Soil properties

• Clay


  The smallest soil particle
• Sand


  The largest soil particle
• Silt


  An intermediate sized soil particle
• Structure


  The way individual soil particles are grouped together
• Texture


  A physical property of the soil referring to the relative percentages of sand, silt, and clay
• Topsoil


  The upper part of the soil profile that is normally cultivated
• Subsoil


  The area in the soil profile below the topsoil which accumulates clay
• Subsoiling


  A method of breaking up the compacted layers of the soil that restrict air and water movement and root growth using farm machinery
• Tillage pan


  Areas of compacted soil in the plant root zone created by repeated plowing of heavy soils especially when wet; also called a plow pan
• Mottling


  Spots of color in the soil that indicates internal drainage and aeration
• Texture


  • Physical property of soil considered rather permanent
  • Refers to the relative percentages of sand, silt, and clay
• Determining Soil Texture


  1. Sensing the feel

  2. Mechanical analysis
• Textural Triangle


  Used to obtain a soil textural name for a sample after it has been mechanically analyzed
• Light Soils


  Sandy or coarse texture
• Heavy Soils


  Clay or fine texture
• Loamy Soils


  Medium textured
• More desirable characteristics usually associated with highly productive soils that are easier to manage
• Differences between light and heavy soils


  • Light soils require less energy to cultivate
  • Light soils heat and cool faster
  • Light soils are usually lighter in color
  • Light soils wet and dry faster
  • Light soils are usually subject to greater erosion
  • Light soils are usually lower in fertility
• Platy structure


  Thin horizontal sheets overlapping each other
• Prismatic structure


  Long vertical columns without rounded tops
• Block-like structure


  Irregular shaped cubes
• Spheroidal structure


  Rounded and often referred to as granular or crumb; usually found in the topsoil
• Single grained soils


  Structureless soils like sand
• Solid massive condition


  Structureless soils with no noticeable peds
• Poorly drained soils


  Grey with some red or yellow streaks
• Moderately drained soils


  Yellowish-brown or reddish brown with some grey mottling
• Well drained soils


  Uniform bright color with few or no grey streaks or mottling
• Infiltration


  The movement of water into the soil
• Percolation


  The movement of water through the soil
• No-till planting


  The planting of a crop into the previous crop stubble or a cover crop, disturbing only the immediate seed zone
• Reduced-tillage


  The elimination of one or more operational procedures from a conventional system of working the soil
• Permeability


  The characteristics of a soil which permits variations in the speed of air and water movement
• Soil types and suitable crops


  • Light textured soil - oats, peanuts, beets
  • Loamy textured soil - majority of Louisiana crops
  • Heavy textured soil - flooded rice, sugarcane
• Peds


  Naturally formed groups of soil particles
• Clods


  Artificially formed groups of soil particles
• Structured soil


  • Easier to cultivate
  • Allows more water intake
  • Does not restrict root growth
  • Encourages better drainage within pore spaces
  • Allows entry of oxygen into the pore spaces after the water has drained
  • Facilitates organic matter decomposition and the release of plant nutrients
• Ways soil structure can be destroyed


  • Working the soil when it is wet
  • Repeated movement of equipment or livestock
  • Repeated use of equipment at the same depth in the soil
  • Continual flooding of the soil
• Ways to improve soil structure


  • Leaving it alone, in time it will repair itself
  • Planting a green manure crop
  • Incorporating plant residue into the soil
• Rapid infiltration and percolation rates


  Spheroidal structure and single grained structure less soils
• Moderate infiltration and percolation rates


  Blocky and prismatic structure