ESS 210 Exam One
ESS 210 Exam One ESS 210 001
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This 5 page Study Guide was uploaded by Michaela Humby on Monday February 1, 2016. The Study Guide belongs to ESS 210 001 at University of Tennessee - Knoxville taught by Andrew Conrad Sherfy (P) in Fall 2015. Since its upload, it has received 96 views. For similar materials see Intro to Soil Science in Environmental Science at University of Tennessee - Knoxville.
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Date Created: 02/01/16
Exam 1 Study Guide Spring 2016 This guide is an overview of material you can anticipate seeing covered on this exam. Intro to Soils 1. What do soils do? Provide and promote growth of higher plants Engineering medium Principle factor in fate of hydrologic cycle Serves as nature’s recycling system Home to tremendous biodiversity 2. What are the five soil forming factors? Be very familiar with these and how each individual determines or influence how a soil forms. Factor One : Parent Material : Residual Parent Materials RESIDUUM ¨Soils develop on underlying bedrock ¨ Type of rock strongly influences type of soil ¨ Colluvial materials/ colluvium are carried by gravity, poorly sorted fragments of various sizes, and by small geographical areas (bottoms of hill slopes) ¨ Alluvial deposits and where in floodplains where during flooding, water spreads and slows. Sediment is dropped. Terraces are old floodplains above the current floodplain; Alluvial fans: Usually gravelly/stony in mountainous regions.Stream leaves narrow upland channel, descends to broad valley below Delta deposits: Rivers carry much clay/fine silt to lake or ocean. Very slow water = deposition. Very clayey, swampy ¨ Marine Sediments coastal plains; ocean sediments build up over time. Materials are gravely, sandy, clayey depending on area ¨ Lacustrine Sediments clayey soils formed in old lake beds; major areas are in glaciated areas ¨ Glacia Till and Outwash As glacier advances, grinds up rock and carries it. Glacial Till is UNSORTED, unconsolidated material. Deposited as glacier melts and recedes.T ill deposits called moraines. As glaciers melt, glacial rivers and streams form Glacial Outwash; SORTED deposits ¨ Eolian Deposits loess deposits wind blown material (mostly silt) from glaciated areas; cover FACTOR 2: Topography affects amount of water soil “sees” concept of effective precipitation FACTOR 3: Biota Plants, animals, microorganisms,( chemical weathering, OM accumulation, Aggregation FACTOR 4: Climate Temperature + precipitation= WEATHERING (= soil age) FACTOR 5: Time Works in concert with the other factors Chronologically old soil may be developmentally young(ex: arid soils, little development) 3. What are soils made of/ what is their composition? 4. What are all the types of parent material classes? Why is knowing the parent material important? 5. What is the definition of a pedon, profile and horizon? Pedon: the smallest 3D body of soil that allows determination of all soil properties of THAT soil. UNIQUE SOIL INDIVIDUAL Every unique pedon has a descriptive profile Vertical section of soil exposing all layers of the soil. Soils vary in number of layers and their thickness. Every profile is made up of layers or “horizons”. Horizons differ in properties from layer above and below it. Most profiles have several horizons. 6. Be familiar with the terms regolith, solum, parent material and bedrock. o Solum is typically made of the A and B horizons, no parent material o Regolith is all unconsolidated material down to the bedrock(A B and C) C is usually the parent materials but remember that its not soil or rocks because it does not have structur Soil Physical Properties 7. Understand the concept of soil color as an important diagnostic characteristic of soil. What are some examples of what color can tell you about a soil? Black organic matter White high silica content OR salts. Grey REDUCED IRON (Fe ), indicates poor drainage, saturated conditions, low oxygen. Reds, yellows, tans OXIDIZED IRON (Fe ), good drainage, adequate oxygen. 8. Know the terms matrix, mottle, hue, value, and chroma. Be able to recognize and understand Munsell notation. ∙ Mottling o Mixture of different colors o Bright colors mixed with greys means drainage problems Matrix vs mottle ∙ Matrix is the dominant color and mottle is the lesser color ∙ Depth to grey mottles redox features (redoximorphic) ∙ Well drained is greater that 30 inches ∙ Moderately well drained is 18 to 30 inches ∙ Somewhat poorly drained is 1018 inches ∙ Poorly drained is 1018 inches (grey matrix with brown mottles ∙ Very poorly is all grey o Used to communicate color consistently based on 3 properties 1. Hue spectral color of the rainbow: 10YR means 10:1 mix of yellow to red 2. Value is the amount of black or lightness added to color(0 blacck or 10 white) 3. Chroma brightness or purity; 1 high grey=low purity and 8 low grey= high purity. 