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 Syllabus of first course in soils ... 
 
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SYLLABUS 
 
 OF 
 
 FIRST COURSE IN SOILS 
 
 CORNELL UNIVERSITY 
 
 Prepared By ' 
 
 ELMER O. PIPPIN 
 
 December 1905 
 (Rights Reserved) 
 
I Cornell University 
 y Library 
 
 The original of tiiis bool< is in 
 tine Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31924000298780 
 
I. THE LAND AREA OF THE UNITED STATES. Parts 
 economic. 
 
 A. Non-agricultural. 
 
 I. Location; 2. Extent; 3. Surface features; 4- General 
 
 Characteristics. 
 
 B. Agricultural. 
 
 I. Location; 2. Area; 3- Farm Area; 4. Per cent 
 
 improved. 
 
 C. Divisions of Country according to temperature. 
 
 a. Northern. Cool. 
 
 b.. Southern. Warm temperature and sub-tropical. 
 
 D. Divisions of Country by rainfall. 
 
 a. Humid. 
 
 I. Location; 2. Area; 3. General Character. 
 
 b. Sub-Humid. 
 
 I. Location; 2. Extent; 3. Character. 
 
 c. Arid. 
 
 I. Location; 2. Extent; 3. Character. 
 
 IL CROPS PRODUCED IN THE UNITED STATES. 
 
 A. Staple. 
 
 a. I. Corn; 2. Wheat; 3. Cotton; 4. Hay; 5. Oats. 
 
 b. I. Total yields ; 2. Average acre yields ; 3. Maximum 
 recorded acre yields. 
 
 B. Special Crops. 
 
 a. Tree fruits. 
 
 b. Small fruits. 
 
 c. Truck Crops. 
 
 d. Tobacco, etc. 
 
 III. DETERMINING FACTORS IN CROP YIELDS ARE 
 THE KNOWN ESSENTIAL FACTORS OF PLANT 
 GROWTH. 
 
 A. Seed. Vitality and hereditary powers. 
 
 (Province of crop study proper.) 
 
B. Food. 
 
 C. Moisture. 
 
 D. Light and heat. 
 
 E. Air (oxygen) 
 
 F. Mechanical support. 
 
 Setting aside the Hfe factor involved in the seed the produc- 
 tion of the maximum plant development depends on the supply of 
 the last five factors. Heat and light are such closely related physical 
 phenomena, they may be considered together. All of these factors 
 may be controlled within limits. They come within the province of 
 the Study of Soils and each may be discussed with reference to the 
 following outline : i". Source ; 2. Characteristics ; 3. Amounts ; 4. 
 Occurrence ; 5. Relationships ; 6. Means of Modification. 
 
 The Soil Defined. It is the unconsolidated but slightly coher- 
 ing mass of rock fragments and secondary chemical products derived 
 therefrom, mixed with varying amounts of organic remains ; contains 
 some water and air, and usually minute forms of plant life ; has a 
 considerable degree of heat, forms the surface of the earth and in 
 which plants will ordinarily grow. 
 
 IV. FOOD. 
 
 A. Requirements of plants, 
 a. Composition of plants. 
 
 1. Volatile. 
 
 (a). Water. Proportion in a number of common 
 
 plants, 
 (b). Organic material. Element and proportions 
 
 N. H. O. C. 
 
 2. Non-volatile. Mineral elements. 
 
 (a). Ash. Amounts in a number of common plants 
 
 and parts of plants, 
 (b). Component elements, 
 (c). Essential elements. 
 
 K. Ca. Fe. S. Mg. P.— Doubtful. Na. Al. Si. CI. 
 b. Source of essential elements. 
 I. Volatile. 
 
 (a). Air. Carbon and Oxygen. 
 
(b). Water. Oxygen and Hydrogen, 
 (c). Soil. Nitrogen. 
 2. Non-volatile. Mineral elements^ 
 (a). All derived from the soil. 
 B. The soil as a source of food. Phases. • 
 
 a. Solid. 
 
 b. Liquid. 
 
 c. Gaseous. 
 
 a. THE SOLID PHASE OF THE SOIL. Derivation. 
 
