Lal R., Shukla M.K. Principles of Soil Physics
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mathematical representation of, 482–484
miscible displacement, 474
nondimensional variables for equa- tions of, 497
nonequilibrium, 488
one-dimensional, 490–491
processes of, 466–468
relations between dispersion coefficient and pore water velocity in, 481
sorption phenomenon in, 484–486
step input experiments for, 493–495
two-region anion exclusion model for, 491–492
two-region nonequilibrium model for, 489–491
two-site nonequilibrium model for, 491–492
Solute transport equation, 483
Sorption, 477, 478
models of, 485–486, 487
in solute transport, 484–486
in two-site nonequilibrium transport model, 493
Sorptivity, 416
Sources, 575
Spatial fractals, 133
Specific gravity (G
s
), 21
Specific humidity, 269
Specific surface area, 60
of clay minerals, 72
importance of knowing, 47
indices of, 47–48
particle geometry for, 48–50
using adsorption isotherms to deter- mine, 50–52
Specific water capacity, 344
Spherical particles, specific surface area of, 49–50
Sphericity, 47
Spider gauge, 275
“Spirit” thermometer, 516
Sprinkler method, 394–395
for testing water infiltration limits, 406
Stability against water or wind method, 127
Static penetration test, 215
Stationary liquid method, 583–584
Steady flow (v) equation, 373–374
Steady state methods
for measurement of K
T
, 544
for measuring soil’s hydraulic function, 391
Stefan-Boltzmann equation, 519–520
Stefan-Boltzmann law, 531
Step input experiments, 493–495
Stern model, 60–61
Sticky limit, 238
Strain (ε)
longitudinal (ε), 192
in Poisson’s ratio (v), 194
Index 674
relationship to stress in soil, 196–197
rhelogical models for, 189–191
shear (γ), 192
time-dependent, 193
in Young’s modulus, 194
Strain hardening, 195–196
Stress (a)
acting inside soil body, 202
normal (a), 192
in Poisson’s ratio (v), 194
relationship to strain in soil, 196–197
rhelogical models for, 189–191
tangential (τ), 192
time-dependent, 193
in Young’s modulus, 194
Stokes law, 38, 39, 40
assumptions of, 41
Storage pores, 152, 154
Structural crusts, 167
Structural degradation, environmental effects of, 165, 166, 167, 168
Structural form, 97
Structural pores, 94
Structural porosity, 150
Structural resiliency, 132–133
Structural stability
bonding agents for, 110–114
defined, 110
methods of determining, 127
Structured soils, 122
Structured water, 70
Structureless soils, 122
Subirrigation, 589–590
Sublimation, 535
Submergence potential, 324
Subsidence, 9
Subsoil alleviation, 219, 221
Subsoiling, 243
Subsurface flow short-circuiting, 632–633
Suction head, 445
Sulfuric acid solutions, 688
Summation curve, 42, 44, 128
Surface aggregation ratio, 130
Surface area per unit bulk volume (a
b
), 47
Surface area per unit mass (a
m
), 47
Surface area per unit volume (a
v
), 47
Surface runoff, 406
Surface seal, 169, 170
Surface tension, 158–159, 258–259, 527, 680, 684
Swelling, 116, 637–644
clay and, 639–640
Index 675
cross-linking particles and, 67
curtailing diffused double-layer repulsion in, 68
defined, 66
effect of exchangeable cations on, 66–67
flow in, 642–643
interlattice, 66
interparticle, 66
measurement of, 643–644
models for, 641
pressure potentials in, 640–641
process of, 67
ratio of, 66
stages of, 641–642
Swelling index, 66
Swelling pressure, 638–639
Synthesis cracks, 634–635
Tangential stress (τ), 192, 193
relationship to normal stress (a), 198
Temperature, 515, 684
conversion from one scale to another, 516
and gravelly soils, 617–618
Remote Sensing Thermometer, 519–520
scales for, 516–517
thermocouple, 519
as thermodynamic property, 520–521
Temporary binding agents, 111
Tensile deformation, 204
Tensile strength, 203–204
Tensiometers
absolute pressure (P) of, 335
components of, 326
defined, 326
in internal drainage method, 395
limitations of, 329, 333–335
for measuring matric potential (Φ
m
), 333–335
mercury manometer, 326–328
types of, 327
vacuum gauge, 327, 328–329
Tension infiltrometer, 428
Terminal velocity, 39
Terzaghi’s effective stress equation, 202
Textural classes, 42, 43
Textural pores, 94
Textural porosity, 150
Texture
agricultural applications of, 84
effect on field moisture capacity (FC), 290
impact on soil, 82–83
soil properties and processes affected by, 83
Index 676
soil structure index based on, 131
Thawing, 625.
