OBSERVING SOIL PROCEDURE Using a shovel, soil probe, or soil auger, collect a soil profile. (Go as deep as you can with the equipment). Arrange the soil you remove from the ground on newspaper or in a soil trough, in such a way as to maintain the orientation of the pieces. Identify all of the properties on the lists below and fill in the Soil Profile Description for those properties. Evaluate two profiles per lab group. Description Guidelines : I. SITE DESCRIPTION: a. DATE: Day, Month, Year b. PROFILE IDENTIFICATION AND LOCATION:: Give a name or number to the profile and use a GPS to give coordinates of the site location. describe the site. (Include the datum). Give the name of the topographic quadrangle on which the site is found. c. SLOPE POSITION: Compare site location to diagram: d. SLOPE ANGLE AND ASPECT: Using a compass and clinometer,determine the aspect, the direction the slope is facing, in degrees and the slope angle in %. e. VEGETATIVE COVER: Identify vegetation type (e.g., grassland, hardwood forest) and abundance (sparse, adequate, abundant). II. PROFILE DESCRIPTION: a. OVERALL PROFILE DEPTH: Assess the depth to the first restrictive layer, which can be a tree root, a rock or an file:///c /Web%20Page/pfarrell/Soils/Soil%20Lab%20Files/OBSERVING%20SOIL_files/OBSERV%20procedure.htm (1 of 4) [9/1/2008 2:31:24 PM]
impenetrable layer. DON'T GIVE UP TOO EASILY! b. TEMPERATURE: Use the soil thermometer to take the soil temperature in degrees Celsius. record the depth at which the temperature was taken (the tip of the thermometer). THE REMAINING PROPERTIES SHOULD BE DESCRIBED FOR EACH HORIZON: a. HORIZONATION: Observe color, structure, or texture changes from the surface downward. Assign a new master horizon name whenever a change occurs. Designate master horizons with capital letters O, A, E, B, C, R, according to the definitions below. O horizon: zone of litter or organic accumulation on top of soil. A horizon: uppermost mineral layer having accumulated humus, dark color, maximum biological activity, most intense mineral weathering. (Loss of A indicates erosion). E horizon: zone with extensive removal of clay and organic matter, lighter in color than layers above and below, usually acidic and infertile. B horizon: zone of accumulated clay, organic matter, iron and aluminum oxides, and calcium carbonate. Lack of a B horizon indicates a young soil with limited development. C horizon: parent material that is not affected by soil formation processes and lacks the definitive properties of the horizons above. R horizon: bedrock. b. HORIZON DEPTH: Give the depth of each horizon in centimeters, for example 0-4 cm. c. AERATION: Rate the horizon's aeration as "Well", "Adequate" or "Poor" in the checklist. (This can only be seen in "intact" pieces of the soil. Do not crumble the soil in your hand before examining aeration.) A direct method is to use a hand lens to examine a soil core for amount and continuity of the largest pores. Indirect methods include: (1) looking for abundant, fine, white roots which suggest adequate aeration; (2) red, brown, or tan colors that confirm good aeration, or gray or yellow colors thatdenote poor aeration and (3) well-aggregated soils that are good for aeration. d. STRUCTURE : Try not to compress or crumble the soil before you determine structure. Use the diagram below, showing some simple soil structures, to determine the structure (shape) of the soil clumps. Choose the structure which best describes the horizon you are observing. If there are two structures present, choose both. file:///c /Web%20Page/pfarrell/Soils/Soil%20Lab%20Files/OBSERVING%20SOIL_files/OBSERV%20procedure.htm (2 of 4) [9/1/2008 2:31:24 PM]
