated with photos, diagrams, and electron micrographs Includes user-friendly description of a new method of identification To know soil clays is to enable their use toward achieving improvements in the management of soils for enhancing their performance in one or more of their three main functions of enabling plant growth, regulating water flow to plants, and buffering environmental changes. This book provides an easily-read and extensively-illustrated description of the nature, formation, identification, occurrence and associations, measurement, reactivities, and applications of clays in soils.