Chapter X

SOIL AND SUBSOIL IN THEIR RELATIONS TO VEGETATION,
161.—Physical Effects of the Percolation of Surface
Waters, 161.—Chemical Effects; Calcareous Subsoils and
Hardpans, 161.—“Rawness” of Subsoils in Humid Climates,
162.—Subsoils in the Arid Region, 163.—Deep Plowing and
Subsoiling in the Arid Region; examples of Plant growth on
Subsoils, 164.—Resistance to Drought, 167.—Root System in
the Humid Region, 168.—Figures of the Root System of an
Eastern (Wisconsin) Fruit Tree, 168.—_Comparison of Root
Development in the Arid and Humid Regions_, 169.—Prune
on Peach Root, 169.—Adaptation of Humid Species to Arid
Conditions, 169.—Grapes, 170.—Kentucky and California
Maize, 175, 176.—Hops, 172.—Deep-Rooting in the Arid
Region, 174.—Goose Foot and Figwort, 174.—_Importance
of Proper Substrata in the Arid Region_, 173.—Injury
from Impervious Substrata. Figure, 177.—Faulty Lands of
California. Figure, 178.—Shattering of Dense Substrata
by Dynamite, 181.—Leachy Substrata, 182.—“Going-back”
of Orchards, 182.—Hardpan, Formation and Varieties,
183.—Nature of the Hardpan Cements, 184.—Bog Ore,
Moorbedpan and Ortstein; Calcareous and Alkali Hardpan,
184.—The Causes of Hardpan, 185.—“Plowsole,” 186.—Marly
Substrata, 186.