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

I. Importance of soil

Microorganisms

Primary producers

II. Soil structureA. Composition

1. Inorganic matter

Rocks and minerals Air and water

2. Organic matter

LivingDead

dynamic equilibrium

air

water50%

B. Soil formationFactors:

Geology,

Climate,

Organisms,

Topography,

Time

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 (+/-)

Soil Triangle

IV. Soils and ecosystems

Acidic, organic

Deep organic

Very acidic, anaerobic

Shallow, low organic

Sandy, low organic

Loess

Palouse

The end