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Soil Does More Than Get You Dirty - Short Course on Soils

How Much Longer Can We Afford to Treat Our Soils Like Dirt?

A short, short course for elementary school teachers developed by Orville Bidwell, Department of Agronomy, Kansas State University, Manhattan, Kansas 66506. January 1990

  1. Definitions
    1. Dirt - Filth, grime, gossip, SOIL
    2. Soil - Surface layer of the earth that consists of SAND, SILT, and CLAY that support plant life.
      1. Sand - Coarse, gritty particles. Identifiable minerals. Examples: Hourglass sand, beach sand, sandpaper.
      2. Silt - Intermediate-size particles; not gritty. Silt clods soft, easily breakable when dry; silt, not shiny or sticky when pressed between thumb and forefinger, moist.
      3. Clay - Fine particles. Clay clods hard and unbreakable when dry; produce a smooth, shiny ribbon moist when rubbed between thumb and fingers.
        Blackboard example to compare particle size of sand, silt, and clay
  2. Soils, like adult human beings, are the produce of Heredity, Environment, and Time.
      Humankind Soils
    Heredity Parent's Genes and Chromosomes Parent Material, Geologic materials of weathered bedrock or deposits of wind, water, or ice.
    Environment Acquired knowledge and experience at home, play, and school.

    Climate (temperature and moisture)

    Land Slope affects water intake, runoff, and erosion.

    Climate influences weather, loss of fertility, and type of vegetation.

    Vegetation - Forest, prairie grassland, or desert shrubs.

    Time   Time
  3. Some influences of the five soil-forming factors

    1. Parent Material:

      • Sandstone weathers to sandy soils.

      • Shale and limestone weather to clayey soils.

      • Deposits of wind produce silty soils.

      • Deposits of water produce gravelly, sandy, silty, and clayey soils.

      • Deposits of ice produce cobbly, gritty, and gravelly soils.

    2. Land Slope:

      • Steep slopes produce rapid runoff and erosion.

      • Moderate slopes produce moderate runoff and erosion.

      • Level slopes produce little runoff and erosion and maximum penetration of moisture.

    3. Climate:

      • High temperature and moisture produce rapid weathering and chemical fertility loss known as leaching.

      • Low temperature and moisture produce slow weathering and leaching.

      • High moisture produces forest vegetation.

      • Intermediate moisture produces grassland prairie vegetation.

      • Low and inadequate moisture produces desert shrub vegetation.

    4. Vegetation: Influences Soil Color, Organic Matter, and Chemical Fertility


      Soil Color

      Organic Matter

      Chemical Fertility




      Low and Acid




      High and Neutral




      High and Alkaline

    5. Time: Time is required for the above processes to take place. In general, the longer the time element, the more apt is the soil to develop a clayey subsoil.

  4. Using soil properties to classify soils
    Soil scientists use soil properties such as slope, particle size, depth, color and degree of development to name and classify soils.

    In October 1987, the Soil Conservation Service, now the Natural Resources Conservation Service (NRCS), completed mapping the state after 50 years of strenuous effort. Now each county has it own published soils booklet. (Copies may obtained either from the local office of the County Extension Service (CES) or the NRCS.)

  5. School teachers are encouraged to consult the offices of CES or NRCS for assistance in preparing lesson plans using the county soil survey report.

  6. Selection of Hamey Silt Loam as the official state soil for educational programs. The Hamey silt loam was selected as the state soil because:

    1. It has ideal properties of a prairie soil, of which Kansas has more acres than any other state;

    2. Its nearly 4 million acres in 26 westcentral counties is the most of any of the state's more than 300 different soils;

    3. Its uneroded profile is an ideal model to which other soils may be compared;

    4. Its high crop-yield record has contributed to the state's economic wealth; and

    5. Its excellent properties make it an ideal soil to commemorate the completion in October 1987 of the State's soil inventory by more than 75 soil scientists of the SCS and the Kansas Agricultural Experiment Station.