Chapter XVIII

PHYSICO-CHEMICAL INVESTIGATION OF SOILS IN RELATION TO CROP
PRODUCTION, 313.—_Historical Review of Soil Investigation_,
313.—Popular Forecasts of Soil Values, 313.—Cogency of
Conclusions Based upon Native Growth, 314.—Ecological
Studies, 315.—Early Soil Surveys of Kentucky, Arkansas
and Mississippi, 316.—Investigation of Cultivated Soils,
316.—Change of Views, 317.—Advantages for Soil Study
offered by Virgin Lands, 318.—Practical Utility of Soil
Analysis; Permanent Value _vs._ Immediate Productiveness,
319.—_Physical and Chemical Conditions of Plant Growth_,
319.—Condition of Plant-food Ingredients, in the Soil,
319.—Water-soluble, Reserve, and Insoluble Part,
320.—Hydrous or “Zeolitic” Silicates, 321.—Recognition of
the Prominent Chemical Character of Soils, 322.—Acidity,
Neutrality and Alkalinity, 322.—Chemical Analysis,
323.—Water-Soluble and Acid-Soluble Portions most
Important, 324.—We cannot Imitate Plant-root Action, 324
Cultural Experience the Final Test, 324.—Analysis of
Cultivated Soils, 325.—Methods of Analysis, 325.—_The
Solvent Action of Water upon Soils_, 327.—Extraction of
Soils with Pure Water, 327.—Continuous Solubility of
Soil Ingredients. Tables, 328.—King’s Results. Table,
329.—Composition and Analysis of Janesville Loam,
331.—Solubility of Soil Phosphates in Water, 332.—Practical
Conclusions from Water Extraction, 332.—_Ascertainment
of the Immediate Plant-food Requirements of Cultivated
Soils by Physiological Tests_, 333.—Plot Tests; their
uncertainties. Diagram, 334.—Crop Analysis as a Test
of Soil Character, 337.—Chemical Tests of immediately
Available Plant Food; Dyer’s Method, 338.