e. COLOR: Use the Munsell Soil Chart to identify soil colors. Hold the piece of soil behind the page with the sun at your back, find the color chip that EXACTLY matches the soil s color. The pages represent hues, the rows designate value, and the columns represent chroma. Munsell colors are always designated in the order of hue (page number), value (number in the left-hand column), and chroma (number across the bottom of the page). Write in the soil color as a hue-value-chroma, for example: 10YR 3/2. Next, look at the opposing page and give the verbal description, for examle: "very dark grayish brown". f. ROOTS AND PORES: Use a hand lens to directly examine soil for abundance and size of pores. Red, tan or brown colors and an abundance of roots are good indicators of adequate porosity. Gray or yellow colors indicate low oxygen levels, perhaps caused by low porosity, or a lack of large pores. Compaction can also indicate low porosity. Describe the quantitiy of roots as "Few", "Common", or "Many". Describe the quantitiy of pores as "Few", "Common" and "Many". Also, describe the sizes of roots and pores: "Very Fine" (<1mm) ; "Fine" (1 to <2 mm); "Medium" (2 to <5 mm); "Coarse" (5 to < 10 mm); "Very Coarse" (> 10 mm) g. TEXTURE: Use the flow diagram to determine the textural class of each horizon. ROCKS AND SAND : If there are rocks in the profile(larger than sand), you should give the proper size category: file:///c /Web%20Page/pfarrell/Soils/Soil%20Lab%20Files/OBSERVING%20SOIL_files/OBSERV%20procedure.htm (3 of 4) [9/1/2008 2:31:24 PM]
"gravel": 2 mm - 76 mm; "cobbles" : 76-250 mm; "stones" : 250-600 mm and "Boulders": >600 mm If there is abundant sand in the profile, you should describe the sand size, using the magnifying lens and the sand chart. Excessively moisten the soil and rub it around on the palm of your hand. examine the soil and the sand chart with the magnifying lens and determine the proper sand size from the chart. h. WATER-HOLDING CAPACITY : This is based on the texture class that you determine above. You can rank plant available water according to the following scale: Very low: sand, loamy sand, sandy loam, loam Medium: silt loam and silt, sandy clay loam, clay loam High: silty clay loam, clay, silty clay, sandy clay i. CONSISTENCE: Consistence gives the adhesive and cohesive properties of a soil. "Stickiness" is the capacity of soil to adhere to other objects. "Plasticity" is the degree to which reworked soil can be deformed without rupturing. STICKINESS : Moisten soil and press between thumb and forefinger. Use the following criteria to determine stickiness: Little or no soil adheres to fingers, after release of pressure: "n-sticky Soil adheres to both fingers, after release of pressure. Soil stretches little on separation of fingers: "Slightly Sticky" Soil adheres to both fingers, after release of pressure. Soil Stretches some on separation of fingers: "Moderately Sticky" Soil adheres firmly to both fingers, after pressure release. Soil stretches greatly upon separation of fingers: "Very Sticky" PLASTICITY : Form a "worm" of soil (4 cm long) so that the soil is the most plastic you can make it. Then see how thin the worm can be and still stay intact. Use the categories below to determine plasticity: If the soil will not form a worm 6 mm in diameter or, if formed, it will not support itself on end: "n-plastic" If the 6 mm worm supports itself, but a 4mm worm does not: "Slightly Plastic" If a 4 mm worm supports itself, but a 2 mm worm will not : "Moderately Plastic" If a 2 mm worm supports its own weight: "Plastic" file:///c /Web%20Page/pfarrell/Soils/Soil%20Lab%20Files/OBSERVING%20SOIL_files/OBSERV%20procedure.htm (4 of 4) [9/1/2008 2:31:24 PM]
Start Soil Texture By Feel Flow Chart Place approximately two teaspoons of soil in your palm. Add a few drops of water and kneed soil to break down all the aggregates Soil is at proper consistency when it feels plastic and moldable, like moist putty. Add dry soil to soak up water Does the soil remain in a ball when squeezed? Is the soil too dry? Is the soil too wet? Sand Place ball of soil between thumb and forefinger, gently pushing the soil with your thumb, squeezing it upward into a ribbon. Form a ribbon of uniform thickness and width. Allow the ribbon to emerge and extend over forefinger, breaking from its own weight. Does the soil form a ribbon? y Sand make a weak ribbon < 1" long before it make a medium ribbon 1-2" long before it make a strong ribbon > 2" long before it Excessively wet a small pinch of soil in your palm and rub it with your forefinger. HI % S A N D Silt Silty Silty LO % CLAY HI