IntroductionSoils and Soil PropertiesSoil FormationThe Soil ProfileSoil ClassificationSoil Survey and Land UseSoil Physical PropertiesReview Questions for Hour Exam 1IntroductionWhat is soil and how is it important?- Soil is surface layer of earth, supporting plant life- Dirt – soil that is out of placeImportance of soil management:- To control soil erosion and maintain productivity by:o Conservation practiceso Crop rotationo Avoiding organic matter depletiono Proper nutrient and water managementHow has soil exploitation led to erosion?Mismanagement led to serious erosion in some historical areas and US such as the Dust BowlWhen and where did Dust Bowl occur?It first occurred in the 1930s at time of economic depression and drought. It happened first in eastern and Midwestern states and then in southern plains.What were the black blizzards?Dust storms that first appeared in 1935 from early March to April 14th, known as “Black Sunday”. It caused serious loss of valuable topsoil to East Coast andAtlantic Ocean and also drastic decline in wheat and cattle output. Okies and exodusters headed west as a result of this.What has been major type of soil erosion in Illinois?Erosion has been less obvious in Illinois. Damage has been done by water, not wind. Years of intensive tillage for row cropping converted soils to sediments. They are now dredged from Illinois River in Mud to Parks ProjectSoils and Soil PropertiesWhere does soil occur and what are two principal constituents?Soils occur in upper part of Earth’s crust. It is composed of organic matter such as living organisms (biomass), organismal remains (residues) and inorganic materials such as primary materials in original rock and secondary materials by weathering.What are five soil forming factors?Climate, organisms, topography, parent material, timeWhat is solum and how does it differ from regolith? Which horizons are included?True soil is solum. It includes E horizon and contains organic layer, plow layer, and subsoil (O + A + B). Regolith is unconsolidated material above bedrock (O + A + B + C). Regolith also consists of C horizon.How does texture differ from structure? Which one is affected by management structure?Texture is proportion of particles by size.- Sand (coarse)- Silt (medium)- Clay (fine)Structure is how solid particles make an aggregate. Structure is affected by management practices.How is organic matter content important to soil properties and processes?Organic matter has important effects on physical, chemical, and biological properties interacting- Binding soil particles together to make aggregates- Water storage and availability- Microbial energy source- Nutrient-supplying matterWhat is soil solution and where in soil does it occur?It is water and dissolved ions, molecules, and gases. It is held within soil pores. Itis mobile in large pores, but immobile in small pores.What is soil atmosphere and how does it differ from ambient air? It is gases that occupy soil pores not filled with water. It differs from air that it has less O2, more CO2, and more humidity than air.What is the typical composition of loam surface soil?A mixture with equal properties of sand, silt, and clayWhat are six functions of soil?1. Medium for plant growtho Plant supporto Aeration (O2 and CO2)o Supplies watero Insulator for root systemo Controls toxicitieso Nutrient supply – structural nutrients: carbon, hydrogen, oxygen (water and CO2)2. Regulator of water supplies3. Waste recycling system4. Habitat for soil organisms5. Engineering medium6. Atmospheric modifierWhich three nutrient elements are not supplied by soil minerals?Carbon, hydrogen, and oxygenWhat is pedosphere and how is it important?Pedosphere: soil it important because it is outermost layer of earth where soil forms and life beginsHow are hue, value, and chroma represented by Munsell system?Hue – Munsell color charts- Dominant by spectral colors- Varies by charto Red is firsto Brown = nexto Yellow = lastValue - Lightness or darkness of grayscale mask applied to hue- Decreases vertically, from pure white (10) to pure black (0)Chroma- Intense or brightness of hue- Increases toward right, where the hue is brightestWhat effect does organic matter have on soil color?Organic matter content means dark coatings on mineral surfacesWhat are size ranges for sand, silt, and clay?Sand (0.05-2.0 mm) Silt (0.002-0.05 mm) Clay (< 0.002 mm)What is meant by the term loam?A mixture with equal properties of sand, silt, and clayHow do textural classes differ in sand, silt, and clay content?Sand- Feels gritty- Individual particles visible to naked eye- Round or angular- Composed mainly of quartz (SiO2)- Very low in specific surface area- Does not cohere to form aggregates- Low capacity to store water and nutrients- No stickiness or plasticity (cannot be molded)Silt- Feels silty, like flour- Cannot see particles in naked eye- Low in specific surface area- Limited capacity to store water- Highly susceptible to wind and water erosion- Limited capacity to store water and nutrientsClay- Particles invisible to naked eye- Sticky and plastic when wet- Hard and cloddy when dry- Moderate to high in specific surface area- High capacity to store water and nutrients- Tiny pores limit water movement and aerationWhat are different types of soil structure and where do they occur in profile?- Structureless – single-grained: loose sand or dust- Massive – very large clods difficult to break- Spheroidalo Granular or crumb (more porous)o Prominent in surface soils under grassland, where earthworms have been activeo Key role in organic mattero Conductive to plant growtho Greatly affected by soil management- Plate-likeo Horizontal peds or plateso Found in surface and subsurface horizonso Possible origins Soil-forming processes (most common) Parent material (water- or ice-laid) Mechanical compaction of clayey soils- Block-likeo Angular (sharp edges) or sub-angular (rounded)o Usually found in B-horizonso Good for drainage, aeration, and root growth- Prism-likeo Columnar (rounded tops) or prismatic (flat tops)o Usually found in B-horizonso Most common in arid and semi-arid regionsWhat soil properties affect consistence?Soil moisture content completely characterized when evaluated for dry, moist, and wet soilDry Consistence- Rated as loose, soft, slightly hard, hard, very hard, or extremely hard- Increased by clay- Decreased by organic matter- Important to root penetration and tillageMoist