CHAPTER X.. Soil and Subsoil in Their Relations to Vegetation,

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.