18 Flashcards
Pedology
Origin, classification, distribution, and description of soil.
Soil
Rock/sediment modified by physical and chemical interaction with organic material and rainwater, over time, supporting plant growth.
Natural Factors (CLORPT)
Climate
◦ Organics (biology)
◦ Relief (slope steepness) and
topography
◦ Parent material (substrate
composition)
◦ Time
The Human Factor
◦ Agricultural landscapes
◦ Nutrient loss through leaching
◦ Soil erosion
Soil Profile
Vertical section of soil; surface to
bedrock (or roots end).
Within a soil profile, soils
organized into distinct layers….
… O, A, E, B
O Horizon
Mostly organic matter leaves, soil microorganisms
Forms humus
Able to retain water and nutrients
A Horizon
Topsoil
Humus and clay particles provide essential chemical links between soil nutrients
Dark in color
Rich organic compounds
E Horizon
Light in color
Composed of coarse sand, silt, resistant minerals
Fine particles removed by eluviation
As rainfall increases, so does the rate of eluviation
B Horizon
Reddish or yellowish
Composed of accumulations of clays, aluminum, and iron by -illuviation-
Solum, true definable soil of the profile
C Horizon
The deposit at Earth’s surface
from which the soil developed
Parent material
Plant roots or soil
microogranisms are rare
R Horizon
Bedrock (e.g., granite, sandstone)
Could exist between <6 to 60 feet below topsoil
Texture
Mixture of particle size and their
proportions.
Loam
Balanced mixture good for
plants (sandy loam ideal for
agriculture b/c of its water holding characteristics).
Structure
Arrangement of soil particles
(size and shape of aggregates).
