ENCYCLOPEDIA OF SOILS IN THE ENVIRONMENT ppt

Rounding out the encyclopedia's excellent coverage,contributions cover cross-disciplinary subjects, such as the history of soil utilizationfor agricultural and engineering purposes and s

FOUR-VOLUME SET

by Daniel Hillel (Editor-in-Chief)

Hardcover: 2200 pagesPublisher: Academic Press; 1 edition (November 8, 2004)Language: English

ISBN-10: 0123485304ISBN-13: 978-0123485304

Book Description

More than ever before, a compelling need exists for an encyclopedic resource about soilthe rich mix of mineral particles, organic matter, gases, and soluble compounds that foster both plant and animal growth Civilization depends more on the soil as human populations continue to grow and increasing demands are placed upon available resources

The Encyclopedia of Soils in the Environmentis a comprehensive and integrated consideration of a topic of vital importance to human societies in the past, present, and future.This important work encompasses the present knowledge of the world's variegated soils,their origins, properties, classification, and roles in the biosphere A team of outstanding,international contributors has written over 250 entries that cover a broad range of issuesfacing today's soil scientists, ecologists, and environmental scientists

This four-volume set features thorough articles that survey specific aspects of soil biology,ecology, chemistry and physics Rounding out the encyclopedia's excellent coverage,contributions cover cross-disciplinary subjects, such as the history of soil utilizationfor agricultural and engineering purposes and soils in relation to the remediation of pollutionand the mitigation of global climate change

This comprehensive, yet accessible source is a valuable addition to the library of scientists,researchers, students, and policy makers involved in soil science, ecology, and environmentalscience

Also available online via ScienceDirect featuring extensive browsing, searching, and internal cross-referencing between articles in the work, plus dynamic linking to journalarticles and abstract databases, making navigation flexible and easy For more information,pricing options and availability visit www.info.sciencedirect.com

* A distinguished international group of editors and contributors

* Well-organized encyclopedic format providing concise, readable entries, easy searches, and thorough cross-references

* Abundant visual resources — photographs, figures, tables, and graphs — in every entry

* Complete up-to-date coverage of many important topics — essential information for scientists, students and professionals alike

EDITOR-IN-CHIEFDaniel HillelColumbia UniversityNew York, NYUSA

EDITORIAL ADVISORY BOARD

Brazil

K RitzCranfield UniversitySilsoe

UK

R SchulinSwiss Federal Institute of Technology ZurichSchlieren

Switzerland

N SenesiUniversita` di BariBari

Italy

J T SimsUniversity of DelawareNewark, DE

USA

K SmithUniversity of EdinburghEdinburgh

UK

R L TateRutgers UniversityNew Brunswick, NJUSA

N van BreemenWageningen Agricultural UniversityWageningen

The Netherlands

W H van RiemsdijkDepartment of Soil QualityWageningen

The Netherlands

The Encyclopedia of Soils in the Environment is a vitally important scientific publication and an equallyimportant contribution to global public policy The Encyclopedia brings together a remarkable range ofcutting-edge scientific knowledge on all aspects of soil science, as well as the links of soils and soil science toenvironmental management, food production, biodiversity, climate change, and many other areas of signi-ficant concern Even more than that, the Encyclopedia will immediately become an indispensable resource forpolicy makers, analysts, and students who are focusing on one of the greatest challenges of the 21st century.With 6.3 billion people, our planet is already straining to feed the world’s population, and is failing to do soreliably in many parts of the world The numbers of chronically poor in the world have been stuck at some 800million in recent years, despite long-standing international goals and commitments to reduce that number byseveral hundred million Yet the challenge of food production will intensify in coming decades, as the humanpopulation is projected to rise to around 9 billion by mid-century, with the increased population concentrated

in parts of the world already suffering from widespread chronic under-nourishment

Unless the best science is brought to these problems, the situation is likely to deteriorate sharply Food productionsystems are already under stress, for reasons often related directly to soils management In Africa, crop yields aredisastrously low and falling in many places due to the rampant depletion of soil nutrients This situation needsurgent reversal, through increasing use of agro-forestry techniques (e.g inter-cropping cereals with leguminousnitrogen-fixing trees) and increasing the efficient applications of chemical fertilizers In other impoverished, as well

as rich, parts of the planet, decades of intensive agriculture under irrigation have led to salinization, water-logging,eutrophication of major water bodies, dangerous declines of biodiversity and other forms of environmentaldegradation These enormous strains are coupled with the continuing pressures of tropical deforestation and thelack of new promising regions for expanding crop cultivation to meet the needs of growing populations Finally,there looms the prospect of anthropogenic climate change Global warming and associated complex and poorlyunderstood shifts in precipitation extremes and other climate variables all threaten the world’s natural ecosystemsand food production systems in profound yet still imperfectly understood ways The risks of gradual or abruptclimate change are coupled with the risks of drastic perturbations to regional and global food supplies

The Encyclopedia offers state-of-the-art contributions on each of these challenges, as well as links to entries

on the fundamental biophysical processes that underpin the relevant phenomena The scale and class collaboration that stands behind this unique project signifies its importance for the world community

world-It is an honor and privilege for me to introduce this path-breaking endeavor

Jeffrey D SachsDirectorThe Earth Institute at Columbia UniversityQuetelet Professor of Sustainable Development

Columbia University, New York, USA

The term ‘soil’ refers to the weathered and fragmented outer layer of our planet’s land surfaces Formedinitially through the physical disintegration and chemical alteration of rocks and minerals by physical andbiogeochemical processes, soil is influenced by the activity and accumulated residues of a myriad of diverseforms of life As it occurs in different geologic and climatic domains, soil is an exceedingly variegated bodywith a wide range of attributes

Considering the height of the atmosphere, the thickness of the earth’s rock mantle, and the depth of theocean, one observes that soil is an amazingly thin body – typically not much more than one meter thick andoften less than that Yet it is the crucible of terrestrial life, within which biological productivity is generatedand sustained It acts like a composite living entity, a home to a community of innumerable microscopic andmacroscopic plants and animals A mere fistful of soil typically contains billions of microorganisms, whichperform vital interactive biochemical functions Another intrinsic attribute of the soil is its sponge-likeporosity and its enormous internal surface area That same fistful of soil may actually consist of severalhectares of active surface, upon which physicochemical processes take place continuously

Realizing humanity’s utter dependence on the soil, ancient peoples, who lived in greater intimacy withnature than many of us today, actually revered the soil It was not only their source of livelihood, but also thematerial from which they built their homes and that they learned to shape, heat, and fuse into householdvessels and writing tablets (ceramic, made of clayey soil, being the first synthetic material in the history oftechnology) In the Bible, the name assigned to the first human was Adam, derived from ‘adama,’ meaning soil.The name given to that first earthling’s mate was Hava (Eve, in transliteration), meaning ‘living’ or ‘life-giving.’Together, therefore, Adam and Eve signified quite literally ‘Soil and Life.’

The same powerful metaphor is echoed in the Latin name for the human species – Homo, derived fromhumus, the material of the soil Hence, the adjective ‘human’ also implies ‘of the soil.’ Other ancient culturesevoked equally powerful associations To the Greeks, the earth was a manifestation of Gaea, the maternalgoddess who, impregnated by Uranus (god of the sky), gave birth to all the gods of the Greek pantheon.Our civilization depends on the soil more crucially than ever, because our numbers have grown whileavailable soil resources have diminished and deteriorated Paradoxically, however, even as our dependence onthe soil has increased, most of us have become physically and emotionally detached from it Many of thepeople in the so-called ‘developed’ countries spend their lives in the artificial environment of a city, insulatedfrom direct exposure to nature, and some children may now assume as a matter of course that food originates

in supermarkets

Detachment has bred ignorance, and out of ignorance has come the delusion that our civilization has risenabove nature and has set itself free of its constraints Agriculture and food security, erosion and salination,degradation of natural ecosystems, depletion and pollution of surface waters and aquifers, and decimation ofbiodiversity – all of these processes, which involve the soil directly or indirectly – have become abstractions tomany people The very language we use betrays disdain for that common material underfoot, often referred to

as ‘dirt.’ Some fastidious parents prohibit their children from playing in the mud and hurry to wash their

‘soiled’ hands when the children nonetheless obey an innate instinct to do so Thus soil is devalued and treated

as unclean though it is the terrestrial realm’s principal medium of purification, wherein wastes are decomposedand nature’s productivity is continually rejuvenated.

