INDEX 439 
Precipitation, see Rainfall. 
Problems, of dry-farming, 6. 
Protein, in plants, 266; acquired 
early by plants, 274; function 
of, 264; more protein in dry-farm 
crops, 269. 
Puddling, to be avoided, 159. 
Pumping, area irrigated from pump- 
ing, 341; crop possibilities of 
small plant in Arizona, 348; 
water for dry-farms, 341; by 
windmills, 341; cost of, in Ari- 
zona, 344; cost of pumping in 
California, 344; cost of pumping 
in Kansas, 344; cost of, in New 
Mexico, 343. 
Quality, valuation of dry-farm 
crops, 257; on basis of water 
content, 263. 
Rabbit-brush, 80. 
Railroads, and dry-farming, 363, 
370. 
Rainfall, see also Natural Precipita- 
tion, Winter Precipitation; rec- 
ords insufficient in dry-farm 
territory, 28; distribution over 
earth-surface, 33; types of 
distribution, 38-40; distribution 
less important, 130; in spring or 
summer causes loss of soil-water, 
130, 160; average does not 
change, 400; chief factor in de- 
termining aridity, 25; over one 
acre in pounds, 19; and native 
vegetation, 79; how disposed of, 
97; depth of penetration, 114; 
downward movement in soil, 60; 
amount stored in soils, 114-115; 
effect of small rains on soil- 
moisture, 113; importance of 
moist subsoil in storm, 116; 
proportion stored in Great Plains 
soils, 122; amount stored in Utah 
soils, 121; and plant growth, 
261; crop-producing power of, 
18, 20; limits for dry-farming, 
1, 22; dry-farming with less 
than 10 inches, 357, 385; and 
amount to sow, 222; and fall 
sowing, 216; irrigation supple- 
mentary only to, 345; stored in 
cisterns, 336. 
Reclamation Service, United States, 
on area of desert land, 29. 
Record, continuous record of Barnes 
farm, 403; continuous record of 
Indian Head Station, 406. 
Red chaff wheat, 240. 
Red clover, pounds water for one 
pound, 14. 
Red Fife wheat, 237. 
Red Russian wheat, 240. 
Relative Humidity, defined, 135; 
over dry-farm territory, 46; 
effects of, in New York and Salt 
Lake City, 135; influence upon 
transpiration, 176. 
Reservoirs, for flood water, 334; 
building, 337. 
Rio Grande Basin, status of dry- 
farming in, 388. 
Rocks, crystalline rocks and clay 
soils, 57. 
Rocky Mountains, description of the, 
35. 
Roller, use of, on crop, 226, 227, 
315. 
Root-hairs, organs of absorption, 
167; immersion in soil-water, 
168. 
Roots, functions of, 81; kinds of, 
82; taproot, 83; fibrous, 83; 
systems, 81; extent of, 84; 
weight of, 84, 85; depth of pene- 
tration, 86; direction of develop- 
ment, 89; development under 
arid conditions, 88; develop- 
ment under irrigation, 90; sys- 
tems in arid vs. humid climates, 
92; conditions of deep rooting, 
93; deep root systems and fer- 
tility, 287, 292; and deep culti- 
