? about soil

Discussion in 'Pesticide & Herbicide Application' started by George777, Jan 9, 2003.

  1. George777

    George777 LawnSite Senior Member
    from Alabama
    Messages: 305

    my question is this, how is hydroden, oxygen, and carbon effected in a clay soil? Most lawns in my area have Alabama clay. Some lawns you can't even get a soil probe in the ground.

    if a typical composition is 25% water, 25% air, and 45% mineral, how is this effected in a clay soil? Is the 25% air reduced to 15-10% and the water increased to 30-35%?What effect on plants will this have.
  2. SWD

    SWD LawnSite Senior Member
    Messages: 988

    George, clay is the smallest particle sized soil used in soil profile classifications.
    Because it is smaller, water adheres to each soil particle greater-thereby not allowing enough water to the plant roots.
    Clay has a higher charge than sand or silt meaning on each exchange site, clay retains more of the chemicals, both macro and micro meaning less is available to the plant roots.
    Because of these two conditions, clay is necessary in the soil profile, yet in balance with sand and silt.
  3. lawnstudent

    lawnstudent LawnSite Senior Member
    Messages: 472

    Along with nitrogen, carbon, oxygen and hydrogen are the nutrients consumed in the largest quantities (potassium in some grasses is very close in consumed quantities) by all plants.

    Clay has no direct bearing on the availability of carbon to a plant. Carbon is burned in the photosynthesis process. Carbon is aquired from the air as carbon dioxide through the leaf openings or stomata.

    Hydrogen is aquired by the plant in the form of water absorbed through its roots. High clay or high sand content will reduce the amount of water availalbe to a plant. High clay also cay restrict root development, further reducing the plants ability to collect water. Loams offer the most water to a plant.

    Oxygen is used in plant respiration (the opposite of photosynthesis). Oxygen is aquired from air at the site of plant respiration through the stomata and from water absorbed through a plant's roots. Roots can not operate without oxygen. Clay reduces the pore space of a soil and, therefore, reduces the amount of oxygen available to the roots.

    In an ideal mineral soil, 50% is pore space. This is true for a loam soil. High clay content soils reduce the overall pore space to something less than 50%. Also, clay holds water so tightly that water content may increase in the soil at the expense of air, but this water may not be available for the plant to absorb (the chemical bond between the caly particles and water are too great for the plant roots to overcome). Some plants litteraly drown in high clay soils (not enough oxygen and too much water). Hope this helps!


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