See also Frozen soils
and soil physical properties, 630–632
Thermal conductivity (K
T
), 308–309, 533, 618
of certain metals, 534
defined, 538
effective, 544
of gases, 538
measurement of, 543–545
merits and limitations of, 313
of soil particles, 539
Thermal diffusivity, 539
Thermal expansion, 516
Thermal infrared radiation, 310
Thermalization, 301
Thermal radiation monitoring, 519
Thermic soils, 531
Thermistor, 519
Thermocouples, 519
for the measurement of K
T
, 544
Thermodynamic potential, 61
Thermodynamic properties, 520–521
Thermodynamics
first law of, 521–522
second law of, 522–523
third law of, 522–523
zeroth law of, 521–522
Thermodynamic temperature, 520
Thermoelectric effect, 519
Thermogravimetric method, 299
merits and limitations of, 313
Thermometric liquid, 516
Thermoscope, 515–516
Third law of thermodynamics, 522–523
Thixotropic fluids, 267
Thorburn subsoiling test, 127
Tillage, 118–120, 586
conservation, 458
defined, 456
effect on aggregation, 118–120
effect on soil temperature, 546
effects on soil structure, 137
methods of, 459, 546
reduction of soil water evaporation, 456–457
and soil plasticity, 243–245
and water infiltration, 429, 432–433
Tilth
defined, 236
making objective classifications for, 236
Index 677
production of, 243
and soil consistence, 233, 236
Time domain reflectometry (TDR), 307–308
merits and limitations of, 313
Time moment analysis, 501
Tortuosity, 468
gas (ξ
g
), 368
of soil pores, 467
water (ξ
θ
), 368
Total porosity (f
t
), 22, 155
Total soil-moisture potential (Φ
t
)
components of, 323–331
under field conditions, 331–333
units of measurement for, 323
Trace gases, importance in Earth’s atmosphere, 559
Transient binding agents, 111–113
Transient evaporation, 446–447
Transient methods
for measurement of K
T
, 544
for measuring soil’s hydraulic function, 391–392
Transmission pores, 152, 154
formation of, 155
Transmission technique, 215
Transverse dispersion, 472
Travel time analysis, 501
Triaxial shearing test, 201–202
Tropical soils, measuring structural sta- bility of, 131
Turbidity/slaking test, 127
Turbulence, 468
Two parallel plate model, 641
Two-region anion exclusion model, 491–492
Two-region model (TRM) parameters, 503–507
Two-site nonequilibrium transport model, 491–492
Unconfined compression test, 202
Uniformity coefficient, 44
Unit conversion factors, 672
Unit conversions, 676
for soil and water potential, 679
Unsaturated flow
application of continuity equation to, 384
application of Richards equation to, 386
flux density in, 382
functions of, 379
mechanisms of, 380–382
versus saturated flow, 381
across soil core, 382
total outflow rate of, 385
using Darcy–Buckingham equation to determine, 382–383
Index 678
zone of, 379–380
Unsaturated hydraulic conductivity, 383–384
calculating parameters of, 400–401
calculating with VG equation, 401–402
empirical approaches to estimating, 399–402
measuring with Boltzmann transform method, 393–394
measuring with in situ methods, 394–396
measuring with laboratory methods, 391–393
measuring with soil water retention methods, 396–397
model for predicting, 397–399
relationship to soil porosity, 389–391
Upper plastic limit, 238
in Casagrande test, 242
in Drop-Cone test, 242
indirect methods for measuring, 242–243
Upscaling, 657
Unsteady infiltration, 425–426
Vacuum gauge tensiometer, 327, 328–329
Vadose zone, 379–380, 579
van der Waals forces, 59
colloidal stability and, 172
equation for attractive energy due to, 172
types of, 98
Vane shear test, 203
Vapor density, 269
Vapor in saturated air, 684
Vapor pressure, 268–269, 684
estimating, 411
Vapor-wetting front, 409
Vegetation, 523–524
Vegetative mulch, 453, 454, 456
Vertical flow, 374–375
Vertical infiltration, 416–417
Vertisols, 638
Vesicular-arbuscular (VA) mycorrhizal fungi, 112–113
Viscoelastic fluids, 267
Viscoelastic soil, 197
Viscosity, 527
of fluids, 265–266
kinematic, 265–266
Newton’s law of, 266, 357
of water, 528
Viscosity coefficient, 266
Viscous flow, 237
versus plastic flow, 247
upper limit of, 238
Visible and near infrared spectrum, 310
Void ratio (e), 155, 205
Index 679
range of, 25
Volume displacement method, 311–312
Volumetric compression, measuring resistance to, 197
Volumetric flow rate, 385
equations for, 358
using Poiseulle’s law for, 389
Volumetric heat capacity (C
y
), 523
Volumetric inflow rate, 385
Volumetric soil moisture content (Θ), 23–24, 25
Warrick similarity analysis, 658
Water.
