Introductory Soils: Soil Profiles - Laboratory 2 | NRES 201, Lab Reports of Earth Sciences

Download Introductory Soils: Soil Profiles - Laboratory 2 | NRES 201 and more Lab Reports Earth Sciences in PDF only on Docsity! Introductory Soils Lab 2 Soil Profiles NRES 201 LABORATORY 2 DESCRIBING SOIL PROFILES Soil cores can be collected in the field with hand or power coring devices that retrieve undisturbed samples. A variety of information can be determined by a visual inspection of fresh and fixed soil cores in the laboratory. The profile is described by identifying the individual horizons that are present, their depth, color, structure, and texture. Other information about the soil which may also be determined from a visual inspection includes; parent material, natural drainage class, and soil classification. 2.1 SOIL HORIZONS 1. Depth (cm) - The mineral surface is assigned a depth of zero. Record depth to the center of the boundary separating each horizon from the one below, i.e., 0 - 15 cm, 15 - 30 cm, etc. Horizons thinner than 7.5 cm are not ordinarily described with the notable exceptions of E, Bh, and Bs horizons. 2. Texture - Standard name and abbreviations are used to describe the texture of each horizon. sand ------------ S silt--------------Si silty clay--------------SiC loamy sand ---- LS silt loam -------SiL sandy clay loam -----SCL sandy loam ---- SL clay loam------CL sandy clay ------------SC loam ------------ L clay ------------C silty clay loam -------SiCL 3. Color - Use the Munsell soil color book to determine the moist color of each horizon. Surface horizons should be crushed color, subsurface should be broken peds. Record the color using the hue value/chroma notation. a. Mottling - Mottling is the presence of more than one color due to impeded drainage. b. Coats – Ped coats can be of contrasting color due to translocated clay, carbonates, or organic matter. 4. Horizon name - See list and definitions of the master horizons and subordinate distinctions. Horizon Designations 1. The purpose of using horizon designations is to reflect the describer’s interpretations of the genetic relationships between the horizons in a soil. 2. Capital letters, lowercase letters, and Arabic numerals are used to form horizon designators. a. Capital letters are used to designate master horizons. b. Lowercase letters are used as suffixes to indicate specific characteristics of the master horizon. c. Arabic numerals are used as suffixes to indicate vertical subdivisions within a horizon and as prefixes to indicate lithologic discontinuities. Previously, Arabic numerals were used as suffixes to indicate a kind of O, A, or B horizon and to indicate vertical subdivisions of a horizon, and Roman numerals were used as prefixes to indicate discontinuities. The first parent material is assumed and therefore “1” is not used. e.g. loess over till: A, Bt1, Bt2, 2Bt3, 2BC, 2C d. A prime “ ‘ “ is used too indicate repeated designations, e.g. A, E, Bt, E’, Bx, BC, C Page 1 of 8 Introductory Soils Lab 2 Soil Profiles NRES 201 Common Master Horizons Old Current Situation O O Organic horizon A A Surface mineral horizon, “topsoil” A1 A First surface mineral horizon, “topsoil” A2 E Eluvial horizon, below A horizon A3 AB or EB Transitional horizon between A and B ----- E&Bt (lamellae) Found in sands B B Illuvial horizon, has subordinate distinction B1 BA or BE Transitional horizon between B and A B3 BC or CB Transitional horizon between B and C C C Unweathered parent material, massive, (calcareous) R R Bedrock Common subordinate distinctions within master horizons Old Current Situation --- a highly decomposed organic matter, used with O b b buried soil horizon, used with O, A, or B --- d dense layer, physical root restriction, used with B or C --- e intermediately decomposed organic matter, used with O g g strong gleying, used with E, B, or C h h illuvial accumulation of organic matter, used with B --- i slightly decomposed organic matter, used with O ca k accumulation of carbonates, used with B m m strong cementation, used with Bk na n accumulation of sodium, used with B p p plowing or other disturbance, used with A r r weathered or soft bedrock, used with C -- ss presence of slickensides, used with B, C t t accumulation of silicate clay, used with B --- w weak development of color or structure, used with B x x fragipan, used with B Page 2 of 8 Introductory Soils Lab 2 Soil Profiles NRES 201 Page 5 of 8 Laboratory Directions Name _____________________________________ Lab Section ___________________ Date _____________ 1. Complete a profile description sheet for the assigned soil cores in the laboratory. 2. Answer the following questions: a. How would recent alluvial materials differ from glacial outwash, lacustrine sediments, glacial till, or loess? How can you tell the age and origin of a parent material? _______________________________________________________________________________________ _______________________________________________________________________________________ _______________________________________________________________________________________ _______________________________________________________________________________________ _______________________________________________________________________________________ b. What would be the probable texture of a soil forming at the center of a dry lakebed? _______________________________________________________________________________________ _______________________________________________________________________________________ c. Identify the most common soil parent materials in: Northeastern Illinois. _______________________________________________________ Central Illinois. ____________________________________________________________ Southern Illinois close to horseshoe lake (Mississippi River flood plain). _________________________________________________________________________ South central Illinois in the vicinity of Vandalia. __________________________________ d. What would be the drainage class of a soil if the B horizon contains mottling and is gleyed? _____________________________________________________________________________ e. How would you identify a well drained subsoil? _____________________________________________________________________________ f. Why is there no loess on a floodplain? _____________________________________________________________________________ Introductory Soils Lab 2 Soil Profiles NRES 201 Introductory Soils Name _____________________________________ Lab Section ___________________ Date _____________ Profile Description Sheet Profile no. ____________________ Horizon lower depth (cm) texture structure color mottles (Y/N) _________ __________ __________ _________ _________ _________ _________ __________ __________ _________ _________ _________ _________ __________ __________ _________ _________ _________ _________ __________ __________ _________ _________ _________ _________ __________ __________ _________ _________ _________ _________ __________ __________ _________ _________ _________ _________ __________ __________ _________ _________ _________ Parent Material _______________________________________________________________ Natural Drainage Class _______________________________________________________ Page 6 of 8 Introductory Soils Lab 2 Soil Profiles NRES 201 Name _____________________________________ Lab Section ___________________ Date _____________ Profile Description Sheet Profile no. ____________________ Horizon lower depth (cm) texture structure color mottles (Y/N) _________ __________ __________ _________ _________ _________ _________ __________ __________ _________ _________ _________ _________ __________ __________ _________ _________ _________ _________ __________ __________ _________ _________ _________ _________ __________ __________ _________ _________ _________ _________ __________ __________ _________ _________ _________ _________ __________ __________ _________ _________ _________ Parent Material _______________________________________________________________ Natural Drainage Class _______________________________________________________ Page 7 of 8