where does soil come from? rocks minerals organic matter

Where does soil come from?

•Rocks•Minerals

•Organic Matter

Soil Properties

• Color – depends on organic matter and chemicals

• Texture – mixture of sizes of particles• Structure – arrangement of soil particles• Consistency – combo of texture and

structure• Porosity – loose or tightly packed

together?• Moisture – percentage of water content• Chemistry – N, O, CO2

Soil Horizons

• Run parallel to the earth’s surface and has characteristics different from horizons directly above or below.

oA

E

B

C

R

TOP SOIL

SUBSOIL

• O – “Organic” (plant & animal matter); dark in color; retains water and nutrients

• A – organic & clay; dark in color• E – “Eluviation” (minerals removed by

water seepage); coarse sand & silt; light in color

• B – clay; aluminum & iron; red/yellow from deposited minerals

• C – weathered bedrock• R – “Rock,” many different colors; no

nutrients

Sagebrush-Cold Desert

What are the main components of soil?

• Mineral Matter• Air

• Water• Organic Matter

SOIL COMPONENTSidealized soil

SOIL SOLIDS

WATER FILLED PORES

AIR FILLED PORES

50 %

25 %

25%

Soil Components (volume basis)

Note: clays are microscopic in size !

Soil separate particle diameter (mm)____________________________

Sand . . . . . . . . . 2.0 - 0.05

Silt . . . . . . . . . . 0.05 - 0.002

Clay . . . . . . . . . . <0.002

SAND

SILT CLAY

Clay mineralsphotographedwith an electronMicroscope.

Note: they are plateor flake like andare stacked on topof each other.

They are electricallycharged and act likemagnets that attractand hold plantnutrients.

What causes soil erosion?

WaterWind

No Vegetation

How did the Canyon Lands of Utah form?

What are some practices

Of

SOIL CONSERVATION?

TerracingStrip Cropping

Contour PlowingTilling

Wind BreaksGround Covers

What are the FACTORSthat make SOIL?

TIME1000’S TO 10,000’S OF YEARS

LAY OF THE LANDTOPOGRAPHY

LIVING ORGANISMSANIMALS AND PLANTS

CLIMATEHOT/COLD, WIND/RAIN

PARENT MATERIALROCKS AND MINERALS

Physical land features