SoilsI. Importance of soilII. Soil structure
A. CompositionB. Soil formation
III. Soil typesA. Soil typesB. Soil particles:
1. Sand and silt2. Clay3. humus
IV. Soils and ecosystems
II. Soil structureA. Composition
1. Inorganic matter
Rocks and minerals Air and water
2. Organic matter
LivingDead
dynamic equilibrium
air
water50%
B. Soil formation
Big chunks into little chunks
Decomposition
Rocks and minerals:
weathering
End point:
Organic matter end point:humus
sand, silt, and clay
(recalcitrant)
horizons
III. Soil typesA. Soil typesB. Soil particles:
1. Sand and silt2. Clay3. humus
Particle Size(mm)
Shape
Feel Charge
Sand
Silt
Clay
Humus
2 – 0.2
.2 - .002
< .002varies
chunky
chunky
plates
amorphous
gritty
floury
sticky
spongy
inert
inert
ert (-)
ert (+/-)
IV. Soils and ecosystems
Acidic, organic
Deep organic
Very acidic, anaerobic
Shallow, low organic
Sandy, low organic
Loess
Palouse