NRES 201 Lecture 3 Outline of Last Lecture I. What is soil?II. Soil ComponentsIII. Functions of soilIV. Soil as an environmental interfaceOutline of Current Lecture II. Introduction to soil physical propertiesIII. Soil colorIV. Soil textureV. Soil structureVI. Soil consistenceCurrent LectureI. The basic propertiesa. Color: described by hue, value, and chromab. Texture: size distribution of soil particles c. Structure: arrangement of soil particles to form aggregates or pedsd. Consistence: cohesiveness holding soil particles togetherII. Importance of soil physical properties:a. Direct effects oni. Water storage and flowii. Aerationiii. Temperatureb. Indirect effects oni. Plant species suitability and growthii. Nutrient availability iii. Pollutant transportiv. Erosionv. Tillage and compactionvi. Engineering applications (home/road construction)III. Soil Colora. Hue: Dominant spectral colors which varies by chartb. Value: Lightness or darkness of the grayscale mask applied to the hue. It decreases vertically, from pure white (10) to pure black (0)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.c. Chroma: Intensity or brightness of the hue which increases toward the right, where the hue is brightest.d. Range in soil color: From nearly black to nearly white. i. Variation with landscape position, profile depth, and ped aerationIV. Factors affecting soil color:a. Organic matter content i. Dark coatings on mineral surfacesb. Water contenti. Lowers color valuec. Presence of iron and manganese oxidesi. Well drained soils are bright red or brown (high chroma)ii. Poorly drained soils are gray or bluish (low chroma)V. Soil Texturea. Range of particle sizes: From boulders to fine clayb. Particle size groupsi. Sand - Feels gritty, individual particles visible to the naked eye, rounded or angular, composed mainly of quartz, very low in specific surface area, does not cohere to form aggregates, no stickiness or plasticity, low capacity to store water and nutrients.ii. Silt - Feels silky, like flour, individual particles invisible to the naked eye, low in specific surface area, highly susceptible to wind and water erosioniii. Clay - Individual particles invisible to the naked eye, sticky and plastic when wet, hard and cloddy when dry, tiny pores limit water movement and aerationVI. Changes in soil texturea. A very slow process during soil formation and weathering b. Artificial changes not feasible on a field scale i. Would require a massive input of soil with a different textureii. Adding sand to a fine - textured soil can produce concretec. Textural management more feasible for a gold green or athletic fieldVII. Structural grade and sizea. Grade refers to the distinctness of the peds i. Strong, moderate or weakb. Class refers to their sizei. Smallest size limits for spheroidal or plate - like structureii. Largest size limits for prism - like
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