Soils, their formation, properties, composition, and relations to climate and plant growth in the humid and arid regions

by Eugene W. Hilgard

CHAPTER XIV.

Absorption by Soils of Solids from Solutions. Absorption of Gases, Air of Soils, [267].—Absorption of Solids, [267].—Desalination, [267].—Decolorization, [267].—Complexity of Soil-Action, Physical and Chemical, [268].—“Purifying” Action of Soils on Gases and Liquids, [269].—Waste of Fertilizers, [269].—Variation of Absorptive Power, [270].—Generalities Regarding Chemical Action and Exchange, [270].—Drain Waters, [271].—Distinctions not Absolute, [272].—Absorption or Condensation of Gases by the Soil, [272].—Proof of Presence of Carbonic and Ammonia Gases in Soils, [273].—Absorption of Gases by Dry Soils. Figure, [274].—Composition of Gases Absorbed by Various Bodies from the Air. Table, [275].—Discussion of Table, [277].—The Air of Soils, [279].—Empty Space in Dry Soils, [279].—Functions of Air in Soils, [279].—Insufficient and Excessive Aeration, [280].—Composition of the Free Air of Soils, [280].—Carbonic Dioxid vs. Oxygen, [281].—Relation to Bacterial and Fungous Activity, [281].—Putrefactive Processes, [282].

CHAPTER XV.

Colors of Soils, [283].—Black Soils, [283].—“Red” Soils, [284].—Origin of Red Tints, [285].—White Soils, [285].—Differences in Arid and Humid Regions, [286].—White Alkali Spots, [286].

CHAPTER XVI.

Climate, [287].—Heat and Moisture Control Climates, [287].—Climatic Conditions, [287].—Ascertainment and Presentation of Temperature Conditions, [288].—Annual Mean not a Good Criterion, [289].—Extremes of Temperature are most Important, [289].—Seasonal and Monthly Means, [289].—Daily Variations, [290].—The Rainfall, [290].—Annual Rainfall not a Good Criterion, [290].—Distribution most Important, [290].—Winds, [291].—Heat the Cause of Winds, [291].—Trade Winds, [291].—Cyclones, [292].— Influence of the Topography on Winds; Rains to Windward of Mountains, Arid Climates to Leeward, [293].—General Distribution of Rainfall on the Globe. Figure, [294].—Ocean Currents, [295].—The Gulf Stream, [295].—The Japan Stream, [296].—Contrast of Climates of N. W. America, [297].—Continental, Coast and Insular Climates, [297].—Subtropic. Arid Belts, [298].—Utilization of the Arid Belts, [299].

CHAPTER XVII.

Relations of Soils and Plant Growth to Heat, [301].—Temperature of Soils, [301].—Water Exerts Controlling Influence, [301].—Cold and Warm Rains, [302].—Solar Radiation, [302].—Penetration of the Sun’s Heat into the Soil, [302].—Change of Temperature with Depth, [303].—Surface Conditions that Influence Soil Temperature, [303].—Heat of High and Low Intensity, [304].—Reflection vs. Dispersion of Heat, [304].—Influence of Vegetation, and of Mulches, [305].—Influence of the Nature of the Soil-Material, [306].—Influence of Evaporation, [307].—Formation of Dew, [307].—Dew rarely adds Moisture, [308].—Dew within the Soil, [308].—Plant Development under Different Temperature-Conditions, [309].—Germination of Seeds; Optimum Temperature for each Kind, [309].—Artificial Heating of Soils; by Steam Pipes or Water, [310].

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].