CHAPTER XXII.

ALKALI SOILS, THEIR NATURE AND COMPOSITION, 422.—Alkali Lands _vs._ Seashore Lands, 422.—Origin, 422.—Deficient Rainfall, 423.—Predominant Salts, 423.—Geographical Distribution, 424.—Their Utilization of World-wide Importance, 424.—Repellent Aspect, Plate, 424.—Effects of Alkali upon Culture Plants. Figures of Apricot Trees, 426.—Nature of the Injury, External and Internal, 426.—Effects of Irrigation, 428.—Leaky Irrigation Ditches, 429.—Surface and Substrata of Alkali Lands, 429.—Vertical Distribution of the Salts in Alkali Soils, 429.—How Native Plants Live, 430.—Figures of various Phases of Reclamation, 431.—Upward Translocation from Irrigation, 433.—Distribution of Alkali in Sandy Lands, 433.—In Heavier Lands, 436.—Salton Basin or Colorado Delta, 436.—Diagram of Alkali Distribution in Same, 438.—Horizontal Distribution of Alkali Salts in Arid Lands, 439.—Alkali in Hill Lands, 439.—Usar Lands of India, 440.—“Szek” Lands of Hungary, 440.—Alkali Lands of Turkestan, 441.—_Composition and Quantity of Salts Present_, 441.—Nutritive Salts, 441.—Black and White Alkali. Tables, 442.—Estimation of Total Alkali in Land, 444.—_Composition of Alkali Soils as a whole._ Tables, 445.—Presence of much Carbonate of Soda, 448.—Cross Section of an Alkali Spot. Table, 448.—_Reactions between the Carbonates and Sulfates of Earths and Alkalies._ Figure of Curve, 449.—Inverse Ratios of Alkali Sulfates and Carbonates. Diagrams, 451.—Exceptional Conditions, 453.—Summary of Conclusions, 453.