See also Soil water
boiling point of, 268–269, 516
change from liquid to vapor, 268
density and viscosity of, 528
density of, 681
entropy of, 257
evaporation from soil. See Soil water evaporation
flux density of, 471
freezing point of, 516
global distribution of, 255, 256
global transfer rates of, 270
hydrologic cycle of, 269–270
large specific heat of, 98
lysimetric analysis of, 272
measuring in unit quantities, 337
measuring of runoff, 272, 276–278
precipitation of, 272
properties of, 256–269
redistribution into soil, 426–427
six phase changes of, 534–535
soil as reservoir of, 271
solute-free, 466
as soil moisture content. See Soil moisture content
total potential of, 356
transport to soil surface, 441
viscosity of, 682
types of, 255, 256
Water absorption, 68–69
Water absorption isotherms, 68, 69
Water adsorption, 69–73
Water deficit, 296
Water desorption method, 158–160
Water film theory, 236–237
Water flow, 9
capillary bundle concept of, 356–357
through homogeneous soil profile, 410–411
horizontal, 371
importance of knowing, 355
Index 680
laminar, 359–360
land use effects on, 508
and matric suction (Φ
m
), 380–382
principles of, 356–361
in saturated soils. See Saturated flow
steady, 373
through 3-dimensional space, 370–372, 384
upward, 445
in unsaturated soils. See Unsaturated flow
using Darcy’s law to determine, 357–361
vertical, 371
at wetting front, 407–412
Water infiltration
calculating depth of, 433
calculating rate of, 433
comparisons of equations for, 421
conceptual models for predicting rates of, 412–418
into crusted soils, 422–423
cumulative, 418, 419
description of, 405–407
empirical models for predicting rates of, 418–420
flux controlled process of, 407–408
and frozen solids, 631–632
and gravelly soil, 614–615
horizontal versus vertical, 415–417
instantaneous rate of, 407–408
into layered soil, 420, 422
management of, 429, 431–434
measurement of, 428–429
from precipitation, 424–425
profile-controlled process of, 408
relation between surface flux and time during, 424
unsteady, 425–426
for water-repellent soil, 653–654
Water management, 137
Water manometer, 327
Water molecules
description of, 256–257
electric field of, 257
hydrogen bonding of, 257, 258
surface tension of, 258–259
Water movement. See Water flow
Water properties
at atmospheric pressure, 285
boiling point, 268–269
capillarity, 261–264
contact angle, 259–261
fluidity, 267–268
Newtonian and non-Newtonian fluids, 266–267
osmotic pressure, 264
relevant to soil physical properties and processes, 257
Index 681
solubility of, 265
surface tension, 258–289
vapor pressure, 268–269
viscosity, 266–266
water molecule, 256–258
Water repellency, 651–656
classes, 653
effect of wildfire on, 655
effects on soil processes, 653–655
management of, 656
Water retention
in gravelly soils, 610–611
indices for measuring, 129
Water-stable aggregates, 101
Water stage recorder, 276, 277, 430
Water surfaces, albedo for, 524
Water table, management of, 589–590
Water tortuosity (ξ
θ
), 368
Water transmission, 129
Water vapor (H
2
O), 557
Wet bulk density (ρ′
b
), 25
Wetting, in water-repellent soils, 652–653
Wetting front
defined, 408
on layered soil profiles, 420, 422
movement of vapor ahead of, 411
schematic of depth of, 410
schematic of movement through soils, 410
water movement at, 407–412
Wien’s law, 532
Wier, 277
Wildfires, 655–656
Work-energy principle, 322
Worm holes, 221, 222–223
Yield stress model, 190
Young’s equation, 260
Young’s modulus, 194
Zakhrov system of classification of soil structure, 122
Zeta potential, 61–63
effect of increasing, 64–65
effect of lowering, 64, 65
Index 682