"A cloak of loose, soft material, held to the earth's hard surface bygravity, is all that lies between life and lifelessness. Crumbling rock,grit and grime, and decaying residue - abrading by wind and water – weather into soil - Mother Earth. This loose hide lives - yields, yet does not yield to the forces of climate, having formed through the ages from meteorological, geological and biological action on rock. The soil not only was born out of fire, flood and ice but it lives and continues to renew life. At first, animal and plant residues decayed into simpler constituents, renewing nutrient elements available for new life in a perpetual cycle, but now, wastes accumulating from the population bulge of human beings adds seriousproportions to the burden of cycling and recycling."

Wallace H. Fuller, in Soils of the Desert Southwest ,

University of Arizona Press, 1975.

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What is Soil? Why is it important? What is it made of? What are its important

characteristics? What is a soil profile? What different types of

soil are there, what makes them different, and how are they distributed?

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Living Membrane of the planet!

Basic Recipe for Soil

Minerals (from weathered rocks) Air Water Organic material (plant and animal residue) Organisms (Lots!)

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Types of Weathering Chemical

Acids in water break down minerals in rocks

Most intensive in tropical areas

Physical Mechanisms: Wind, Glaciers,

Freeze/Thaw Most intensive in mountainous

areas

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Water expands whenit freezes

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More room for air whenparticles of varied sizes!

Soil Ecosystems

Thous-ands of organ-isms in every handful!

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How would you describeSoil?

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Fig. 10.2

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CS Fig. 10.3

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Good for drainage

Good for creatingpore space

Good for moistureretention

BestForCrops!

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Movement ofmaterial

with time

http://courses.soil.ncsu.edu/resources/soil_classification_genesis/soil_formation/soil_transform.swf

A real soil profile: Dark, rich soil in A Pale leached appearance in

E Orange color from iron in B Lots of chunks of rock in C Solid rock in R

Fig. 10.6

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Slow:(Many10,000’sof years)

Fast:(1000’s to 10,000’s of years)

Comparison of Soil Types

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Minnesota Farmland

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Minnesota Soil

(Lester Series)

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LESTER SERIESThe Lester series consists of very deep, well drained soils that formed in calcareous loamy glacial till on till plains and moraines. These soils have moderatepermeability. Their slopes range from 5 to 70 percent. Mean annual precipitation is about 28 inches. Mean annual temperature is about 47 degrees F.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Mollic Hapludalfs

Ap--0 to 7 inches; very dark grayish brown loam, grayish brown (10YR 5/2) dry; moderate fine subangular blocky structure; friable; many fine roots;about 3 percent gravel; slightly acid; abrupt smooth boundary. (6 to 10 inches thick)

Bt1--7 to 21 inches; brown clay loam; moderate medium subangular blocky structure; firm; many very fine roots; about 2 percent gravel; slightly acid; clear smooth boundary.Bt2--21 to 38 inches; dark yellowish brown clay loam; moderate medium subangular blocky structure; friable; common fine roots; about 3 percent gravel; slightly acid; gradual smooth boundary. (Combined Bt horizon is 10 to 40 inches.)

http://www.statlab.iastate.edu/soils/photogal/statesoils/list1.htm

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Bk1--38 to 50 inches; yellowish brown loam; weak medium subangular blocky structure; friable; few fine roots; common very pale brown carbonate threads; about 2 percent gravel; violently effervescent; slightly alkaline; clear wavy boundary.

Bk2--50 to 60 inches; yellowish brown loam; weak medium subangular blocky structure; friable; common fine distinct yellowish brownrelict Fe concentrations; common very pale brown carbonate threads; about 2 percent gravel; violently effervescent; slightly alkaline; clear wavy boundary.

C--60 to 80 inches; yellowish brown loam; ; massive; friable; common medium distinct yellowish brown relict Fe concentrations; about 1 percent gravel; strongly effervescent; slightly alkaline.

TYPE LOCATION: Wright County, Minnesota; about 3 miles west of Otsego, 1460 feet south and 200 feet west of the northeast corner of Sec. 15, T.121 N.,R.24 W.; USGS Big Lake quadrangle; lat. 45 degrees 17 minutes 29 seconds N.; long. 93 degrees 41 minutes 3 seconds W., NAD27

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The End.

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