Deck 3 Flashcards
What does soil texture refer to?
mineral particles smaller than 2 millimeters (mm)
What can the texture of the soil indicate?
- The relative water-holding capacity
- Mineralogy
- Susceptibility to being transported by wind or water
- Chemical properties
What is each grouping of particle size called
soil seperate
How many major soil seperates are there?
12
How are soil colors classified?
achromatic and chromatic. The achromatic colors are white, all shades of gray, and black. They have a neutral hue and a zero chroma, but differ in value. All other colors are chromatic and represent various combinations of hue, value,and chroma.
Porosity
the amount and size of spaces between soil or rock particles
Permeability
the rate of water and air movement through soil or
bedrock, if present
Permeability is measured in ___
in/hr
List some speeds of permeability
Very slow less than 0.06 in/hr Slow 0.06–0.20 in/hr Moderately slow 0.20–0.6 in/hr Moderate 0.6–2.0 in/hr Moderately rapid 2.0–6.0 in/hr Rapid 6.0–20 in/hr Very rapid more than 20 in/hr
Healthy topsoil contains approximately how much pore space
50%
Soil compaction
Where soil pores are destroyed by tillage, intense agricultural operations, or heavy vehicle and foot traffic.
What are macropores and why are they important
The largest pores (macropores) are the most
vulnerable to compaction. The macropores are essential to the movement of gases and
water. Loss of macropores inhibits the movement of gases, including oxygen, into and
out of the soil. Plant roots and many types of microorganisms cannot grow where
oxygen is limited.
What are micropores and why are they important
The small pores (micropores) are important in holding and retaining water in the soil.
The loss of these pores lowers the permeability of the soil, thereby restricting
percolation and increasing runoff, erosion, and flooding.