 I. Inorganic. Rock fragments and secondary chemical 
 compounds derived from rock. 
 Definition of a Rock. (Merrill). A rock is a mineral aggre- 
 gate which is an essential portion^ of the earth's crust and occupies 
 a more or less well defined position in the structure of the earth. 
 
 Definition of a Mineral. A mineral is a compound occurring 
 in nature having theoretically a definite chemical composition and 
 crystalline form and usually definite physical properties'. 
 X. Source of soil material. 
 
 (a). List of most common soil forming minerals and 
 chemical composition of each, 
 (i) Quartz; (2) Feldspar; (3) Amphiboles ; (4) 
 Pyroximes; (5) Micas; (6) Calcite; (7) Halite; (8) 
 Pyrite, and the secondary minerals; (9) Glanconite; 
 (10) Kaolin and (11) the Zeolites, 
 (b). The eight most abundant elements in the earth's 
 crust and their, proportion. 
 Oxygen, 47.0 per cent. 
 
 Silicon, 27.9 
 
 Aluminum, 8.1 
 
 Iron, 4.7 
 
 Calcium, 3.5 
 
 Magnesium, 2.5 
 
 Potassium, 2.4 
 
 Sodium, 2.7 
 
 98.8 " " 
 (c). Classification of the common soil forming rocks, 
 (i) Igneous. 
 Crystalline and non crystalline. 
 
Acid, intermediate, basic. 
 
 (2) Aqueous: 
 
 (A). Chemical precipitates. 
 Oxides, chlorides, carbonates, silicates, sulphates, 
 phosphates, hydrocarbons. 
 (B). Sedimentary deposits. 
 Inorganic materials. 
 
 Arenaceous, (Sandy, frravell>.) 
 
 Argillaceous. (Clayey.) 
 
 Calcarious. 
 
 Volcanic dust. ^ 
 
 Organic materials, organaceous. 
 
 Silicious. 
 
 Calcarious. 
 
 Carbonaceous. 
 
 Phosphatic. 
 
 (3) Aeoleon. 
 
 Volcanic dust, Dune sand. Loess ( ?) Adobe ( ?). 
 
 (4) Metamorphic. 
 Agencies of metamorphism. 
 
 (a). Stratified materials, slate, marble. 
 (b). Folialed materials, Gneisses, Schists, 
 (d). The similarity in chemical composition as regards 
 the elements present, of rocks of widely different 
 origin and character. 
 Destruction of rocks to form soils. 
 Agencies, 
 (a). Chemical, 
 (i) Atmosphere 
 Oxygen. 
 Carbon dioxide. 
 
 Nitrogen, nitric acid and ammonia. 
 (2) Water. 
 Oxidation. 
 De-oxidation. 
 Hydration. 
 Solution. 
 Decomposition. 
 Weathering defined. 
 
(b). Mechanical. 
 
 (i) Changes of temperature. 
 
 Unequal expansion and contraction. 
 
 (2) Action of water. 
 Flowing, as streams. 
 Waves. 
 
 Frozen. Expansion of freezing. 
 Frost and the porosity of rocks. 
 Glaciers. 
 
 (3) Plants- and animals. 
 
 Growth of roots, burrowing of animals and insects 
 and the chemical action of organic remains. 
 Disintegration. 
 Z. Classification of Soils, Basis ; Extent of transportation 
 and process of derivation, 
 (a). Sedentary, Definition. 
 
 ( I ) . Residual Soils, Conditions influencing their char- 
 acter. 
 (a). Composition and texture of parent rock. 
 (b). Position, 
 (c). Atrnospheric conditions. 
 
 Humidity and temperature. 
 Amount of material removed and relation of com- 
 position of derived material to original rocks. 
 Examples. 
 
 Percentage loss of each constituent. 
 Comparison of rocks with the residual soils derived 
 from them. Granite, Gneiss, Dibose, Diorite, Soap- 
 stone, Argillite, Limestone, Sandstone. 
 (2) Cumulose soils; Organic remains. Muck, Marsh 
 and Swamp. 
 