Scientists who observe soil closely see it in effect as a seething foundry in which matter and energy are inconstant flux Radiant energy from the sun streams onto the field and cascades through the soil and the plantsgrowing in it Heat is exchanged, water percolates through the soil’s intricate passages, plant roots extractwater and transmit it to their leaves, which transpire it back to the atmosphere Leaves absorb carbon dioxidefrom the air and synthesize it with soil-derived water to form the primary compounds of life Oxygen emitted

by the leaves makes the air breathable for animals, which consume and in turn fertilize plants

Soil is thus a self-regulating bio-physio-chemical factory, processing its own materials, water, and solarenergy It also determines the fate of rainfall and snowfall reaching the ground surface – whether the water thusreceived will flow over the land as runoff, or seep downward to the subterranean reservoir called groundwater,which in turn maintains the steady flow of springs and streams With its finite capacity to absorb and storemoisture, and to release it gradually, the soil regulates all of these phenomena Without the soil as a buffer, rainfalling over the continents would run off entirely, producing violent floods rather than sustained river flow.Soil naturally acts as a living filter, in which pathogens and toxins that might otherwise accumulate to foulthe terrestrial environment are rendered harmless Since time immemorial, humans and other animals havebeen dying of all manner of disease and have then been buried in the soil, yet no major disease is transmitted by

it The term antibiotic was coined by soil microbiologists who, as a consequence of their studies of soil bacteriaand actinomycetes, discovered streptomycin (an important cure for tuberculosis and other infections) Ionexchange, a useful process of water purification, also was discovered by soil scientists studying the passage ofsolutes through beds of clay

However unique in form and function, soil is not an isolated body It is, rather, a central link in the largerchain of interconnected domains and processes comprising the terrestrial environment The soil interacts bothwith the overlying atmosphere and the underlying strata, as well as with surface and underground bodies ofwater Especially important is the interrelation between the soil and the climate In addition to its function ofregulating the cycle of water, it also regulates energy exchange and surface temperature

When virgin land is cleared of vegetation and turned into a cultivated field, the native biomass above theground is often burned and the organic matter within the soil tends to decompose These processes releasecarbon dioxide into the atmosphere, thus contributing to the earth’s greenhouse effect and to global warming

On the other hand, the opposite act of reforestation and soil enrichment with organic matter, such as can beachieved by means of conservation management, may serve to absorb carbon dioxide from the atmosphere To

an extent, the soil’s capacity to store carbon can thus help to mitigate the greenhouse effect

Thousands of years are required for nature to create life-giving soil out of sterile bedrock In only a fewdecades, however, unknowing or uncaring humans can destroy that wondrous work of nature In variouscircumstances, mismanaged soils may be subject to erosion (the sediments of which tend to clog streambeds,estuaries, lakes, and coastal waters), to leaching of nutrients with attendant loss of fertility and eutrophication

of water bodies, to waterlogging and impaired aeration, or to an excessive accumulation of salts that maycause a once-productive soil to become entirely sterile Such processes of soil degradation, sometimes called

‘desertification,’ already affect large areas of land

We cannot manage effectively and sustainably that which we do not know and thoroughly understand That

is why the tasks of developing and disseminating sound knowledge of the soil and its complex processes haveassumed growing urgency and importance The global environmental crisis has created a compelling need for aconcentrated, concise, and definitive source of information – accessible to students, scientists, practitioners,and the general public – about the soil in all its manifestations – in nature and in relation to the life of humans

Daniel HillelEditor-in-ChiefMay 2004

The Encyclopedia of Soils in the Environment contains nearly 300 articles, written by the world’s leadingauthorities Pedologists, biologists, ecologists, earth scientists, hydrologists, climatologists, geographers, andrepresentatives from many other disciplines have contributed to this work Each of the articles separately, andall of them in sequence and combination, serve to summarize and encapsulate our present knowledge of theworld’s variegated soils, their natural functions, and their importance to humans

Concise articles surveying specific aspects of soils (soil genesis, soil chemistry and mineralogy, soil physicsand hydrology, and soil biology) are complemented by articles covering transdisciplinary aspects, such as therole of soils in ecology, the history of soil utilization for agricultural and engineering purposes, the develop-ment of soil science as a discipline, and the potential or actual contributions of soils to the generation, as well

as to the mitigation, of pollution and of global climate change

This comprehensive reference encompasses both the fundamental and the applied aspects of soil science,interfacing in general with the physical sciences and life sciences and more specifically with the earth sciencesand environmental sciences

The Encyclopedia of Soils in the Environment manifests the expanding scope of modern soil science, fromits early sectarian focus on the utilitarian attributes of soils in agriculture and engineering, to a wider and muchmore inclusive view of the soil as a central link in the continuous chain of processes constituting the dynamicenvironment as a whole Thus it both details and integrates a set of topics that have always been of vitalimportance to human societies and that are certain to be even more so in the future

Daniel HillelEditor-in-ChiefMay 2004

Contents are given as follows: CHAPTER NAME Author(s) Page number

VOLUME 1

A

ACID RAIN AND SOIL ACIDIFICATION L Blake 1

ACIDITY N Bolan, D Curtin and D Adriano 11

AERATION D E Rolston 17

AGGREGATION

Microbial Aspects S D Frey 22

Physical Aspects J R Nimmo 28

AGROFORESTRY P K R Nair 35

AIR PHASE see AERATION; DIFFUSION

ALBEDO see ENERGY BALANCE; RADIATION BALANCE

ALLOPHANE AND IMOGOLITE see AMORPHOUS MATERIALS

ALLUVIUM AND ALLUVIAL SOILS J L Boettinger 45

ALUMINUM SPECIATION D R Parker 50

AMMONIA D E Kissel and M L Cabrera 56

AMORPHOUS MATERIALS J Harsh 64

ANAEROBIC SOILS P W Inglett, K R Reddy and R Corstanje 72

ANION EXCHANGE see CATION EXCHANGE

APPLICATIONS OF SOILS DATA P J Lawrence 78

BIOCONTROL OF SOIL-BORNE PLANT DISEASES C E Pankhurst and J M Lynch 129

BIODIVERSITY D H Wall 136

BUFFERING CAPACITY B R James 142

BULK DENSITY see POROSITY AND PORE-SIZE DISTRIBUTION

C

CALCIUM AND MAGNESIUM IN SOILS N Bolan, P Loganathan and S Saggar 149CAPILLARITY D Or and M Tuller 155

