Chapter XIII

WATER OF SOILS; THE REGULATION AND CONSERVATION OF SOIL,
MOISTURE; IRRIGATION, 234.—Loosening of the Surface,
234.—Effects of Underdrains; Rain on Clay Soils,
235.—Winter Irrigation, 236.—_Methods of Irrigation_,
236.—Surface Sprinkling, 237.—Flooding, 237.—Check
Flooding. Furrow Irrigation, 237, 238.—Figure Showing
Penetration, 239.—Figure Showing Faulty Irrigation
in Sandy Lands, 239.—Distance between Furrows and
Ditches, 241.—Irrigation by Lateral Seepage, 242.—Basin
Irrigation of Trees and Vines; Advantages and Objections,
243.—Irrigation from Underground Pipes, 245.—_Quality of
Irrigation Waters_, 246.—Saline Waters; Figures of Effects
on Orange Trees, 246.—Limits of Salinity, 246.—Mode of
Using Saline Irrigation Waters; Apparent Paradox, 249.—Use
of Drainage Waters for Irrigation, 250.—“Black Alkali”
Waters, 250.—Variations in the Salinity of Deep and Shallow
Wells, 250.—Muddy Waters, 251.—_The Duty of Irrigation
Waters_, 251.—Causes of Losses, 252.—Loss by Percolation.
Figure, 252.—_Evaporation_, 253.—Tables Showing same
at California Stations, 255.—Evaporation in Different
Climates; Table, 255.—Evaporation from Reservoirs and
Ditches, 257.—Prevention of Evaporation; Protective Surface
Layer, 257.—Illustrations of Effects of Tillage; Table,
258.—Evaporation through Roots and Leaves, 262.—Weeds
waste Moisture, 264.—Distribution of Moisture in Soils
as Affected by Vegetation, 264.—Forests and Steppes,
265.—Eucalyptus for Drying Wet Lands, 265.—Mulching;
Effects on Temperature and Moisture, 266.