Notes for Tomorrow's quiz
Notes for Tomorrow's quiz PSS 3303
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This 10 page Class Notes was uploaded by Payton Gilmore on Tuesday September 6, 2016. The Class Notes belongs to PSS 3303 at Mississippi State University taught by Dr. Jac J. Varco in Fall 2016. Since its upload, it has received 22 views. For similar materials see Soils in plant and soil sciences at Mississippi State University.
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Date Created: 09/06/16
CH 3. CONT. Soils samples are taken in pits Alfisol: o A o E o Bt1 o Bt2 o Bt3 o C o R o >35% BASE SATURATION - Located mainly in Texas and Midwest - Dominant Suborders o Aqua: high in moisture o Cry: cold o Uda: humid o Usta: dry and hot o Xer: dry summer and wet winters Aridisol: o A o Bt o Bk o Btn o C - No Aridisols in MS - Mostly in western US - Dominant Suborders: o Arg: o Calc: Calcium o Dur: o Gys: Gypsum o Sal: Sodium Entisol: o A o C o R - Occur everywhere - Youngest - River bottoms - Dominant Suborders: o Flu- flooding o Psa- 1-2 meters of sand (good for corn) Histosol: o Oa, e, or i o C o R - Everglades - Vegetable growing area - NY Subsidence Post Everglades Research and Education Center Buried in 1924 9’ to bedrock, 1924-1967 1.0”/y: 1967-2008 0.55”/y of subsidence. 2 o Sunk down to limestone o Soil decomposed over the years o Post was completely under the soil in 1924 o .55”-1.00” a year of sinking Inceptisol: o Ap o Bw o C - Young - Color - Appilachians and Rocky Mountains Mollisol: o Ap o Bt o C o R-Bedrock - West/Prairies - Not forest vegeatations - National security lies here - Main food source Oxisol: o A o Bo o C - Oldest soil - None in contential US - Hawaii 3 - Puerto Rico - Iron oxide Spodosol: o A o E o Bhs o C - Salt and Pepper look - Wisconsin and FL Soils are ALWAYS changing Ultisol: o Ap o E o Bt1 o Bt2 o Bt3 o C o R o <35% base saturation - South eastern US - Udults is most abundant Ultisol - Higher rain fall - Forested Alfisol is the best soil for farming… more fertile Vertisol: o Ap o Bss 4 o C o R - Black - Shrink, swell and crack - MS Delta - Blackland Prairie Andisol: - Oregon/NW - Volcanic areas - Mnt. St. Helens Timeline Image on Powerpoint Delta-entisols, inceptisols, alfisols, vertisols Loess- inceptisols, alfisols, entisols Coastal Plain- alfisols, entisols, ultisols Blackland Prairie- vertisols, mollisols, alfisols, inceptisols Interior Flatwoods- alfisols, vertisols, ultisols Coastal Flatwoods- spodosols, ultisols, histosols, entisols Examples of Soil Classifications in MS (Series Name/Subgroup): \ Memphis silt loam-Typic Hapludalf Dubbs silt loam-Typic Hapludalf Dundee loam- Typic Endoaqualf Lakeland sand- Typic Quartzipsamment TABLE 3.4 IN BOOK 5 To learn more and get OneNote, visit www.onenote.com. 6 CH. 4 PHYSICAL PROPERTIES: Soil Productivity Water holding capacity and drainage Construction suitability SOIL TEXTURE: Fine earth fraction, excludes pebbles, rocks, etc. The diameter of a particle determines which of the soil separates it is. The USDA classification is as follows: FIG. 4.1, PG. 98 IN BOOK Soils are approximately 45% by volume mineral matter. Relative proportions of sand, silt, and clay (soil separates) comprise or determine the texture of a soil. SEE FIG. 4.2, PG. 99 Decreasing particle sizeSurface area increases. Adsorption of water, gases, and nutrients and a greater attraction of particles to each other greater. (also faster weather, ^ swelling, plasticity, and cohesion) Sand and Silt Particles don’t stick together FIG. 4.3 PG. 99 SOIL TEXTURE GENERALIZATIONS: Clay Soils o Hold > H2O than coarser textures o Hold > nutrients than silt and sand o Adsorb > gases such as NH3 o Develop > structure Sandy Soils o > permeability to air and water o Lower water and nutrients o Lower in organic matter o Less developed structure SOIL TEXTURE TRIANGLE- 12 TEXTURAL CLASSES SEE FIG. 4.4, PG. 101 Loam best soils to garden o Less clay Soybeans are grown on clay Cotton- silt loam SOIL STRUCTURE Arrangement of individual soil particles into larger units. Units of soil structure- peds or aggregates; natural groups of soil separates, occur and persist within the soil o Many soils in the Delta have lost OM and SS is down CLASSIFICATION OF SOIL STRUCTURE A. Grade 1. Weak- aggregates too weak to remain intact upon removal 2. Moderate- remain intact when removed from soil, but can be crushed 3. Strong- visible in undisturbed soil, break into whole peds when removed from profile. Difficutly in crushing. 4. Structure-less- no observable aggregation, no natural planes of weakness. - Single grain in non-coherent 2 - Massive if coherent- commonly found in C horizons/parent material B.Class o Size of ped or aggregate a. Fine b. Medium c. Coarse C.Type o Shape of peds, natural planes of weakness 1. Spehrical- round in shape - Granular: porous - Crumb: very pourous o Good aeration, drainage, and highly desirable for plant growth. A horizons especially under grassland conditions. 2. Platy-peds with greater horizontal dimensions than vertical - Usually found in A E horizons. Related to parent material, frost action, water table fluctuations, and horizontal water movement. 3. Prism-like- dimensions greater in the vertical than horizontal - Prismatic: square tops - Columnar: rounded tops o B horizons well-developed soils. Most common in aridisols. Fragipans of MS. 4. Block-like- equal size in 3D - Angular blocky - Subangular blocky 3 o Common in B horizons - Ex. Strong, medium, subangular blocky Fig. 4.8, pg. 106 GENESIS OF SOIL STRUCTURE 1. Physical processes-orientation of soil particles - Wetting and drying - Freezing and thawing - Root action - Action of soil organisms - Textural influences 2. Biological - Plant root exudates - Microbial by-products - earthworm activity To learn more and get OneNote, visit www.onenote.com. 4