 (More complete under organic matter.) 
 (b). Transported. Definition. 
 
 ( 1) By gravity. Colluvial. Talus. Cliflf, debris, ava- 
 lanche material, etc. 
 
 (2) By Water. 
 
 As liquid. Relation of size of particles carried varies 
 as sixth power of velocity of flow and square of 
 diameter of particles. Sorting action of. 
 
(a). Modern alluvium. Composition and uniform 
 ity of materials. Characteristics' of such depos 
 its. Stream deltas. 
 (b). Lake and ocean deposits. Character of strat- 
 ification. Shore deposits. Surface features. 
 As Solid. 
 
 (a). Floating ice. 
 
 (b). Glacial ice. General conditions. 
 Character of erosion. 
 Peculiarities of material. 
 General. 
 
 Texture fine but variable and indefinite. 
 No stratification. 
 Material sharply angular. 
 Section compact. 
 Proportion of silt to clay large. 
 In general in United States more productive 
 residual soils. 
 (3) Aeolean Soils, Wind Carried. 
 Sand dines. 
 Volcanic dust. 
 Loess and Adobe (?). 
 (c). Resume of location, extent, general character 
 and crop interests of the soil provinces of the 
 United States. 
 (i) Residual. 
 
 (a). From igneous rocks. • 
 
 (b). From aqueous rocks. . : j 
 
 (2) Cumulose. ■•■ 
 
 (3) Cullovial. 
 
 (4) Alluvial. 
 
 (5) Sedimentary proper. 
 
 (6) Glacial Division. 
 (a). New England. 
 
 (b). New York, N. Y., Penn. and Ohio, 
 (c). Central. (Ohio, Ind., 111., Mich., Wis.) 
 (d). Western. (Glacialed area west of Mis- 
 sissippi and east of Rocky Mts.) 
 
 (7) Aeolean. 
 
2. Organic matter in the soil. As a source of plant food and 
 
 as a physical factor. 
 X. Sources. 
 
 (a). Plants. Arborescent, fungicidal, bacteria, 
 (i) Decay in the soil. 
 Conditions favoring. 
 Processes. 
 Products. Humus. Acids and gases. 
 (2) Amounts and composition of humous in the 
 important soil areas of the United States. 
 Northern and Southern States. 
 Eastern and Western States. 
 Humid and arid States, 
 (b). Animals. 
 
 (i) Earth worms, insects and burrowing animals. 
 Extent and importance of their work. 
 Y. Effects of organic matter on the soil, 
 (a). Physical. 
 
 (i) Color and heat. 
 
 (2) Tilth and granulation. 
 
 (3) Water holding capacity, 
 (b). Chemical. 
 
 ( 1 ) Solvent agent-carbon-dioride and higher acids. 
 
 (2) As plant food. 
 
 a. SOLID PHASE OF THE SOIL. Physical properties. 
 I. Texture. Definition. 
 X. Size and shape of particles. 
 
 (a). System of grouping particles by size. 
 
 (i) Stone ( 
 
 3ver 10. m. m. diarr 
 
 (2) Coarse gravel 
 
 5- -10. 
 
 
 
 (3) Medium gravel 
 
 2- - 5- 
 
 
 
 (4) Fine gravel 
 
 I. - 2. 
 
 
 
 (5) Coarse sand 
 
 0.5 - I.O 
 
 
 
 (6) Medium sand 
 
 0.25 - 0.5 
 
 
 
 (7) Fine sand 
 
 o.io - 0.25 ' 
 
 
 
 (8) Very fine sand 
 
 0.05 - 0.10 ' 
 
 
 
 (9) Silt 
 
 o.oi - 0.05 ' 
 
 
 
 (10) Fine silt 
 
 0.005- O.OI ' 
 
 
 
 (11) Clay 
 
 0.000- 0.005 ' 
 
 
 
y). Number of particles and surface area per grain- 
 
 of pure separates, 
 (z). Natural classification of soils on basis of texture 
 into sands, sandy loams, loams, clays, etc., 
 
 ( 1 ) Illustrated by curves for natural soils. 
 
