NRES 201 1nd EditionExam # 1 Study Guide Lectures: 1 - 13IntroductionWhat is soil and how is it important? Soil is the surface layer of the earth, supporting plant life. How has soil exploitation led to erosion? Soil erosion has been caused by mismanagementWhen and where did the Dust Bowl occur? The Dust Bowl occurred in the 1930's in the eastern and mid-western states and then in the southern plains. What were black blizzards? They first appeared in 1935 from early March to April 14th "Black Sunday" and was severe through 1938. Due to it, there has been a serious loss of valuable topsoil, drastic decline in wheat and cattle output, health hazard, and abandoned farms and refugees.What has been the major type of soil erosion in Illinois? The damage has been done by water, not wind.Soils & Soil PropertiesWhere does soil occur and what are the two principal constituents? Soil is the upper part of the Earth's crust composed of mineral and organic matter and formed by the interaction of the five soil - forming factors.What are the fve soil forming factors?‐ Climate, organisms, topography, parent material, timeWhat is the solum and how does it differ from the regolith? Which horizons are included? Solum consists of three horizons/layers - O = organic, A = plow layer, B = subsoil. The C horizon is parent material, but not yet soil and is not included in solum. Regolith is (O+A+B+C). How does texture differ from structure? Texture is the proportion of particles by size: Sand (coarse), Silt (medium), Clay (fine). Structure is the aggregation of soil particles which is important to soil air and water movement as well as root growth. How is organic matter content important to soil properties and processes? Organic matter content has many important effects on soil physical, chemical, and biological properties, including: aggregation of soil particles, water storage and availability, microbial energy source, and nutrient - supplying power.What is the soil solution and where in the soil does it occur? The soil solution is (water + dissolved ions, molecules, and gases). It is held within the soil pores - mobile in large pores, but immobile in small pores. What is the soil atmosphere and how does it differ from ambient air? Soil atmosphere is when gases occupy soil pores that are not filled with water. It differs from ambient air by having: less O2, more CO2, and more humidity.What is a typical composition of a loam surface soil? Mineral: 45%, Air: 20 - 30%, Water: 20 - 30%, Organic: 5%What are the six functions of soil?1. Medium for plant growth2. Regulator of water supplies3. Waste recycling systems4. Habitat for soil organisms5. Engineering medium6. Atmospheric modifierWhich three nutrient elements are not supplied by soil minerals? Carbon, Hydrogen, OxygenWhat is the pedosphere and how is it important? The pedosphere is soil and it is the outermost layer of the Earth, where soil forms and life begins.How are hue, value, and chroma represented by the Munsell system? They all deal with color. Hue is the dominant spectral colors which vary by chart. Value is the lightness or darkness of the grayscale mask applied to the hue which decreases vertically. from pure white(10) to pure black(0). Chroma is the intensity or brightness of the hue. What effect does organic matter have on soil color? Organic matter content means the soil color will have dark coatings on mineral surfaces.What are the size ranges for sand, silt, and clay?Sand: (0.05 - 2mm)Silt: (0.002 - 0.5mm)Clay: (<0.002mm)What is meant by the term, loam? A mixture with equal properties of sand, silt, and clayHow do the textural classes differ in sand, silt, and clay content?Sand: Feels gritty, rounded or angular, very low in specific surface areaSilt: Feels silky, like flour. Low stickiness and plasticity. Clay: Sticky and plastic when wet, hard and cloddy when dry. Tiny pores to limit water movement and aeration.What are the different types of soil structure and where do they occur in the profle?1. Structureless: Single - grained, massive, loose sand or dust, very large clods and difficult to break2. Spheroidal: Granular or crumb, prominent in surface soils under grassland, key role of organic matter3. Plate - like: Horizontal peds or plates, found in surface and subsurface horizons4. Block - like: Angular (sharp edges) or sub - angular (rounded), usually found in B horizons, good for drainage, aeration, and root growth5. Prism - like: Columnar(rounded tops) or prismatic (flat tops), usually found in B horizons, most common in arid and semiarid regions.What soil properties affect consistence? Soil consistence is a qualitative property which is affected bysoil moisture content. It is completely characterized when evaluated for dry, moist, and wet soils.Soil FormationWhat is the original source of parent material for soil formation? Rocks.What are the four soil forming processes?‐ -Transformations - Chemical or physical changes in soil constituents Destruction or synthesis-Translocations - Movement of materials within or between horizons. Water is the transporting agent.-Additions - From external sources. Ex - Fallen plant leaves, sloughed - off roots-Losses - To the external environment. Ex - Leaching to groundwater, erosionWhat are the major mineral groups that make up rocks?-Igneous rocks -Originate from molten magma below the Earth's crust and forms by the cooling of volcanic lava. -Sedimentary rocks - Formed from igneous rocks. Sediments settle under water and recement and is the dominant type of rock.-Metamorphic rocks - They are formed from igneous or sedimentary rocks under extreme temperature and pressure. What are the two most abundant elements in the Earth’s crust? Oxygen and Silicone How does residuum differ from colluvium and alluvium?-Residuum: Derived from rock that weathers in place and has no transporting agent. It is often the parent material for older soils. -Colluvium: It is material moved by gravity and deposited at the base of steep slopes. They are poorly developed, and often lack horizons. -Alluvium: It is material deposited by flowing water. Where would you expect to fnd:‐ Alluvial fans: Formed by sudden descent in stream flow that deposits sediment at the base of a slope. They are often highly fertile and prone to flooding. ‐ Deltas: Formed at the mouth of some rivers, as sediments deposit from slow - moving water. It is an extension of the floodplain. ‐ Lacustrine