CARBON CYCLE IN SOILS

Dynamics and Management C W Rice 164

Formation and Decomposition C A Cambardella 170

CARBON EMISSIONS AND SEQUESTRATION K Paustian 175

CATION EXCHANGE L M McDonald, V P Evangelou and M A Chappell 180

CHEMICAL EQUILIBRIA A P Schwab 189

CHEMICAL SPECIATION MODELS see SURFACE COMPLEXATION MODELINGCHERNOZEMS see GRASSLAND SOILS

CHILDS, ERNEST CARR E G Youngs 195

CIVILIZATION, ROLE OF SOILS D Hillel 199

CLASSIFICATION OF LAND USE see LAND-USE CLASSIFICATION

CLASSIFICATION OF SOILS R W Arnold 204

CLASSIFICATION SYSTEMS

Australian R W Fitzpatrick 211

FAO F O Nachtergaele 216

Russian, Background and Principles M Gerasimova 223

Russian, Evolution and Examples D Konyushkov 227

USA D J Brown 235

CLAY MINERALS D G Schulze 246

CLIMATE CHANGE IMPACTS P Bullock 254

CLIMATE MODELS, ROLE OF SOIL P Smith 262

COLLOID-FACILITATED SORPTION AND TRANSPORT R Kretzschmar 276

COMPACTION J J H van den Akker and B Soane 285

COMPOST T L Richard 294

CONDITIONERS R E Sojka, J A Entry and W J Orts 301

CONSERVATION see EROSION: Water-Induced; Wind-Induced; SUSTAINABLE SOIL AND LAND

MANAGEMENT; TERRACES AND TERRACINGCONSERVATION TILLAGE M R Carter 306

COVER CROPS L Edwards and J Burney 311

CROP ROTATIONS C A Francis 318

CROP WATER REQUIREMENTS L S Pereira and I Alves 322

CROP-RESIDUE MANAGEMENT D C Reicosky and A R Wilts 334

CRUSTS

Biological J Belnap 339

Structural R L Baumhardt and R C Schwartz 347

CULTIVATION AND TILLAGE M R Carter and E McKyes 356

D

DARCY’S LAW D Swartzendruber 363

DEGRADATION C J Ritsema, G W J van Lynden, V G Jetten and S M de Jong 370

DENITRIFICATION D A Martens 378

DESERTIFICATION D Hillel and C Rosenzweig 382

DIFFUSION T Addiscott and P Leeds-Harrison 389

DISINFESTATION A Gamliel and J Katan 394

DISPERSION see FLOCCULATION AND DISPERSION

DISSOLUTION PROCESSES, KINETICS K G Scheckel and C A Impellitteri 400

DRAINAGE, SURFACE AND SUBSURFACE N R Fausey 409

DRYLAND FARMING G A Peterson 414

ELECTROSTATIC DOUBLE-LAYER see CATION EXCHANGE

ENERGY BALANCE M Fuchs 438

ENVIRONMENTAL MONITORING P J Loveland and P H Bellamy 441

ENZYMES IN SOILS R P Dick and E Kandeler 448

EROSION

Irrigation-Induced G A Lehrsch, D L Bjorneberg and R E Sojka 456

Water-Induced J E Gilley 463

Wind-Induced T M Zobeck and R S Van Pelt 470

ESSENTIAL ELEMENTS E A Kirkby 478

EUTROPHICATION A J Gold and J T Sims 486

EVAPORATION OF WATER FROM BARE SOIL C W Boast and F W Simmons 494

EVAPOTRANSPIRATION G Stanhill 502

F

FACTORS OF SOIL FORMATION

Biota A H Jahren 507

Climate O C Spaargaren and J A Deckers 512

Human Impacts J Sandor, C L Burras and M Thompson 520

Parent Material K R Olson 532

Time E F Kelly and C M Yonker 536

FAUNA T Winsome 539

FERTIGATION U Kafkafi and S Kant 1

FERTILITY J L Havlin 10

FERTILIZERS AND FERTILIZATION H W Scherer 20

FIELD CAPACITY see WATER CYCLE

FLOCCULATION AND DISPERSION I Shainberg and G J Levy 27

FLUORESCENCE SPECTROSCOPY N Senesi and V D’Orazio 35

FOLIAR APPLICATIONS OF NUTRIENTS M Tagliavini and M Toselli 53

FOOD-WEB INTERACTIONS P C de Ruiter and J C Moore 59

FORENSIC APPLICATIONS W F Rowe 67

FOREST SOILS J R Boyle 73

FOURIER TRANSFORM INFRARED SPECTROSCOPY D Peak 80

FRACTAL ANALYSIS Y Pachepsky and J W Crawford 85

FREEZING AND THAWING

Cycles B Sharratt 98

Processes G N Flerchinger, G A Lehrsch and D K McCool 104

FUNGI K Ritz 110

G

GEOGRAPHICAL INFORMATION SYSTEMS J Bo¨hner, T Selige and R Ko¨the 121

GERMINATION AND SEEDLING ESTABLISHMENT A Hadas 130

GLOBAL WARMING see CARBON EMISSIONS AND SEQUESTRATION; CLIMATE CHANGE IMPACTS;

GREENHOUSE GAS EMISSIONS

GRASSLAND SOILS J A Mason and C W Zanner 138

GREEN MANURING see COVER CROPS

GREENHOUSE GAS EMISSIONS K A Smith 145

GROUNDWATER AND AQUIFERS Y Bachmat 153

GROUNDWATER POLLUTION see POLLUTION: Groundwater

HEAT AND MOISTURE TRANSPORT R Horton and A Globus 169

HEAT CAPACITY see THERMAL PROPERTIES AND PROCESSES

HEAT FLOW see THERMAL PROPERTIES AND PROCESSES

HEAVY METALS D C Adriano, N S Bolan, J Vangronsveld and W W Wenzel 175

HILGARD, EUGENE WOLDEMAR R Amundson 182

HOOGHOUDT, SYMEN BAREND P A C Raats and R R van der Ploeg 188

HUMIFICATION T C Balser 195

HYDRAULIC PROPERTIES, TEMPERATURE EFFECTS S A Grant 207

HYDRIC SOILS G W Hurt 212

HYDROCARBONS P Kostecki, R Morrison and J Dragun 217

HYDRODYNAMIC DISPERSION see SOLUTE TRANSPORT

HYDRODYNAMICS IN SOILS T P A Ferre´ and A W Warrick 227

HYSTERESIS J H Dane and R J Lenhard 231

I

IMMISCIBLE FLUIDS R J Lenhard, J H Dane and M Oostrom 239

INCEPTISOLS A Palmer 248

INDUSTRIAL POLLUTION see POLLUTION: Industrial

INFILTRATION T P A Ferre´ and A W Warrick 254

INFRARED SPECTROSCOPY see FOURIER TRANSFORM INFRARED SPECTROSCOPYIRON NUTRITION K Mengel and H Kosegarten 260

IRRIGATION

Environmental Effects S Topcu and C Kirda 267

Methods D L Bjorneberg and R E Sojka 273

ISOTOPES IN SOIL AND PLANT INVESTIGATIONS K Reichardt and O O S Bacchi 280

ISOTROPY AND ANISOTROPY T-C J Yeh, P Wierenga, R Khaleel and R J Glass 285

J

JENNY, HANS R Amundson 293

KELLOGG, CHARLES J D Helms 301

KINETIC MODELS P M Jardine 307

KIRKHAM, DON D R Nielsen and R R van der Ploeg 315

L

LAMINAR AND TURBULENT FLOW see HYDRODYNAMICS IN SOILS

LANDFILLS see WASTE DISPOSAL ON LAND: Municipal

LAND-USE CLASSIFICATION J A LaGro Jr 321

LAWES, JOHN BENNET AND GILBERT, JOSEPH HENRY A E Johnston 328

LEACHING PROCESSES B E Clothier and S Green 336

LIEBIG, JUSTUS VON R R van der Ploeg, W Bo¨hm and M B Kirkham 343

LIMING E J Kamprath and T J Smyth 350

LIPMAN, JACOB G J C F Tedrow 358

LOESS A J Busacca and M R Sweeney 364

LOWDERMILK, WALTER CLAY J D Helms 373

LYSIMETRY T A Howell 379

M

MACRONUTRIENTS C W Wood, J F Adams and B H Wood 387

MACROPORES AND MACROPORE FLOW, KINEMATIC WAVE APPROACH P F Germann 393MAGNESIUM IN SOILS see CALCIUM AND MAGNESIUM IN SOILS