 (2) Number of particles and surface area per 
 pound of number of typical soils such as truck,, 
 tobacco, corn, wheat and grass soils. 
 
 Structure. Definition. 
 X. Physical effects of structure on 
 
 (a). Granulation and tilth. 
 
 (b). Porosity. 
 
 ( 1 ) Natural porosity as effected by size of parti- 
 cles. 
 
 (2) As modified by structure. 
 Character of packing. 
 
 (3) Porosity of some field soils, 
 (c). Specific Gravity. 
 
 (i) Absolute. Average— 2.65. Modified by- 
 character of niaterial. 
 Variation in pure separates. 
 (2) Apparent, for a number of common field" 
 soils. 
 1.2 — 1.6. 
 (d). Some prominent examples of soil structure, 
 (i) Sod and cultivated land. 
 (2) Puddled and granular soil. 
 Susquehanna Clay. 
 Hagerstown Clay. 
 '. Origin of structure and means of modification, 
 (a). Variation of water content. 
 Alternate wetting and drying. 
 
 ( 1 ) Friction reduced. Puddling and plasticity. 
 
 (2) Contraction of water films. 
 
 Force of in small weight of soil. Relation to- 
 
 Clod formation, 
 (b). Variations of temperature. 
 
 Including freezing, of soil moisture. 
 (c). Effect of organic matter on 
 
(i) Temperature. 
 
 (2) Moisture. 
 
 (3) Porosity. 
 
 (d). Cultural processes. 
 
 (i) Plowing. Principles of. 
 
 Shearing nature of, types of moldboard, depth. 
 Moisture condition of soil. 
 
 (2) Rolling. Decreases pore space. 
 
 (3) Cultivation. General. 
 
 (4) Effect of these on moisture and heat, 
 (e). Development of plant roots. 
 
 (f). Action of chemical. Flocculation and de-floc- 
 culation of. 
 z. Erosion and the control of. 
 (a). By water. Controlled by. 
 (i) Deep plowing. 
 
 (2) Favoring granulation. 
 
 (3) Addition of organic matter. 
 
 (4) Protective covering. 
 
 (5) Underdrainage. 
 
 (6) Contour forming. 
 
 (7) Side hill ditches. 
 
 (8) Terracing. 
 
 (b). By wind. Controlled by 
 (i) Favoring granulation. 
 
 (2) Rough surface and wind brakes. 
 
 (3) Addition of organic matter. 
 
 &. Differences between arid arid humid soils, 
 (a). In proportion of coarse textured material, 
 (b). Small per cent of clay in arid soils, 
 (c). Distinctions between soil and subsoil ver} 
 
 slight., 
 (d). Larger amounts of readily soluble material, 
 (e). Small amounts of organic matter, 
 (f). Particles more angular and fresh. 
 
 PLANT NUTRITION IN ITS RELATION TO THE SOIL. 
 
 a. Structure of Aborescent plants, 
 (i) Stem and branches. 
 (2) Roots. 
 
lO 
 
 (3) Leaves, 
 b. Some principles of nutrition. 
 
 (i) Elements and their source. Solution. 
 
 (2) Movements of, in the plant, 
 (a). Osmatic. 
 
 (b). Capillary, 
 (c). Diffusion, 
 (d). Vital function. 
 
 (3) Movement of food constituents to the roots in 
 solution. 
 
 (4) Root systehis of plants as foragers. Types — (a). 
 Tap, (b). Fibrous. 
 
 Depth and width of extension, 
 (a). Corn, 
 (b). Wheat, 
 (c). Oats, 
 (d). Grasses, 
 (e). Legumes. 
 
 (f). Root and tuberous crops. 
 (5). Development of roots as affected by soil texture 
 and structure, 
 (a). Influence of cultured methods, 
 (b). Drainage and irrigation. 
 
 b. THE LIQUID PHASE OF THE SOIL. 
 
 I. Water. 
 X. Uses. 
 
 (n). As a food. 
 
