INDEX 
Clay, from combined silica; in 
soils, 56; and climate, 57; and 
hardpan, 64; and native vege- 
tation, 80; soils defined, 57; in 
soil classification, 57; depth of 
planting in, 221; soils respond 
to cultivation, 157. 
Clearing, machinery for clearing 
land, 302. 
Climate, climate features of dry-farm 
area, 35; summary of climate in 
dry-farm territory, 48; does not 
change, 400; and proportion of 
plant parts, 261. 
Clover, pounds water for one pound, 
15; taproot of, 83; for nitrogen, 
297. 
Coal, for steam pumps, 342. 
Colorado, area, 26; type of rainfall 
over, 40; soils of, 74, 76; nitrogen 
in Colorado soils, 286; deep and 
fall plowing in, 195; fallowing 
in, 197; field peas in, 249; milo 
in, 246; dry-farm orchard in, 
252; pumping plants in, 342; 
first Dry-Farming Congress held 
in Denver, 374; present status 
of dry-farming in, 389. 
Colorado Basin, soil district, 76; 
status of dry-farming in, 388. 
Colorado, Cafton of, description, 35. 
Colorado Station, first experiments 
on dry-farming, 366. 
Columbia Basin, description, 36; 
soil districts, 74; use of roller in, 
815; weeder used in, 314; be- 
ginnings of dry-farming in, 357; 
an originator of dry-farming, 
193; present status of dry-farm- 
ing in, 384. 
Commercial fertilizers, 
farming, 296. 
Composition, chemical composition 
of arid and humid soils, 68; of 
crops, 257-277; young plants 
rich in protein, 274; commer- 
cial value of superior quality of 
and dry- 
431 
dry-farm crops, 278; variations 
due to climate, 271-274; varies 
with water supply, 267-271; a 
reason for variation in, 274-275; 
causes of variations in, 267. 
Continuous cropping, dangerous, 
203. 
Cooke, 369. 
Corn, 243; pounds water for one 
pound, 15, 16; depth of root 
penetration, 86, 87; root sys- 
tem, 83; water absorbed by 
seeds of, 209; repeated drying 
in germination, 218; amount to 
sow, 224; mechanical planters, 
320; harvesters for, 321; varia- 
tion in composition, 267; im- 
portance of humus for, 297; 
water and yield, 346. 
Cracked land, danger of, 141. 
Crimean wheat, 238. 
Crop, see also Plant; for dry-farm- 
ing, 232; for irrigation and dry- 
farming, 256; varieties, 234; 
condition of good dry-farm, 234; 
adaptation of, 232; care of, 226; 
harrowing of, 162; not on fallow 
land, 124; composition of dry- 
farm, 257; nutritive substances 
in, 264; from dry-farms highly 
nutritious, 275; water in dry- 
farm, 262; yield varies with 
water applied, 345; producing 
power of rainfall, 18;  soil- 
water necessary to mature, 118; 
effect on transpiration, 178; to 
prevent soil blowing, 198; special- 
izing in dry-farm, 279; problems, 
256. 
Cultivation, see also, Tillage; saves 
moisture, 152-156; experiments: 
showing value of cultivation in 
reducing evaporation, 154-155; 
increases depth of soil-water, 116; 
effect on transpiration, 187; and 
humus, 198; and root systems, 
92; time of, 158; after rains, 
