Soil horizon

{
  "id": "MLC-T-ENV-025994",
  "term": "Soil horizon",
  "field": "Environment",
  "term_source": "Soil Horizon",
  "definition": "1. A soil horizon is a layer that is commonly parallel to the soil surface. In some orders, such as Gelisols, Vertisols, and Spodosols, however, horizons are not always parallel to the surface. A horizon has some set of properties that have been produced by soil-forming processes, and it has some properties that are not like those of the layers directly above and beneath it (USDA, SCS, 1993). A soil horizon commonly is differentiated from the horizons adjacent to it partly by characteristics that can be seen or measured in the field, such as color, structure, texture, rupture-resistance class, and the presence or absence of carbonates. In identifying a soil horizon, however, measurements in the laboratory are sometimes required to supplement field observations. According to the criteria we use, horizons are identified partly by their own morphology and partly by properties that differ from those of the overlying and underlying horizons.\n\n2. Means contrasting layers of soil parallel or nearly parallel to the land surface. Soil horizons are differentiated on the basis of field characteristics and laboratory data.\n\n3. Layers of soil that are distinguishable by characteristic physical or chemical properties.",
  "subject": "Natural environments",
  "references": [
    "USDA Natural Resources Conservation Service Soil Taxonomy A Basic System of Soil Classification for Making and Interpreting Soil Surveys (1999)",
    "EPA Mountaintop Mining Valley Fills Draft Environmental Impact Statement Glossary at http://www.epa.gov/region3/mtntop/pdf/VIII_Glossary.pdf",
    "NOAA Coastal Services Center Glossary of Coastal Terminology"
  ],
  "url": "https://mlchart.com/terminology/environment/soil-horizon/"
}