Transcript Slide 1
Delineating Soil Horizons Soil as a Natural Body Differentiation Additions Losses Parent Material Translocations Transformations Bedrock Bedrock Soil Horizons Roughly parallel layers in the soil with varying composition and properties Master Horizons Criteria for Characterizing Soil Horizons Color Texture Density Structure Organic matter Mineralogy Chemistry Soil Color Soil Color Determinants • • • • • Mineralogy of the soil/parent material Relative amount of organic matter Hydrology of the soil Soil chemistry Soil Microbes Coloring Agents in Soils Organic Matter Grey to Black coloration particularly in topsoil or A horizon material. Can be found in the sub-soil as an accumulation Elements and Compounds Iron, manganese Reddish to yellow-brown Purplish black Soil Color Determination Munsell Soil Color Hue Value related to total amount of light reflected. dominant spectral color; related to the wavelength of light. Related to the proportions of red to yellow. In soils we only use 1/5 of the color chips available. Chroma measure of the strength of spectral color 10R 0 2.5YR 5YR 7.5YR 10YR 0 2.5 Y 5Y Hue Pages 10 R Red 2.5 YR 5 YR 7.5 YR 10 YR 2.5 Y 5Y Yellow Increasingly dominated by yellow spectral color Florida soils dominated by 7.5 YR and 10 YR pages Soil Color Hue = 10 YR Value = 6 Chroma = 3 Munsell Color 10 YR 6/3 10 YR 2/1 10 YR 5/6 Pink Pale Red Weak Red light Red Red Dark Red Summary A horizon – mid/low value - low chroma E horizon – high value - low chroma B horizon – ? value - ? chroma Water table depth Oxygen status Development decisions Hydric Soil Classification Hue 10YR or Yellower Value ≤3 Chroma ≤1 “Black Histic” Mineral Formula Size Munsell Color goethite FeOOH (1-2 m m) 10YR 8/6 yellow goethite FeOOH (~0.2 m m) 7.5YR 5/6 strong brown hematite Fe2O3 (~0.4 m m) 5R 3/6 red hematite Fe2O3 (~0.1 m m) 10R 4/8 red lepidocrocite FeOOH (~0.5 m m) 5YR 6/8 reddish-yellow lepidocrocite FeOOH (~0.1 m m) 2.5YR 4/6 red ferrihydrite Fe (OH)3 2.5YR 3/6 dark red glauconite K(SixAl4x)(Al,Fe,Mg)O10(OH)2 5Y 5/1 dark gray iron sulfide FeS 10YR 2/1 black pyrite FeS2 10YR 2/1 black (metallic) jarosite K Fe3 (OH)6 (SO4)2 5Y 6/4 pale yellow todorokite MnO4 10YR 2/1 black 10YR 2/1 black humus calcite CaCO3 10YR 8/1 white dolomite CaMg (CO3)2 10YR 8/2 white gypsum CaSO4× 2H2O 10YR 8/3 very pale brown quartz SiO2 10YR 6/1 light gray Low Value Low Value High Value Low Chroma high Chroma Criteria for Characterizing Horizons Color Texture Density Structure Organic matter Mineralogy Chemistry See the Teaching Assistants Before Leaving: Jon Demps Melissa Odal Grant Baysinger Daniel Kristiansen Markihe Anderson Percy Harvin Also anyone who has not received a student number