MANURE MANAGEMENT J T Sims and R O Maguire 402

MARBUT, CURTIS FLETCHER J P Tandarich 410

MATRIC POTENTIAL see HYDRODYNAMICS IN SOILS; WATER POTENTIAL; WATER RETENTION

AND CHARACTERISTIC CURVE

MEDITERRANEAN SOILS J Torrent 418

METAL OXIDES A C Scheinost 428

METALS AND METALLOIDS, TRANSFORMATION BY MICROORGANISMS S M Glasauer,

T J Beveridge, E P Burford, F A Harper and G M Gadd 438

METALS, HEAVY see HEAVY METALS

MICROBIAL PROCESSES

Environmental Factors P G Hartel 448

CommunityAnaly sis C H Nakatsu 455

Kinetics N S Panikov 463

MICRONUTRIENTS L M Shuman 479

MINERAL–ORGANIC–MICROBIAL INTERACTIONS P M Huang, M C Wang and M K Wang 486MINERALS, PRIMARY P M Huang and M K Wang 500

MINERALS, SECONDARY see CLAY MINERALS

MINIMUM TILLAGE see CONSERVATION TILLAGE

MISCIBLE DISPLACEMENT see SOLUTE TRANSPORT

MORPHOLOGY P R Owens and E M Rutledge 511

MULCHES C L Acharya, K M Hati and K K Bandyopadhyay 521

MYCORRHIZAL FUNGI L M Egerton-Warburton, J I Querejeta, M F Allen and S L Finkelman 533

NEMATODES D A Neher and T O Powers 1

NEUTRON SCATTERING M J Fayer and G W Gee 6

NITROGEN IN SOILS

Cycle M S Coyne and W W Frye 13

Nitrates D S Powlson and T M Addiscott 21

Nitrification J I Prosser 31

Plant Uptake A Hodge 39

Symbiotic Fixation J I Sprent 46

NITROGEN FERTILIZERS see FERTILIZERS AND FERTILIZATION

NUCLEAR WASTE DISPOSAL G W Gee, P D Meyer and A L Ward 56

NUTRIENT AVAILABILITY N K Fageria and V C Baligar 63

NUTRIENT MANAGEMENT G D Binford 71

O

ORGANIC FARMING C A Francis 77

ORGANIC MATTER

Principles and Processes M Schnitzer 85

Genesis and Formation K M Haider and G Guggenberger 93

Interactions with Metals N Senesi and E Loffredo 101

ORGANIC RESIDUES, DECOMPOSITION A J Franzluebbers 112

ORGANIC SOILS D L Mokma 118

OVERLAND FLOW T S Steenhuis, L Agnew, P Ge´rard-Marchant and M T Walter 130

OXIDATION–REDUCTION OF CONTAMINANTS C J Matocha 133

P

PADDY SOILS C Witt and S M Haefele 141

PARENT MATERIAL see PEDOLOGY: Basic Principles; FACTORS OF SOIL FORMATION: Parent Material

PEDOLOGY

Basic Principles M J Singer 151

Dynamic F C Ugolini 156

PEDOMETRICS I O A Odeh and A B McBratney 166

PENMAN, HOWARD LATIMER J L Monteith 176

PENMAN–MONTEITH EQUATION R Allen 180

PERCOLATION see HYDRODYNAMICS IN SOILS

PERMAFROST see POLAR SOILS

PERMEABILITY see HYDRODYNAMICS IN SOILS

PERSISTENT ORGANIC POLLUTANTS (POPS) see POLLUTANTS: Persistent Organic (POPs)

PESTICIDES R H Bromilow 188

PETROLEUM see HYDROCARBONS

pH N Bolan and K Kandaswamy 196

PHOSPHORUS IN SOILS

Overview J T Sims and P A Vadas 202

Biological Interactions M D Mullen 210

PHYTOTOXIC SUBSTANCES IN SOILS M Qadir, S Schubert and D Steffens 216

PLANT–SOIL–WATER RELATIONS R A Feddes and J C van Dam 222

PLANT–WATER RELATIONS C Gimenez, M Gallardo and R B Thompson 231

POISEUILLE’S LAW see HYDRODYNAMICS IN SOILS

POLAR SOILS J C F Tedrow 239

POLLUTANTS

Biodegradation P B Hatzinger and J W Kelsey 250

Effects on Microorganisms M E Fuller 258

Persistent Organic (POPs) D Johnson 264

POLLUTION

Groundwater H Rubin 271

Industrial S P McGrath 282

POLYMERS AND MICROORGANISMS M C Rillig 287

POORLY CRYSTALLINE ALLUMINOSILICATES see AMORPHOUS MATERIALS

POROSITY AND PORE-SIZE DISTRIBUTION J R Nimmo 295

POTASSIUM IN SOILS P M Huang, J M Zhou, J C Xie and M K Wang 303

PRECIPITATION, WATERSHED ANALYSIS J V Bonta 314

PRECISION AGRICULTURE see SITE-SPECIFIC SOIL MANAGEMENT

PREFERENTIAL FLOW see UNSTABLE FLOW; MACROPORES AND MACROPORE FLOW,

KINEMATIC WAVE APPROACHPRODUCTIVITY D L Karlen 330

PROFILE see MORPHOLOGY

PROTOZOA W Foissner 336

Q

QUALITY OF SOIL B J Wienhold, G E Varvel and J W Doran 349

R

RADIATION BALANCE J L Hatfield, T J Sauer and J H Prueger 355

RADIONUCLIDES see ISOTOPES IN SOIL AND PLANT INVESTIGATIONS

RAINFED FARMING see DRYLAND FARMING

RANGE MANAGEMENT G L Anderson 360

RECYCLING OF ORGANIC WASTES see POLLUTANTS: Biodegradation

REDISTRIBUTION see WATER CYCLE

REDOX POTENTIAL R D DeLaune and K R Reddy 366

REDOX REACTIONS, KINETICS P S Nico and S Fendorf 372

REMEDIATION OF POLLUTED SOILS E Lombi and R E Hamon 379

REMOTE SENSING

Organic Matter D K Morris, C J Johannsen, S M Brouder and G C Steinhardt 385

Soil Moisture T J Jackson 392

RHIZOSPHERE A C Kennedy and L Z de Luna 399

RICHARDS, LORENZO A W R Gardner 407

ROOT ARCHITECTURE AND GROWTH L E Jackson 411

ROOT EXUDATES AND MICROORGANISMS B-J Koo, D C Adriano, N S Bolan and C D Barton 421

SALINATION PROCESSES I Shainberg and G J Levy 429

SALINITY

Management D Hillel 435

Physical Effects D Russo 442

SALT BALANCE OF SOILS see SALINATION PROCESSES

SALT-AFFECTED SOILS, RECLAMATION R Keren 454

SAND DUNES H Tsoar 462

SATURATED AND UNSATURATED FLOW see HYDRODYNAMICS IN SOILS;

VADOSE ZONE: Hydrologic Processes

SCALING

Physical Properties and Processes G Sposito 472

Transport Processes R P Ewing 477

SEPTIC SYSTEMS R L Lavigne 485

SHIFTING CULTIVATION R Lal 488

SITE-SPECIFIC SOIL MANAGEMENT C J Johannsen and P G Carter 497SLASH AND BURN AGRICULTURE see SHIFTING CULTIVATION

SLUDGE see WASTE DISPOSAL ON LAND: Liquid; Municipal

SODIC SOILS G J Levy and I Shainberg 504

SOIL–PLANT–ATMOSPHERE CONTINUUM J M Norman and M C Anderson 513SOLUTE TRANSPORT M C Sukop and E Perfect 521

