Soils Flashcards
What is the definition of soil?
a dynamic natural body composed of mineral and organic solids, gases, liquids and living organisms which can serve as a medium for plant growth
What are the 4 soil forming processes?
additions - to the surface
losses - from the surface or to deeper in the profile
translocations - movement within the profile, but not away from the location
transformations - weathering (chemical change)
What are the soil forming factors?
parent materials climate biota topography time
What are parent materials?
organic, mineral or a combo formed in place or transported by water, wind, ice or gravity
How does climate effect soil formation?
soil development tends to increase when soil moisture and soil temperature increase
How does topography effect soil formation?
landscape position influences susceptibility to erosion, particle decomposition, and microclimate (slope vulnerability)
What role to biota play in soil formation?
deposition of organic matter, mining of nutrients, decomposition of organic materials by heterotrophs
What are the general soil horizons?
O - organic matter A - mix of organic and mineral soil E - zone leached of clays B - accumulation of clays C - undifferentiated parent material (weathered) R - bedrock
What is the soil profile?
all the horizons in an area
What are the 12 soil orders?
alfisols, andisols, aridisols, entisols, gelisols, histosols, inceptisols, mollisols, oxisols, spodisols, ultisols, vertisols
What are alfisols?
moderately leached, lower elevations, good for agriculture
What are andisols?
volcanic ash, can be fertile, but constrained by mineral content
What are aridisols?
long dry periods, hard to see horizons, minimal O layer
What are entisols?
no horizon development, can be very young and turbulent, may or may not be good for ag
ex) sand dunes
What are gelisols?
cold, permafrost within 2 meters
What are histosols?
muck, almost entirely organic, usually wetlands
can be drained for ag, but often have micronutrient deficiencies
What are inceptisols?
weak horizon development, young or cool soils, often higher elevations, not the best for ag, but are frequently used
What are mollisols?
grassland soils, organic rich surface, very rich ag soils
What are oxisols?
intensely weathered, tend to be nutrient poor, tropics
What are spodosols?
sandy acid forest soils, distinct E layer, not great for ag