 (i) Proportion in plants, 
 (b). As a carrier of plant food from the soHd 
 soil to the plant tissues, 
 (i) Amounts required for production of dry 
 matter in common form crops. 
 250-500 pounds per pound of dry matter. 
 y. Sources, 
 (a). Rain, 
 (b). Snow, 
 (c). Dew. 
 (d). Condensation. 
 z. Amounts in soil. Determined bv 
 
II 
 
 (a). Available supply, 
 (b). Capacity of soil, modified by 
 (i) Texture. 
 
 (2) Structure. 
 
 (3) Organic content, 
 (c). Rate of loss of water. 
 
 Maximum, minimum and optimum water content. 
 Saturation and method of stating water content. 
 Amounts of different forms of water in soils of different 
 texture and structure. 
 &. Movements of water in the soil, 
 (a). Gravitational. Determined by. 
 (i) Texture. 
 (2) Structure. 
 
 Leacking and drainage. (Brief) 
 (b). Capillary movement. 
 
 (i) Principles of capillary movement. 
 
 Due to surface tension. List of, for solu- 
 tions. 
 
 (2) Rate of movement. Determined by 
 Texture and Structure. — Friction. 
 Condition of surfaces. 
 
 (3) Extent and importance. 
 
 (a). Conducting moisture into the soil. 
 (b). Lateral and vertical movement of water. 
 Height water may be raised in soils of 
 different texture, 
 (c). Amounts of water moved by capillary, 
 .ileans of Controlling Water Content of the Soil, 
 (a). Decreasing loss from 
 
 ( 1 ) Leaching. 
 
 (a). By modification of texture. 
 
 Foreign materials, etc. 
 (b). By modification of structure. 
 
 Plowing, cultivation, etc. 
 
 (2) Surface evaporation. 
 
 (a). Mulches. Principle of action. 
 
 (i) Foreign materials, straw, leaves, sawdust, 
 sand, etc. 
 
12 
 
 (2) Dust mulches of natural soil. 
 Effective depth of. 
 Frequency of renewal. 
 (b). Reduction of wind movement. 
 Rough. ' Surface. 
 Wind brakes, 
 (b). Increasing the water content of the soil. Capacity, 
 (i) By modification of texture and structure. 
 (a). Addition of other soil. 
 (b). Cultural operations. 
 
 (2) By increasing the humous content. 
 Forms. 
 
 (a). Organic refuse. Manures. 
 
 Sewage, Street Sweepings, etc. 
 (b). Green manures. Principals governing use of. 
 (i) Selection of crop. 
 Time of plowing. 
 
 Insuring decay. ' ' 
 
 Conservation of moisture and food, etc. 
 
 (3) By deep plowing and subsoiling. 
 (a). Reasons for ' 
 
 (b). Soils so adapted. 
 
 (c). Time. — Fall, Spring — Early, Late. 
 
 (d). Method. Sub-surface packing, etc. 
 
 (4) Irrigation. 
 
 (c). Decreasing the water content of the soil, 
 (i) Drainage. 
 
 (a). Open ditches. 
 (e). Tile ditches, 
 (c). Rate. Determining factors, 
 (i) Slope of surface. 
 
 (2) Texture of soil. 
 
 (3) Structure of soil. 
 (d). Effects of drainage. 
 
 (i) Removes excess water. 
 
 (2) Improves soil structure and tilth. 
 
 (3) Renders soil more firm. 
 
 (4) Increases available water. 
 
 (5) Increases root penetration. 
 
13 
 
 (6) Raises the temperature and lengthens the 
 growing season. 
 (2) Surface Culture. 
 
 (a). Smooth bare surfaces, 
 (b). Ridge culture, 
 (c). Growth of crops. 
 The Soil Solution. 
 
 The relation of its composition to the chemical nature of 
 the solid soil. 
 
 X. The soil solution as the nutrient medium. 
 
 (a). Source of the mineral elements and nitrogen, 
 (b). Compositions and factors controlling same, 
 (i) Composition of the solid portion of the soil. 
 (a). Universality of the essential elements in the 
 
 mineral constituents of the soil. 
 (b). Universal solubility of the minerals. 
 Rate and extent determined by 
 (i) Fineness of division. 
 