SORPTION

Metals D L Sparks 532

Organic Chemicals B Xing and J J Pignatello 537

Oxyanions C P Schulthess, H Wijnja and W Yang 548

SORPTION–DESORPTION, KINETICS D L Sparks 556

SPATIAL PATTERNS J H Go¨rres and J A Amador 562

SPATIAL VARIATION, SOIL PROPERTIES R Webster 1

SPECIFIC SURFACE AREA K D Pennell 13

STATISTICS IN SOIL SCIENCE R Webster 19

STERILIZATION see DISINFESTATION

STOCHASTIC ANALYSIS OF SOIL PROCESSES D Russo 29

STRESS–STRAIN AND SOIL STRENGTH S K Upadhyaya 38

STRUCTURE V A Snyder and M A Va´zquez 54

SURFACE COMPLEXATION MODELING S Goldberg 97

SUSTAINABLE SOIL AND LAND MANAGEMENT J L Berc 108

SWELLING AND SHRINKING D Smiles and P A C Raats 115

T

TEMPERATE REGION SOILS E A Nater 125

TEMPERATURE REGIME see THERMAL PROPERTIES AND PROCESSES

TENSIOMETRY T K Tokunaga 131

TERMITES see FAUNA

TERRA ROSSA see MEDITERRANEAN SOILS

TERRACES AND TERRACING G R Foster 135

TESTING OF SOILS A P Mallarino 143

TEXTURE G W Gee 149

THERMAL PROPERTIES AND PROCESSES D Hillel 156

THERMODYNAMICS OF SOIL WATER P H Groenevelt 163

TILLAGE see CONSERVATION TILLAGE; CULTIVATION AND TILLAGE; ZONE TILLAGE

TILTH D L Karlen 168

TIME-DOMAIN REFLECTOMETRY G C Topp and T P A Ferre´ 174

TROPICAL SOILS

Arid and Semiarid H C Monger, J J Martinez-Rios and S A Khresat 182

Humid Tropical S W Buol 187

U

UNSTABLE FLOW T S Steenhuis, J-Y Parlange, Y-J Kim, D A DiCarlo, J S Selker, P A Nektarios,

D A Barry and F Stagnitti 197

URBAN SOILS J L Morel, C Schwartz, L Florentin and C de Kimpe 202

V

VADOSE ZONE

Hydrologic Processes J W Hopmans and M Th van Genuchten 209

Microbial Ecology P A Holden and N Fierer 216

VIRUSES see BACTERIOPHAGE

VOLCANIC SOILS G Uehara 225

W

WAKSMAN, SELMAN A H B Woodruff 233

WASTE DISPOSAL ON LAND

Liquid C P Gerba 238

Municipal D A C Manning 247

WATER AVAILABILITY see PLANT–SOIL–WATER RELATIONS

WATER CONTENT AND POTENTIAL, MEASUREMENT G S Campbell and C S Campbell 253WATER CYCLE D K Cassel and B B Thapa 258

WATER EROSION see EROSION: Water-Induced

WATER HARVESTING D Hillel 264

WATER MANAGEMENT see CROP WATER REQUIREMENTS

WATER POTENTIAL D Or, M Tuller and J M Wraith 270

WATER RETENTION AND CHARACTERISTIC CURVE M Tuller and D Or 278WATER TABLE see GROUNDWATER AND AQUIFERS

WATER, PROPERTIES D Hillel 290

WATER-REPELLENT SOILS J Letey 301

WATERSHED MANAGEMENT M D Tomer 306

WATER-USE EFFICIENCY M B Kirkham 315

WEED MANAGEMENT D D Buhler 323

WETLANDS, NATURALLY OCCURRING E K Hartig 328

WIDTSOE, JOHN A AND GARDNER, WILLARD G S Campbell and W H Gardner 335WIND EROSION see EROSION: Wind-Induced

WINDBREAKS AND SHELTERBELTS E S Takle 340

WOMEN IN SOIL SCIENCE (USA) M J Levin 345

WORLD SOIL MAP H Eswaran and P F Reich 352

Z

ZERO-CHARGE POINTS J Chorover 367

ZONE TILLAGE J L Hatfield and A T Jeffries 373

Table of Contents, Volume 1

A 1

Acid Rain and Soil Acidification 1

Introduction 1Acid Rain 1Atmospheric Transport, Secondary Chemistry, and Acid Rain 2Dry oxidation of sulfur and nitrogen oxides 2Wet oxidation of sulfur 2Acid Soil 3Sources of Acids in Soils 4Internal Acid Production in Soils 4Carbonic and organic acid production 4Nitrogen accumulation and transformations 5Assimilation of Nutrients by Vegetation 5Deposition of Nitrogen Species and Nitrogen Transformations 5Addition of Dissolved Strong Acids Through Acid Deposition 5Observations of Changes in Soil Acidification due to Acid Deposition 5Proton Sinks and Buffer Ranges 6Carbonate and Silicate Buffers 7Cation Exchange Buffer 7Aluminum and Iron Buffer 8Proton Adsorption Reactions 9Acid Sources and Sinks: Input-Output Relationships and the

Calculation of Proton Balances 9Acidification, Ecosystem Stability and Global Change 9Further Reading 11

Acidity 11

Introduction 11Processes Generating Acidity in Soils 12Acid Drainage 12Acid Precipitation 12Elemental Cycling 13Fertilizer Reactions 14Measurement and Effects of Soil Acidity 15Amelioration of Soil Acidity 16Further Reading 17

Aeration 17

Introduction 17Soil-Air Composition 17Gas Exchange Mechanisms 18Diffusion 18Convection 18Gas Reactions 19Respiration 19Oxidation-Reduction Processes 19Production and Consumption of Other Gases 19Aeration Requirements 20Plants 20Remediation of Contaminated Soils 20Summary 20Further Reading 21

Aggregation 22

Microbial Aspects 22Introduction 22Microorganisms and Aggregate Formation 22

Protection of Organic Matter Conferred by Soil Aggregates 26Soil as a Spatially Continuous Medium 27List of Technical Nomenclature 28Further Reading 28Physical Aspects 28Forces on Soil Particles 29Aggregate Physical Properties and their Measurement 31Basic Properties 31Size and Stability 32Fundamentals 32Commonly used methods 32Miscellaneous methods 33Issues of general importance 33Representation and Interpretation 33Summary 34Further Reading 34

Agroforestry 35

Introduction 35Emergence of Agroforestry as a Land-Use Approach 35Agroforestry Systems 36Examples of Common Agroforestry Systems 38Improved Fallow 38Alley Cropping 38Homegarden, Shaded-Perennial, and Multistrata Systems 39Silvopastoral Systems 40Agroforestry Applications for Soil Conservation and Reclamation 41Other Agroforestry Applications 41Agroforestry and Ecosystem Services 42Soil Productivity and Protection 42Carbon Sequestration 42Agroforestry Research 43Future Directions 43Acknowledgments 43List of Technical Nomenclature 44Further Reading 44

Alluvium and Alluvial Soils 45

Introduction 45Alluvium 45Composition 45Texture 45Landforms 46Alluvial Soils 47Recent Alluvial Soils 47Older Alluvial Soils 47Classification 48Human Use of Alluvial Soils 48List of Technical Nomenclature 49Further Reading 49

Aluminum Speciation 50

Introduction 50Inorganic Aluminum Species in Soil Solution 50Organic Complexes of Aluminum 51Determining Aluminum Speciation in Experimental Samples 53Computational Methods 53

Fractionation Based on Size, Charge, and Reactivity 53Speciation Using More Direct Analytical Methods 54Further Reading 56

Ammonia 56

Introduction 56Chemical Reactions of Ammoniacal N 57Ammonia-Ammonium Equilibrium 57Retention of Ammonia by Soils 57Retention and Loss of Surface-Applied Ammoniacal N in Soils 59Reactions of Urea in Soils 59Environmental Conditions and Ammonia Formation 60Urea concentration 60Soil pH and H+ buffering capacity 61Factors affecting the rate of urea hydrolysis 61Soil urease concentration 61Urea concentration 62Soil temperature 62Soil water content 62Soil pH 62Reactions of NH4+-N Applied to Calcareous Soils 62List of Technical Nomenclature 63Further Reading 63

