Soil Horizons
It’s the very top layer of soil. Made mostly of organic material
O Horizon- Organic matter
earth moving, overuse, compaction is known as
Human Activity
Indicate certain physical and chemical characteristics. Due primarily of two factors:
Humus and Iron compounds present
Soil Color
sand, silt, clay
Mineral particles
particles are the largest, ranging from 0.05 to 2.0 millimeters in diameter.
Sand
Beneath all other soil layers – the bottom of the soil profile. Contents unweathered bedrock such as sandstone, granite, or limestone.
R Horizon -Bedrock
Plants, animals, insects and microbes affect soil formation
Biological Activity
Size, shape, and arrangement of soil particles and associated pores determine the ability of the soil to retain water
Water Holding Capacity
moisture that supports plant and microbial life
Water
particles are intermediate in size, falling between 0.002 and 0.05 millimeters in diameter.
Silt
Below the B Horizon; just above the bedrock. Partially weathered parent material; little to no organic matter.
C Horizon -Parent Rock
Affected by glacial ice, wind, water, gravity, volcanic deposits and organic deposits
Parent Material
Refers to the total depth of parent material or soil layers. Classified by the following:
−Deep: 35 inches or more
−Moderately deep: 20–35 inches
−Shallow: 10–20 inches
Very shallow: 10 inches or less
Soil Depth
oxygen and other gases in soil pores
Air
particles are the smallest, with diameters less than 0.002 millimeters.
Clay
Just below the O Horizon (if present). mix of minerals (sand, silt, clay) and organic matter (decayed plants and animals).
A Horizon -Top Soil
Mature soils are generally productive but become less as they continue to age
Time
Refers to weight of oven-dry soil with its natural structural arrangement (NO WATER)
Soil Density
decomposed plants and animals (humus)
Organic matter
This soil particle holds water better than sand but not as much as clay
silt
Below the E Horizon- Contains minerals like clay, iron, and aluminum that have leached down from upper layers; low in organic matter.
B Horizon- Subsoil
Soils position in a landscape influences soil development mainly be affecting water movement
Topography
Refers to the arrangement of soil particles. Classified by these 3 main types
Structureless, With-structure, Structure-destroyed
Soil Structure
microbes, insects, worms, fungi, etc.
Living organisms
used to determine the textural name of a soil by mechanical analysis
Soil texture triangle