 (2) Material already in solution. 
 
 (3) Time element for equilibrium. 
 
 (4) Absorption phenomenon. 
 
 (5) Soil acidity. 
 
 (2) Amount of water present. 
 
 (a). As affecting amount of material in solution. 
 (b). As affecting the concentration of the solu- 
 tion, 
 (i) Alkali and alkali soils. 
 Character and extent. 
 
 (3) Soluble material in some common field soils. 
 
 (4) Manures as a means of modifying the com- 
 position of the soil solution, and as a source 
 of plant food. 
 
 (a). Historical. Extent and period of uses. 
 
 (b). Facts associated with use of. 
 (i) Organic remains. 
 Manures. 
 Green manures. 
 
 Crops improved and extent of improve- 
 ment. 
 
14 
 
 (2) Chemicals, 
 (a). Elements commonly regarded as neces- 
 sary in fertilizers. 
 Potash, Phosphorus, Nitrogen, 
 (b). Elements questionably needed. 
 Calcium, Magnesium, Sodium, 
 (c). The theory of the use of fertilizers. 
 
 Modification of the soil solution as a: 
 direct plant food. 
 Data supporting, 
 (d). Natural supply of most essential ele- 
 ments, 
 (i) Potash and phosphoric acid. 
 Deposits in beds. 
 Deposits as part of rock mosses. 
 (2) Nitrogen. Atmosphere as the supply. 
 
 a. Dependence of plants on nitrates in.< 
 the soil. 
 
 b. Nitrogen fixation. 
 
 (i) Electrical discharges. 
 
 Nitric acid and ammonia in rain. 
 
 water. 
 
 Amounts. 
 
 (2) Processes of natural and artifi- 
 cial combustion set free nitrogen^ 
 compounds. 
 
 (3) Organic accumulations. 
 Guanos. 
 
 Derived salts in form of nitrate. 
 
 (4) Bacterial agencies of fixation of 
 nitrogen. 
 
 Historical. 
 
 Plants with which associated. 
 Legumes. 
 
 c. Species and dependencies. — Parasites.. 
 
 d. Occurrence and distribution. 
 
 e. Conditions of growth. 
 
 Heat, air, (oxygen) moisture. 
 Mineral food. 
 
15 
 
 f. Beneficial effects, 
 (i) How derived. 
 
 (2) Extent to which nitrogen is fixed 
 by nodular forming bacteria. 
 
 (3) Importance in agricultural prac- 
 tices. 
 
 (4) Propagation by 
 Soil transfer. 
 
 Pure cultures. Use of. 
 y. Some physical as well as chemical effects associated 
 with the use of manures, 
 (a). Texture, 
 (b). Structure. 
 
 Flocculation and de-flocculation. 
 (c). Color, from organic matter and other materials, 
 (d). Effect of salts in solution on surface tension and 
 
 hence on extent and rate of capillary movement 
 
 of moisture. 
 
 V. THE SOIL ATMOSPHERE. (OXYGEN). 
 
 1. Importance in plant growth. 
 
 (a). Chemical. In decay processes and oxidation, 
 (b). Vital function of plant roots and bacterial life. 
 
 2. Amounts in the Soil, 
 Determined by. 
 
 (a). Porosity of soil. Size and distribution of spaces. 
 (a). Texture. 
 (b). Structure. 
 
 3. Composition as compared with normal atmosphere, 
 (a). Amounts of carbon dioxide. 
 
 (b). Amounts of nitrates and ammonia, 
 (c). Other complex gaseous products of orgamc 
 decay. 
 
 4. Movements of soil atmosphere. 
 Due to. 
 
 (a). Barometric changes, 
 (b). Surface winds. 
 
i6 
 
 (c). Diffusion, 
 (d). Temperature changes, 
 (e). Movements of water. 
 5. Means available for modifying the atmospheric con- 
 tent of soil, 
 (a). Drainage, 
 (b). Cultivation, 
 (c). Incorporation of foreign material. Textural and 
 
 structural changes. 
 
 (a). Sand. 
 