Amorphous Materials 64

Introduction 64Occurrence in Soils 64Identification 65Structure and Charge 67Chemisorption and Ligand Exchange 68Reaction with Soil Organic Matter 70Aluminum Solubility 70Physical Properties 71Further Reading 71

Anaerobic Soils 72

Physical Characteristics 72Biological Characteristics 73Chemical Characteristics 73Morphological Characteristics of Wetland Soils 74Biogeochemical Characteristics 74Microbial Respiration 75Agronomic, Ecologic, and Environmental Significance 77Further Reading 78

Applications of Soils Data 78

Introduction 78Development of Interpretations in the USA 78Interpretations Beyond Agriculture 80Today’s Interpretive Categories 81National Inventory Groupings 81Land-Use Planning 81Farmland 81Rangeland 81Forest Land 81Windbreaks 81Recreation 81Wildlife Habitat 83Construction Materials 83Building Sites 83

Uses of Soils Data and Interpretations 83Federal and State Programs 83State and Local Planning 84Natural Resource Management 84Land Appraisal and Assessment 84Engineering and Construction 86Hazardous Waste, Brownfields, and Remediation 86Research and Analyses 86Conclusion 88Further Reading 88

Archaea 88

Introduction 88Archaeal Evolution 89The Archaeal Cell 89Three Archaeal Groups 90Extreme Halophiles 90Methanogens 91Hyperthermophiles 92Psychrophiles 93Thermoplasma 93Biotechnological Use of Extremoenzymes 93Further Reading 94

Archeology in Relation to Soils 95

Introduction 95Pedostratigraphy and the Archeological Record 95Archeological Soil Chemistry 97Soil as a Resource 98Further Reading 101

B 103

Bacteria 103

Plant Growth-Promoting 103Introduction 103Plant Growth-Promoting Bacteria in Agriculture and the Environment 103Endophytic PGPB 108Biocontrol of Phytopathogens 108Mechanisms Employed by Biocontrol-PGPB to Control

Phytopathogens 109Production of Antibiotics 109Production of Siderophores 110Production of Small Molecules 110Production of Enzymes 110Competition and Displacement of Pathogens 111Modification of Plant Metabolism 112Induced and Acquired Systemic Resistance 112Modification of Plant Ethylene Levels 112Prospects for Improving PGPB by Genetic Manipulation 112PGPB Inoculants 112Conclusions and Prospects 113Further Reading 114Soil 115Introduction 115Bacterial Diversity 115The Microbe as the Scale of Study 116Two Basic Survival Strategies 117

Avoidance 117Stress Tolerance 118Water Availability 118Extracellular Polysaccharide Production 118Biofilms 119Competition for Resources 119Cooperation Among Bacteria 120Siderophores 120Quorum-Sensing 120Death 121Summary 121Further Reading 122

Bacteriophage 122

Introduction 122Why Soil Bacteriophage? 122Ecologic Role of Viruses in Microbial Communities 123Bacteriophage Contain Genetic Elements that Can Increase Host

Fitness: Bacteriophage Conversion 123The Role of Phage in Horizontal Gene Transfer and Bacterial

Evolution 123Evidence for Natural Transduction in Microbial Communities 124Cultivation-Independent Investigation of Soil Viral Communities 125Microscopy of Soil Viruses 125Genomic Approaches to Viral Diversity 127Summary 128List of Technical Nomenclature 128Further Reading 128

Biocontrol of Soil-Borne Plant Diseases 129

Introduction 129Enhancement of Biocontrol by Agronomic Practices 130Crop Rotations 130Organic Amendments 130Biocontrol with Introduced Microbial Biocontrol Agents 131Selection, Evaluation, and Delivery of Microbial Biocontrol Agents 131Mode of Action of Biocontrol Agents 133Competition 133Antibiosis 133Parasitism 133Induced systemic resistance 134Plant growth-promoting rhizobacteria 134Future Prospects 134Conclusions 135Further Reading 135

Biodiversity 136

Introduction 136Diversity and Abundance 136Distribution 138Soil Biodiversity and Ecosystem Functioning 139Global Change and Impacts on Soil Biodiversity 140Sustaining Soil Biodiversity 141Further Reading 141

Buffering Capacity 142

Introduction 142The Samovar Analogy for Buffering in Soils 142Buffering of Soil Acidity 143Dissolution and Precipitation of CaCO3 and Al(OH)3 144

Buffering of Soil Oxidation-Reduction Status 146Buffering of Ion Activities via Dissolution-Precipitation, Ion Exchange, andLigand Complexation 146Further Reading 147

C 149

Calcium and Magnesium in Soils 149

Introduction 149Input to Soils 149Reactions in Soils 151Modeling the Dissolution Reactions of Calcium and Magnesium

Compounds in Soils 151Plant Requirements and Deficiency Symptoms 152Plant Uptake 153Interactions with Other Nutrients 153Animal Requirements 153Further Reading 154

Capillarity 155

Introduction 155Liquid Properties 155Surface Tension 155Contact Angle 155Curved Surfaces and Capillarity 156The Capillary Rise Model 157Capillarity in Soils 158Capillarity in Angular Pores 158Dynamic Aspects of Capillarity 159Dynamics of Capillary Rise 159Dynamic Contact Angle 160Heterogeneous Surfaces and Microscale Hysteresis 161Contact Angle on Chemically Heterogeneous and Rough Surfaces 161Hysteresis 163Further Reading 163

Carbon Cycle in SoilsDynamics and Management 164

Dynamics and Management 164Introduction 164Fluxes 166Soil-Forming Factors 166Functions 166Regulation of Soil Organic Carbon Dynamics 167Composition of Soil Organic Carbon 168Management 168Further Reading 170Formation and Decomposition 170Introduction 170Sources of Carbon 170Aerobic Decomposition 171Anaerobic Decomposition 172Factors Controlling Decomposition 173Soil Organic Matter Formation and Turnover 174Further Reading 175

Carbon Emissions and Sequestration 175

Introduction 175Soils and Carbon-Cycling 175Controls on Emissions and Sequestration 176

Land Use and Land-Use Change 177Management Practices for Soil C Sequestration 178Regional and Country Estimates of C-Sequestration Potential 179List of Technical Nomenclature 179Further Reading 180

Cation Exchange 180

Introduction 180Cation Exchange Capacity 181Qualitative Description of Cation Exchange 182Properties of Ions 182Properties of Surfaces 183Properties of Solvents 183Quantitative Description of Cation Exchange 184Homovalent Binary Exchange 184Heterovalent Binary Exchange 185The Future of Cation Exchange 187List of Technical Nomenclature 188Further Reading 188

Chemical Equilibria 189

Introduction 189Chemical Equilibrium 189Kinetic Definition 189Free-Energy Definition 189Applicability of Chemical Equilibrium Principles to Soils 190Limitations to Equilibrium in Soils 190Soil Systems in Which Equilibrium Concepts May Apply 191Reasonable Expectations from Application of Equilibrium 191Predict endpoints of reactions 191Determine ionic activities in soil solution 191Calculating final conditions for systems that attain equilibrium rapidly 191Experimental Approach to Equilibrium in Soils 191System Variables 191Reactions and Associated Equilibrium Constants 191Equilibrium Modeling of Soil Systems 192Geochemical models 192Model inputs 192Application of Chemical Equilibrium to Soils: Examples 192Iron Oxides in Reduced Systems 192Manganese(III) Phosphate 193Calcite in Soils: Equilibrium versus Nonequilibrium 193The Outlook for Studying Chemical Equilibrium in Soils 193List of Technical Nomenclature 194Further Reading 194

