INDEX 
critical element, 292; apparent 
increase under dry-farming, 283; 
accumulation in upper layers, 
287; stubble and, 228; reasons 
for dry-farm fertility, 286-292; 
effect of continuous cropping, 
282; maintaining soil fertility, 
281-300; possible equilibrium of, 
293; coming great question, 300; 
and amount to sow, 222; and 
transpiration, 183-186; effect on 
transpiration, 182, 191; evapora- 
tion decreases with, 138; prob- 
lem in California, 383; problem 
in Great Basin, 387. 
Soil-water, see also Water, Capillary 
Water; for loss of, see also Trans- 
piration; in virgin soils, 112; 
why desert soils contain moisture, 
148; how rain-water is changed 
into, 108-110; total water capac- 
ity, 104; hygroscopic moisture, 
102, 137; capillary, 106; field 
capacity for capillary, 107; grav- 
itational, 104; downward move- 
ment, 111-115; dependent on 
pore-space, 102; sinks deeper 
with cultivation, 116; possible 
amount stored in soils, 119; 
storage by fallowing, 122-125; 
thickness of film in per cents, 108; 
effect of thinning the film, 147; 
at harvesting, 117; danger of 
dry soil, 117; importance of 
moist subsoil, 116; demonstra- 
tion that it may mature crops, 
95; necessary to mature crops, 
118; stored in Great Plains soils, 
122; amount stored in Utah 
experiments, 121; methods of 
loss, 165; manner of upward 
movement, 152; how it reaches 
surface, 141; causes of evapora- 
tion of, 160; conditions of evap- 
oration from, 136; evaporation 
proportioned to, 138; dissipated 
by winds, 135; evaporation of 
441 
capillary, 187; effect of rapid 
top drying of soils, 147-152; 
makes independent of rain distri- 
bution, 180; in spring and mid- 
summer, 143; effect on absorp- 
tion, 168; movement through 
plants, 170; effect on transpira- 
tion, 180; and amount to sow, 
222; germination and, insuffi- 
cient, 218; effect on germination, 
209. 
Soils, dry-farm, 50-80; importance 
in dry-farming, 50; formation of, 
physical agencies, 52; chemical 
agencies, 54; physical constit- 
uents of, 56; sizes of particles, 
99; composition of humid and 
arid, 67, 68; characteristics of 
arid soils, 56, 71; definition and 
characteristics of topsoil, 59; 
characteristic structure of arid, 
61; structure of, 99-101; humus 
in arid, 58; depth of, in arid 
countries, 61; depth of dry- 
farming, 62, 78; favorable for 
dry-farming, 77; pore-space of, 
101; alkali, 66; blowing of soils 
in Great Plains, 198; breaking 
soil crust in spring, 227; arid 
soil deficient in clay, 58; native 
vegetation of arid, 79; effect of 
kind, on transpiration, 187, 188; 
for dry-farm, 413; deep soil 
needed, 140; weak and strong, 
58; physical classification of, 
57; judging of, 78; divisions of 
the United States, 74; depth in 
soil-water studies, 119; field 
eapacity for water, 107-110; 
danger of cracks, 141; danger of 
low soil-water, 117; dry surface 
soil to prevent evaporation, 150; 
effect of rapid top drying, 147- 
152; natural mulch on different, 
149; calcareous soils form good 
mulch, 157; civilization and arid, 
73. 