 (b). Clay. 
 
 (c). Organic material. 
 
 VI. HEAT OF THE SOIL. 
 
 a. Importance in plant growth. 
 Energy and plant food relations. 
 
 b. Source. Solar heat. Interior of earth, organic decay. 
 
 c. Means of transfer to the soil. 
 
 1. Molecular activity. 
 
 2. Atmosphere. 
 
 3. Rain. 
 
 d. Temperature of the soil, 
 Determined by. 
 
 1. Specific gravity. 
 
 2. Specific heat. 
 
 3. Conductivity. 
 
 4. Color. 
 
 (a). Modification of temperature by. 
 
 Extent of on light and dark colored soils, 
 (b). Common soil colors. 
 
 (i) Their source 
 
 (2) Indications, as a key to the condition 
 of. the soil. 
 
 5. Position. — Attitude. 
 
 6. Water content. 
 
 (a). Specific heat of water as compared with rock 
 particles. 
 
17 
 
 (b). "Warm and cold soils." 
 (c). "Late and early soils." 
 Means of modifying the temperature of the soil, by 
 
 1. Modifying the water content. 
 
 2. Changing the color. 
 
 3. Changing attitude of surface. 
 
 4. Modifying texture and structure by cultural pro- 
 cesses. 
 
 VII. WEEDS IN THEIR RELATION TO PLANT CUL- 
 TURE. 
 
 They are usurpers of. 
 
 A. Moisture. 
 
 B. Food. 
 
 C. Light and heat. 
 
 D. Vitiate the product. 
 
 VIII. ADAPTATION OF CROPS TO SOILS. 
 
 Determined by. 
 
 A. Physical and chemical requirements of the plant. 
 
 a. Habit of growth and root development. 
 
 b. Knowledge needed regarding the specific requirements 
 of all our common plants with reference to moisture, 
 temperature and root development. 
 
 B. Ability of the soil to meet the needs of the plant. 
 
 a. Need of specific knowledge relative to the ability of 
 soils to supply these requirements. 
 
i8 
 
 Some examples in crop adaptation. 
 
 1. Grass crops. 4. Early and late truck. 
 Corn. 5. Celery. 
 
 Wheat. 6. Asparagus. 
 
 Blue grass. 7. Tree fruits. 
 
 2. Legumes. Apples. 
 Clover. Peaches. 
 
 Alfalfa. 8. Special crops. 
 
 3. Root crops. Tobacco. 
 Beets (sugar) Pineapples. 
 Potatoes. 
 
 IX. CROP ROTATION. 
 
 Reasons for. 
 
 A. Economy in management. 
 
 B. Eradication of noxious weeds. 
 
 C. Maintenance of proper physical properties of the soil. 
 
 D. To aid in correcting the physiological properties of the 
 soil. 
 
 X. THE CLASSIFICATION AND MAPPING OF SOILS. 
 
 A. General principles of classification. Division into. 
 
 a. Provinces. — Mode of origin. 
 
 b. Groups. Peculiarities of deposition. 
 
 c. Series. Relationships in formation. 
 Range of texture. 
 
 d. Types. Texture and structure. 
 
 B. Factors considered in mapping. 
 
 a. Texture. 
 
 b. Structure. 
 
 c. Origin. 
 
 d. Process of formation. 
 
 e. Climate. 
 
 f. Surface features. 
 
 g. CFop value. 
 
 C. Preparation of a soil map. 
 
19 
 
 D. Practical applications of a soil map. 
 
 a. Location of definite soil areas. 
 
 b. Establishing crop adaptation. 
 
 c. Collect practical agricultural experience over wide 
 area. 
 
 d. Solving problems of chemical and physical conduct. 
 
 e. Guide in experimentation. 
 
 f. Applying experimental results. 
 
 g. Estimating the value of land. 
 
 h. Establishing the conditions of habitation, 
 i. For purposes of general farm "management. 
 
 E. Extent, source and availability of soil maps in the United 
 
 States and other countries. 
 
 F. Application of the large scale soil map to the farm. 
 
 a. A practical guide in the scheme of farm management.