Childs, Ernest Carr 195

Further Reading 198

Civilization, Role of Soils 199

Human Management of the Soil 199Historical Attitudes Toward the Soil 199Human Origins 200The Paleolithic Transformation 201The Agricultural Transformation 201Soil Husbandry and Ceramics 202From Rainfed to Irrigated Farming 203Silt and Salt in Ancient Mesopotamia 203The Sustainability of Egyptian Agriculture 203Further Reading 204

Principle of Domain 205Principle of Identity 206Principle of Differentiation 206Principle of Prioritization 207Principle of Diagnostics 209Principle of Membership 209Principle of Certainty 210Summary 210List of Technical Nomenclature 210Further Reading 210

Classification Systems 211

Australian 211Introduction 211History of General-Purpose National Soil Classifications 211The New National Classification 212Soil Classifications Used on Australian State and Regional Scales 213The Basis for State and Regional Soil-Classification Systems 213State and Regional Examples 213Special-Purpose Soil-Classification Systems 214Viticultural Soils 214Engineering Applications: Laying of Telecommunication Optical Fiber

Cables 214Future Directions 216Further Reading 216FAO 216Introduction 216The Development of the FAO Legend 1960-—1981 216Set 1 218Set 2 218Set 3 218Set 4 218Set 5 219Set 6 219Set 7 219Set 8 219The FAO Revised Legend 1981-1990 219The World Reference Base for Soil Resources 1981-1998 220Summary 222Further Reading 222Russian, Background and Principles 223Introduction 223Principles, Categories, and Classes in Major Classification Systems

Developed in Russia 223Early Systems 223NonOfficial Systems in the Second Half of the Twentieth Century 224Official Systems 224Classification and diagnostics of soils of the USSR - 1977 225Russian soil classification system - 1997 225Conclusion 227Further Reading 227Russian, Evolution and Examples 227Introduction 227Pre-Dokuchaev Period 228Agroproductive Soil Groups, Folk Soil Nomenclature, and First Scientific

Soil Classifications 228Dokuchaev’s Period 229Genetic Approach to Soil Classification 229Post-Dokuchaev Period 230Diversification of Classification Decisions 230Official Soil Classification and Unofficial (Authors’) Systems 232The Problem of Basic Substantive-Genetic-Soil Classification and the newRussian Classification 232Further Reading 235USA 235Introduction 235Soil Classification Criteria 236Soil Composition 236Genesis and Soil Taxonomy 237Climate Zones in Soil Taxonomy 238Structure and Nomenclature 240How it Works 240Example Profile 242Closing Thoughts 245List of Technical Nomenclature 245Further Reading 245

Clay Minerals 246

Introduction 246Major Element Composition of Clay Minerals 246Basic Structural Concepts 246Tetrahedra and Octahedra 246Representing Crystal Structures 247Tetrahedral and Octahedral Sheets 247Tetrahedral Sheet 247Octahedral Sheet 247Phyllosilicate Minerals Common In Soil Clays 2481:1-Type Minerals 2481:1 Layer structure 248Kaolinite 248Halloysite 2482:1-Type Minerals 2492:1 Layer structure 249Pyrophyllite 249Micas 249Vermiculites 251Smectites 251Chlorites 251Hydroxy-interlayered vermiculite and smectite 251Interstratification in phyllosilicates 252Palygorskite and sepiolite 252Other Minerals that Occur in Soil Clays 252Zeolites 253Allophane and Imogolite 253Aluminum Hydroxide Minerals 253Iron Oxide Minerals 253Manganese Oxide Minerals 253Titanium Oxide Minerals 253Carbonates, Sulfates, and Soluble Salts 253List of Technical Nomenclature 254Further Reading 254

Climate Change Impacts 254

Timescale for Change 255Climate Change Impacts on Soil Water and Soil Temperature 255Soil Water 255Soil Temperature 257Changes in Soil-Forming Processes and Properties 257Soil Organic Matter 257Soil Structure 258Soil Fauna and Soil Flora 258Acidification and Nutrient Status 258Changes in Land-Degradation Processes 259Soil Erosion 259Desertification 259Salinization 260Climate Change Impacts on Soil Functions 260Further Reading 262

Climate Models, Role of Soil 262

Introduction 262Approaches to Modeling SOC Dynamics for the Study of Climate Change 262Process-Based, Multicompartment Models of SOC Dynamics 263Cohort Models Describing Decomposition as a Continuum 263Food-Web Models 263Factors Affecting the Turnover of Soil Organic Carbon in Models 263Model Performance 264Models Used to Study the Impacts of Climate Change 264Climate Models with Coupled Description of Biospheric Carbon Feedbacks 264.List of Technical Nomenclature 267Further Reading 267

Cold-Region Soils 268

Introduction 268Definition of Cold Soils 268Characteristics and Genesis of Cold-Region Soils 269Physical Properties 269Boreal soils 269Arctic soils 269Alpine and high arctic soils 269Morphological Properties 270Biological and Chemical Properties 271Alpine and Plateau Regions 272Vegetation and Fire 273Land Use of Cold-Region Soils 273Engineering 274Agriculture Development 274Further Reading 275

Colloid-Facilitated Sorption and Transport 276

Introduction 276Nature and Stability of Soil Colloids 276Colloid Transport in Porous Media 279Factors Influencing Colloid Release 280Factors Influencing Colloid Deposition 281Colloid-Facilitated Transport of Contaminants 283Further Reading 284

Compaction 285

Introduction 285Factors and Processes Affecting Distribution and Intensity of Compaction 285

Compaction under Running Gear 285Loading Characteristics of Individual Wheels or Caterpillar Tracks 285Field Traffic Intensity and Distribution 286Soil Compactibility 287Effects on Soil Physical and Mechanical Properties 287Bulk Density, Porosity, and Packing State 287Hydraulic Properties 287Aeration Characteristics 288Strength Characteristics 288Compaction in Crop Production 288Effects on Germination and Establishment 289Effects on Root Growth and Distribution 289Effects on Plant Growth and Yield 289Interactive Crop Responses to Compaction and Fertilizer Application 289Crop Responses to Subsoil Compaction 289Modeling of Crop Responses to Soil Compaction 290Effects on Environmental Components 290Techniques for the Reduction of Compaction 292Amelioration of Compacted Soils 293Further Reading 293

Compost 294

Introduction 294Compost Production 294Compost Application and Incorporation 295Compost-Soil Interactions 296Physical Effects 296Chemical Effects 297Biological Effects 299List of Technical Nomenclature 300Further Reading 300

Conditioners 301

Introduction 301Early Use of Mineral and Organic Materials 301Use of Waste Materials as Conditioners 302Advent of Synthetic Conditioners 302Hydrogels and Super Water-Absorbent Polymers 303Recent Advances Using Polyacrylamide 304Further Reading 305

Conservation Tillage 306

Introduction 306Evolution of Conservation Tillage Systems 306Defining Conservation Tillage 307Variants of Conservation Tillage 307Common Types of Conservation Tillage Practices 308Constraints to the Adoption of Conservation Tillage Practices 308Climate and Soil 308High Levels of Crop Residue 308Mixed Cropping Systems 309Beneficial Influence of Conservation Tillage 309Improving Soil Quality and Health 309Enhancing Soil Organic Matter Storage 309Reducing Soil Erosion and Environmental Risk 310Tillage Costs 310Further Reading 310

Cover Crops 311

Introduction 311

Seeding and Husbandry 313Role in Soil Quality Improvement 314Role in Soil Erosion Control 315Nature of Soil Erosion 315Runoff and Erosion Control 316Perspective 316Further Reading 317

Crop Rotations 318

Introduction 318Soil Fertility and Crop Yields 319Cultural Management 320Pest Management with Rotations 320Economic Diversity 321Future Perspectives 321Further Reading 322

