SOILS CSENV 202
Popular in Course
Popular in Environmental Resource Science
This 7 page Class Notes was uploaded by Elian Feil on Saturday September 26, 2015. The Class Notes belongs to CSENV 202 at Clemson University taught by Yuji Arai in Fall. Since its upload, it has received 66 views. For similar materials see /class/214273/csenv-202-clemson-university in Environmental Resource Science at Clemson University.
Reviews for SOILS
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 09/26/15
Soils Study Guide Chapter 1 6 major functions of soil Medium for plant growth Systems for water supply and purification recycling system for nutrients and organic waste Habitat for soil organisms engineering medium modifier of the atmosphere Plant medium functions physical support for anchoring the root system Ventiliation of02 and C02 through pore space in soils Water39holding capacity via deep roots extension Insulation protect from heat damage Soils act as a modifier of the atmosphere When soils are dry they can be eroded by wind The evaporation of soil moisture major source of water vapor in the atmosphere affects air temp and composition and weather patterns Horizons 0 A E B C O litter or freshly added debris may be thin or nonexistent depends on vegetation A rich mineral particles and organic matter and darker in color than the rest 8 accumulation of weathered materials 4 major components in loam surface soils Mineral45 Air 2030 Water 2 03 0 Organic 5 Mineral Groups Primary Chemically not altered since its deposition and crystallization from molten lava Quartz Si02r Secondary one resulting from weathering of primary materials clays Kaolinite 3 major size classes Sand 2005 mm Silt 005 0002 mm Clay lt 0002 mm Soil Organic Matter organic carbonaceous rich in carbon substances including living organisms biomass and decomposed remains of organisms and plant matters acts a quotnatural glue to stabilize soil particles Macronutrients Carbon C Hydrogen H OxygenO Phosphorous P Potassium K Nitrogen N Calcium Ca Magnesium Mg Sulfur S Micronutrients Boron B Iron Fe Cobalt Co Chlorine Cl Manganese Mn Molybdenum Mo Nickel Ni Copper Cu Zinc Zn Soilair exchange at the soilatmosphere interface About 25 air contentin soils is an optimum condition for plants Ventiliation of air through the network of soil pore C02 and 02 exchange C02 in the air 0035 C02 in soils 0110 higher Nutrients are present in soil solutions and they are constantly replenished away 3 principal mechanisms for plant nutrient uptake Root interception Mass ow and Diffusion Once nutrients are available in soil solutions plant roots can uptake nutrient Via mass ow and diffusion at the rhizophere Soil Quality a measure of the ability ofa soil to carry out particular ecological functions Deggadation Anthropogenic inputs and mismanagement destroy the soil quality CH 4 3 Components of soil color provides properties and conditions Hue redness or yellowness Chroma Intensity or brightness Value lightness or darkness Causes of soil color Organic matter content high OM exhibits dark color Water content moist soil9 dark in color Presence of oxidized iron and manganese oxides decrease in water contentquot9 more soil air oxygen makes soil color more reddish Gley low chroma indicates the waterlogged history presence ofreduced iron Fe Soil texture is quotsize of distribution ofparticles Surface area is the unique relationship between particle size and surface area the smaller the particle size the greater the surface area 5 properties in uenced by surface area 1 water retention the greater the SA the greater the retention 2 Nutrient and other chemical retention the greater the SA the greater the retention of nutrients and contaminents 3 The greater the SA the greater the rate of release of nutrients from weatherable materials 4 The greater the SA the greater the particle attraction resulting in aggregation 5 The SA provides habitats and reactive sites for soil microbes Soil Textural Classes 3 broad groups depends on the distribution of sand silt and clay we classify the soil as Sandy soils Clayey soils and Loamy soils Loamy soils have the most class names Know how to read a textural triangle Stoke s Law V Kdquot 2 4 pes of Soil Structure Spheroidal Granular crumb Platelike Platy Blocklike Subtangularblocky Prismlike columnar prismatic Factors In uencing Soil Aggregation Physicalchemical processes attraction of clay particles swelling and shrinking of clay masses Biological processes burrowing and molding activity by earthworms and termites sticky networks of roots and fungal hyphae organic glue by microbes bacteria and fungi Role of organic matter major agent to stimulate the formation of aggregates can act as energy substrate for soil organisms decomposed organic polymer can bind clay particles resulting in organomineral complexes to promote the formation of aggregates Organic matter content in soils makes aggregates very stable Decomposed organic polymers can bind clay particles resulting in organic mineral complexes to promote formation of aggregates Know particle density and bulk density calculations estimate porosity Factors that affect bulk density More pore space yields in lowering bulk density The finer the texture of the soil the lower the bulk density quotHigh total pore space yields in lowering bulk density The uniform grain size and the packing arrangement of sand grains Depth in soil profile bulk density increases with increasing depth Soil management practice affect bulk density Forest due to dragging logs mtn biking trails