Chapter XII

SURFACE, HYDROSTATIC AND GROUND WATER. PERCOLATION,
215.—Amount of Rainfall, 215.—Natural Disposition of Rain
Water, 216.—The Surface Runoff, 216.—Washing-away and
Gullying in the Cotton States, 217.—Injury in the Arid
Regions, 219.—Deforestation, 219.—Prevention of Injury to
Cultivated Lands from Excessive Runoff, 220.— _Absorption
and Movements of Water in Soils_, 221.—Determination of
Rate of Percolation. Diagram, 221.—Summary, 224.—Influence
of Variety of Grain-sizes, 224.—Table of King’s
Experiments, 224.—Percolation in Natural Soils. Figure,
225.—Ground or Bottom Water, 227.—Lysimeters, Surface of
Ground Water; Variations, 227.—Depth of Ground Water most
Favorable to Crops, 228.—Moisture Supplied by Tap Roots,
229.—Reserve of Capillary Water, 229.—Injurious Rise of
Bottom Water from Irrigation, 230.—Consequences of the
Swamping of Irrigated Lands; Prevention, 231.—Permanent
Injury to certain Lands, 231.—Reduction of Sulfates,
232.—Ferruginous or Red Lands, 233.