Crop Water Requirements 322

Introduction 322Crop Evapotranspiration 323Crop Coefficients 324The Single-Crop Coefficient Approach 325

Kc Adjustment for Climate 330

Kc Adjustment for Nonpristine Conditions 330The Dual-Crop Coefficient Approach 330

Kc for Nonpristine and Unknown Conditions 332Irrigation Water Requirements 332Summary 332List of Technical Nomenclature 333Further Reading 334

Crop-Residue Management 334

Introduction 334Conservation, Carbon Cycle, Soil Organic Matter and Carbon Sinks 334Crop Residues and Nutrient Cycling 335Factors Controlling Residue Decomposition and Soil Quality 336Crop Residues: Social and Environmental Benefits 336Crop Residues, Research and Global Change 337Summary 337Further reading 338

Crusts 339

Biological 339Introduction 339Species Composition and Growth Forms 339Ecological Roles 341Carbon Fixation 341Nitrogen Fixation 341Dust Trapping 343Effects on Vascular Plants 343Nutrient Levels in Vascular Plants 343Soil Hydrology and Stabilization 343Effects of Disturbance 344Species Composition 344Water Erosion 344Wind Erosion 344Nutrient Cycles 345Albedo 345

Recovery from Disturbance 345Natural Recovery Rates 345Assisted Recovery 345Conclusion 345Further Reading 347Structural 347Introduction 347Crust Types and Morphology 348Factors Governing Crust Formation 349Rainstorm Characteristics 349Soil Properties 351Hydrologic Impact of Crusts 351Infiltration - Developed Crusts 352Infiltration - Developing Crusts 352Numerical Infiltration Models for Developing Crusts 353Agronomic Importance of Crusts 354Further Reading 355

Cultivation and Tillage 356

Introduction 356Goals of Soil Tillage 356Main Types of Tillage Tools 357Moldboard Plow 357Applications 357Disadvantages and limitations 357Chisel Plow 358Applications 358Disk Harrow 358Toothed Cultivator 359Subsoiler 359No-tillage 359Basic Tillage Operations 360Types of Tillage Systems 360List of Technical Nomenclature 361Further Reading 361

D 363

Darcy’s Law 363

Introduction 363Water-Saturated Soil Conditions 363Validity of Darcy’s Equation 364Solving Saturated-Flow Problems 366Water in Unsaturated Soils 366Solving Unsaturated-Flow Problems 368List of Technical Nomenclature 368Further Reading 369

Degradation 370

Introduction 370Factors and Processes Affecting Degradation of Soils 370Types of Soil Degradation 371Assessment of Degradation 371Approaches 371Potentials and Limitations 373Degree and Impact of Degradation 374Degree of Degradation 374Rate of Soil Degradation 375Impact of Degradation 375Preventing and Combating Degradation 375

Introduction 378Definitions and Pathways 378Organisms and Substrates 378Denitrification 378Nitrifier Denitrification 379Environmental Factors 380Organic C Availability 380Controls on O2 Availability 380Nitrate Supply 381Temperature 381

pH 381Conclusion 381Further Reading 382

Desertification 382

Introduction 382The Role of Drought 383Primary Production and Carrying Capacity 384Soil Degradation and Rehabilitation 385Potentialities and Problems of Irrigation 385Social Factors 386Monitoring Desertification 386The Role of Climate Change 387Overview 387Further Reading 388

Diffusion 389

Introduction 389How Diffusion Occurs 389Fick’s Laws 390Initial and Boundary Conditions 390Components of the Diffusion Coefficient in Soil 390Diffusion and Geometry 391Some Useful Analytical Solutions for Various Geometries 391Diffusion from a Semiinfinite Medium 391Diffusion in a Cylinder 392Diffusion in a Sphere 392Simple Model for Various Geometries 392Applications in Soil Science 393Plant Nutrition 393Kinetics of Potassium Release From Clays 393Gaseous Diffusion 393Leaching 393List of Technical Nomenclature 393Further Reading 394

Disinfestation 394

Introduction 394Principles of Soil Disinfestation 395Methods of Soil Disinfestation 395Physical 395Chemical 396Methyl bromide 396Metham sodium 396Dazomet (3,5-dimethyltetrahydro-1,3,5,(2H)-thiodiazinothione) 396Other fumigants and mixtures 396Application 396

Soil Solarization 397Principles of soil solarization 397Soil heating: simulation models for the prediction of soil temperatures 398Combining Disinfestation Methods 398Benefits and Limitations 399The MBr Crisis and Its Implications 399Further Reading 399

Dissolution Processes, Kinetics 400

Introduction 400Rates and Limits of Element-Cycling 401Kinetics of Proton- and Ligand-Promoted Mineral Dissolution 401Metal-Promoted Mineral Dissolution 403Reductive Dissolution of Minerals 404Dissolution of Metal Surface Precipitates 404The Good and Bad of Dissolution Kinetics 407List of Technical Nomenclature 408Further Reading 409

Drainage, Surface and Subsurface 409

Introduction 409Hydrology and Drainage 410Accelerated Drainage 410Surface Drainage Principles and Practices 410Subsurface Drainage Principles and Practices 411Recent Innovations in Drainage Practice 412Further Reading 413

Dryland Farming 414

Introduction 414Definition 414World Scope of Dryland Farming 414Major Dryland Farming Issues 415Dryland Farming Management Techniques 415Fallowing 415Water Capture Management 416Water Retention Management 416Efficient Water Use by Crop Plants 417Conclusion 417Further Reading 417

E 419

Edaphology 419

Introduction 419Edaphic Properties 419Edaphic Factors Affecting Water and Air 420Edaphic Factors Affecting Plant Nutrients 421Edaphic Factors Affecting Root Growth 423Research 424List of Technical Nomenclature 424Further Reading 425

Electron-Spin Resonance Spectroscopy 426

Introduction 426Basic Principles 426The Resonance Phenomenon 426Spectral Parameters 426Instrumentation and Methodology 427The Instrument and the Experiment 427Sample Preparation 428Sensitivity and Resolution 429

Organic Free Radicals in Soil Humic Substances 430ESR Spectra and Parameters 430Interpretation of ESR Parameters 431Factors Affecting ESR Parameters of Humic Substances 431Structural Implications 431Interactions of Humic Free Radicals with Organic Chemicals and MetalIons 432Paramagnetic Transition Metal Ions in Soil Constituents 432ESR Spectra and ESR Parameters 432Ferric iron 433Divalent copper 434Vanadyl ion 435Divalent manganese 435Spin-Derivatization Studies 435Spin-Labeling and Spin-Trapping 435Metal Spin Probes 435Complexation chemistry of humic substances 435Ion exchange on layer silicates 436Chemisorption on mineral surfaces 436Thermodynamic constants from ESR parameters 436List of Technical Nomenclature 436Further Reading 437

Energy Balance 438

Introduction 438The Energy Input From the Sun 438Energy Balance of a Planet Without Atmosphere 438Energy Balance of the Earth’s Surface 438Anthropogenic Change of the Energy Balance 441Further Reading 441

Environmental Monitoring 441

Introduction 441Why Monitor Soils? 442The Starting Point 443Soil-Monitoring Networks 444Protocols 444Monitoring Sites 444Soil Sampling 446Quality Control 447Summary 447Further Reading 447

Enzymes in Soils 448

Introduction 448Spatial Distribution of Enzymes in Soils 449Extracellular Enzyme Stabilization in Soil Matrix 449Microscale Distribution 449Macroscale Distribution 450Methods of Studying Enzyme Activities in Soils 450Enzyme Kinetics 451Soil-Quality Indicators and Technologies 452Sensitivity to Soil Management and Ecosystem Stress 452Ecological Dose Value 454Detoxification of Polluted Soils 454Summary 455Further Reading 455