2 or less indicated poor drainage. a. Grey or gleyed conditions” 9. What is soil texture? What defines a soils texture? What are the USDA textural size classes? Why is it important? Be able to use a USDA textural triangle. Soil Texture ∙ Percentage of sand, silt, and clay in a soil ∙ Does not include organic matter ∙ Permanent characteristic of soil (Cannot change the texture of a soil o Sand :0.05 to 2mm in diameter (single grain, gritty) o Silt: 0.0020.05 mm diameter (smooth, slightly cohesive, floury) o Clay: <0.002 mm (stiff, sticky, very cohesive) o EVERYTHING IS CLASSIFIED AS EITHER SAND SILT OR CLAY IMPORTANCE OF TEXTURE ∙ Water holding capacity ∙ Water movement into and off soil ∙ Resistance to erosion ∙ Engineering applications ∙ Nutrient holding capacity Influences crop management 10. What is soil structure? What are the structural classes? Why is structure important? Soil Structure: ∙ Aggregation of primary soil separates into compound particles that are separated from adjoin aggregates by planes of weakness ∙ Individual aggregate = ped= structural unit 1. Granular rounded or spherelike a. Surface soil (as organic matter increases, granulation increases) b. Soil mixed by roots, animals, temperature c. Typical of A or surface horizons d. The organic matter makes it more held together or glued 2. Platy flat, elongated a. Organized in thin plates b. More wide than it is tall c. Fluctuating water table, freezethaw, machine traffic d. Human impact 3. Prismlike tall, relatively narrow a. More tall than it is wide b. Rounded top is called columnar c. Flat top is called prismatic d. Shrinkswell causes vertical crackers e. The structures are still intact 4. Blocky roughly cubic (B horizon) a. Angular blocky more edges intact/defined b. Sub angular blocky –less defined edges c. More or less equal dimensions d. Prisms crack horizontally to for the blocks Structure Conditions o Structureless, single grained: no cohesion, such as in a beach sand o Structureless, massive: all primary separates are cemented or bound together in one mass without any natural planes of weakness (mainly common in the C horizon)where the parent material is § Parent material isn’t rock or soil because soil is defined as having structure and development ∙ Structure helps o Determine drainage of soil o Aeration of subsoil o Influences erosion o Rooting medium How do you manage good structure versus poor structure? ∙ Management of Aeration o Drainage (surface and tile drainage which is artificial) o Tillage (disrupt structure) can’t change texture but you can change structure o Leave as wetlands, forest, 11. What is particle density? What is bulk density? What factors affect bulk density? What are the typical values of these for soil? What is soil porosity a measure of? What changes porosity? What is pore size distribution, and what is an optimal one? How do you calculate bulk density? How do you calculate porosity? Why are porosity and bulk density important? What is the relationship between porosity/bulk density and structure/texture? ∙ Density is mass/volume ∙ Water is 1 g/cm^3 ∙ Density of soil is almost always going to be 2.65 g/cm^3 Because of the dominant minerals in soils (the quartz) ∙ Particle Density = Pd (dry soil weight (g) / (volume of soil solids) and Pd unless otherwise stated will always be 2.65 g/cm^3 ∙ Bulk density =Pb (dry soil weight/total volume of soil sample) o Density of soil in natural state, including pore space and organic matter, o Oven dry sample weight used o As pore space increases, density decreases and vice versa ∙ Soil % pore space o Volume of soil occupied by air and water o Depends on structure and texture o If we know pd and b then we can calculate the %. o E= 1 (Pb/Pd); as density increases porosity decreases. 12. How do organic matter, bulk density and structure vary by depth? ¨Soil Depth Subsurface horizons > surface ;Due to OM, compaction, blocky vs granular ¨OM content ¤High OM = lower P b ¨Texture ¤coarse > fine ¨Structure ¤good structure < poor structure ¨Traffic increases p b machinery; animals (yes humans too!) Roots penetration: ¤ rb 1.6 g cm 3 ¤Range for mineral soil: 1 2 g cm 3 ¨Other factors equal, yields ↑as r ↓ b ¨Plant disease higher with higher r b ¨High r ib fine texture ¤low macroporosity = poor drainage and/or low O availability 2 ¨Low r b ¤better macro + micropore distribution
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