Tilliage is a temporary solution to loosen soils longterm tilliage increases Bulk density due to depletion of OM less OM quot9 less aggregates Reasons for l 39 root growth in soils poor aeration structural resistance slow movements of nutrients and water build up oftoxic gases factors affecting root growth pore space availability soil strength Strength increases with increasing bulk density Factors in uencing Total Porosity Varies widely in different soils as low as 25 in compacted soils more than 60 in well aggregated soils Cultivation results in lower porosity 3 Types of Macropores Packing pores form between primary soil particles sand grains Interpeds Pores form between loosely packed granules or between blocky and prismatic peds Biop ores form by organisms earthworm and plant roots tubular in shape Micropores important for biological activity are found in interapeds retain water that plant can use accommodate most bacteria Consistence The resistance ofa soil to mechanical stress or manipulation at various moisture content measure by feeling or manipulating soils by hand Consistency The degree to which a soil resists the deformation when a force is applied determined by soil s resistance to penetration by a pencil Cohesive Soils 2 distinctive components a inherent electrostatic attraction force between clay particles and the water b frictional resistance to movement between soil particles of all size Noncohesive soilsusually sandy soils depends on entirely frictional forces Collapsible Soils exhibit the considerable amount of strength at low water content but they lose the strength if they become wet consist ofloose dry lowdensity materials cemented loosely by gypsum CH 5 Cohesion attraction of water molecules Adhesion attraction ofwater molecules on the solid surfaces Surface Tensions property of the surface of water causes it to behave as an elastic sheet Capillary Mechanism h cm 15r Understand this equation The capillary raise is less than one would expect because of tortuosity and entrapped air Height of rise Coarse texture soilsltltltltltltlt Finer textured soils 3 major forces affecting the energy level of soil water Matric force responsible for absorption and capillarity Osmotic force reduce the energy state of water in the soil solution Gravity pulls the water downward Gravitational Potential ng g h Pressure Potentials Hydrostatic qu Matric Potential qu Osmotic Potential quIt is attributable to the presence of both inorganic and inorganic solutes Na and ethanol in soil solutions The greater the solute conCentration the lower the osmotic potential Water moves in response to differences in osmotic potential only if semipermeable membranes exist Understand the relationship between the soil moisture content and the energy levels in kPa Understand the soil water versus energy curves as a function of aggregation and texture Hysteresis the unique relationship between the soil water potential and the soil water content when soils are drying or re wetting Expressinq soil moisture content Gravimetric Water Content Wt of wet soil wt of dry soil wt of dry soil Volumetric water content Volume of water cm3 volume of dry soil cm3 Volumetric water content total depth of soil Maximum Retention Capacity When all soil pores are filled with water saturated MRC and soil depth are used to predict how much water can be stored in a soil used to help avoid flooding downstream Field Capacity With no addition of water soil pores will begin to drain Water in largest pores drain first Air replaces water in macropores water movement occurs but it is now due to the capillary force Wilting Coefficient process to reach wilting point Soil is not completely dry at this stage water is still held in small pores held tightly by matric potential Hygroscopic coefficient The water content gets reduced via evapotranspiration and evaporation Water is tightly held by soil particles mostly absorbed on colloidal surfaces 3 types of water movement Saturated ow pores are filled with water Unsaturated ow large pores in soil are completely filled with air smaller pores hold and transmit water Vapor movement vapor pressure differences develop in relatively dry soils Water always ows from a zone of higher potential to one oflower water potential Darcy s Law Ksat QL delta H At cms Factors that In uence Hydraulic Condictivig Alteration of the size and configuration of soil pores Preferential ow water moves much faster than we predict Unsaturated Flow Most soil water movement occurs when soils are unsaturated movement occurs in a more complicated environment in which characterizes saturated water ow When the moisture content is low in soils hydraulic conductivity occurs at higher rates in clayey soils When there is higher moisture content in soil hydraulic conductivity occurs at higher rates in sandy soils Infiltration the process by which water enters the soil pore spaces and becomes soil water As pores are filled with water the infiltration rate levels off The rate is not constant over time It decreases with increasing time Percolation the movement ofwater within the soil downward through the soil profiles The rate ofpercolation is related to the hydraulic conductivity Stratified soil profile Water is applied to medium textured soils The downward movement ofwater stops when a coarse texture layered is encountered After 400 min the water content of the overlying layer becomes sufficiently high and the downward movement of water into the sand takes place
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'