Chemistry of Soil

• a mixture of weathered rocks and minerals. decayed plants and anima material, and small living organisms which includes plants, animals and bacteria

  soil
• a typical productive soil is 5 percent organic matter and 95 percent inorganic matter
• importance of soil

  • production of food
  • maintaining balance of carbon, nitrogen and phosphorus
  • for the construction of building materials
• a layer of a typical soil is called?

  horizon
• weathering


  the horizon layer is the product of complex interactions between processes that develop during?
• top layer of soil and several inches in thickness

  horizon/topsoil
• characteristics of soil includes

  • strength
  • workability
  • soil particle size
  • permeability
  • extent of maturity
• the basic transport medium for carrying essential plant nutrients from solid soil particles into plant roots?

  water
• happens when the water in a plant evaporates into the atmosphere from the plant's leaves

  transpiration
• carries the nutrients to the plant extremities by this process wherein plants remove carbon dioxide

  soil
• the reverse of plant transpiration process

  plant respiration
• if the soil becomes saturated with water, the oxygen will immediately be consumed by the respiration of microorganisms and will cause degradation of organic matter in soil
• are produced from the weathering of parent rock and minerals

  inorganic colloids
• Inorganic colloids

  • repositories of water and plant nutrients
  • detoxifies harmful substances
  • absorbs toxic substances in soils
• what are the TWO minerals that constitute most of the mineral fraction of the soil?

  silicon and oxygen
• organic matter determines soil productivity
• a water insoluble material that biodegrades very slowly, makes up the bulk of soil organic matter

  humus
• humus is composed of a base-soluble fraction called?and an insoluble fraction called?

  humic and fulvic acids, and humin
• composed of mostly decayed plant and animal matter

  organic soils
• composed mostly of minerals

  inorganic soils
• soil humus

  • base-soluble
  • increases water-holding capacity of soil
  • binds metal
  • stabilize substances and increase sorption
• soil solution

  • aqueous portion
  • pathway for exchange of plant nutrients between roots and solid soil
• mineral and organic portions of soils both exchange?

  cations
• clay minerals undergo this process because of the presence of?

  negatively charges sites on the minerals
• if the soil is too acidic for optimum plant growth, it may restoring productivity by liming through the addition of?

  calcium carbonate
• alkaline soils may be treated with aluminum or iron sulfate which release_? during hydrolysis

  acid
• what is used to acidify alkaline soils

  sulfur
• is essentially the attachment of a chemical to either the mineral of organic portions of soil particles and include both adsorption and absorption

  sorption
• are elements that occur in substantial levels in plant biomass and fluids

  macronutrients
• Macronutrients include:

  • Carbon
  • Hydrogen
  • Oxygen
  • Nitrogen
  • Phosphorus
  • Potassium
  • Calcium
  • Magnesium
  • Sulfur
• N, P, and K are commonly added to soil as


  fertilizers
• 7 essential plant micronutrients:

  • Boron
  • Zinc
  • Manganese
  • Iron
  • Copper
  • Molybdenum
  • Chlorine
• layers of soil(top to bottom)

  1. Organic Layer-decayed matter
  2. Topsoil-minerals
  3. Eluviation Layer-leached minerals and organic matter
  4. Subsoil-deposited minerals and metal salts
  5. Parent Rock-weathered rock
  6. Bedrock-unweathered parent rock
• involved in cell division and seed formation

  boron
• essential for certain N transformation in plants

  Zinc and Manganese
• involved in chlorophyll synthesis

  Iron
• Active in redox reaction in plants

  copper
• essential for symbolic fixation of N

  Molybdenum
• Primarily involved in osmotic and cation neutralization

  Chlorine
• a common solid nitrogen fertilizer

  ammonium nitrate