Soils Soils How much soil is there? Pretend that this apple is the - PowerPoint PPT Presentation

Soils

Soils How much soil is there? Pretend that this apple is the planet Earth, round, beautiful, and full of good things. Notice its skin, hugging and protecting the surface.Water covers approximately 75% of the surface. Right away, cut the apple in quarters. Toss three quarters (75%) away.

Soils How much soil is there? The three quarters (75%) you just removed represents how much of the earth is covered with water - oceans, lakes, rivers, streams. What is left (25%) represents the dry land. 50% of that dry land is desert, polar, or mountainous regions where it is too hot, too cold or too high to be productive. So cut that dry land quarter in half and toss one piece away.

Soils How much soil is there? When 50% is removed, this is what is left. (12.5% of the original) Of that 12.5%, 40% is severely limited by terrain, fertility or excessive rainfall. It is too rocky, steep, shallow, poor or too wet to support food production. Cut that 40% portion away.

Soils How much soil is there? You are left with approximately 10% of the apple. Peel the skin from the tiny remaining sliver.

Soils How much soil is there? The remaining 10% (approximately)- this small fragment of the land area - represents the soil we depend on for the world's food supply. This fragment competes with all other needs - housing, cities, schools, hospitals, shopping centers, land fills, etc., etc. And, sometimes, it doesn't win.

Soils A. Define soil: product of nature having both depth and surface area, resulting from both DESTRUCTIVE and SYNTHETIC forces. Weathering & microbial decay of organic matter are examples of DESTRUCTIVE forces, while the formation of NEW minerals & the development of different layers are synthetic forces at work.

Soils 5 tons of topsoil spread over an acre is only as thick as a dime.  5 – 10 tons of animal life can live in an acre of soil.  Natural processes can take 500 years to form 1 inch of topsoil. 

Soils

Soils: B. Types of Weathering 1. Physical Weathering

Soils: B. Types of Weathering 2. Chemical Weathering  CO 2 + H 2 O = Carbonic Acid  This mild acid etches the surface of rock gradually weathering it away.

Soils: B. Types of Weathering 3. Biological Weathering Roots

Soils: B. Types of Weathering 3. Biological Weathering Lichens

Soils: C. Erosion "The threat of nuclear weapons and man's ability to destroy the environment are really alarming. And yet there are other almost imperceptible changes - I am thinking of the exhaustion of our natural resources, and especially of soil erosion - and these are perhaps more dangerous still, because once we begin to feel their repercussions it will be too late." (p144 of The Dalai Lama's Little Book of Inner Peace: 2002, Element Books, London)

Soils: C. Erosion 1. Water The rain drop on impact with the soil throws small particles into the air. Flowing water then picks these soil particles up and carries them away.

Soils: C. Erosion 1. Water An unprotected crop field severely eroded after a rain storm. Much of the good top soil has washed to the bottom of the field. Other amounts have washed down into an adjacent stream.

Soils: C. Erosion 2. Wind With wind erosion, dry soil particles are dislodged by other blowing soil particles. The 1930's photo depicts a town soon to be enveloped by a giant dust storm.

Soils: C. Erosion 2. Wind With wind erosion, dry soil particles are dislodged by other blowing soil particles. The 1930's photo depicts a town soon to be enveloped by a giant dust storm.

Soils: C. Erosion 3. Ice Large rock being moved by an Alpine glacier. The figure on the right is almost 6 feet tall

Soils: C. Erosion 3. Ice

Soils: C. Erosion 3. Ice

Soils: D. Soil Components by Volume 1. Mineral: 44% - 49% 2. Organic: 1% - 6% 3. Soil Water: 25% 4. Soil Air: 25% 50 50 ___% pore ___ % solid

Soils: E. Classification by Particle Size Relative Size Comparison of Soil Particles

Soils: E. Classification by Particle Size Relative Size Comparison of Soil Particles Barrel Plate Coin Clay Silt (feels sticky) (feels floury) (< 0.002 mm, USDA) (0.05 - 0.002 mm, USDA) (< 0.002 mm, ISSS) (0.02 - 0.002 mm, ISSS) Sand (feels gritty) (2.00 - 0.05 mm, USDA) (2.00 - 0.02 mm, ISSS)

Soils: E. Classification by Particle Size Soil Components How Soil Particle Size and Surface Area Affect water holding capacity.

Soils: E. Classification by Particle Size

Soils: F. Physical Nature of Soil Separates Physical Nature of soil separates. H 2 O Holding Component Aeration Fertility Capacity Excellent None Low Sand Low Good None Silt Clay High Poor High

Soils: G. Soil Texture Define: The percentage of sand, silt and clay that a soil consists of. H. Define Loam Soil: Approximately equal amounts of sand, silt and clay.

Soils

Soils: I. Soil Solution Define: The liquid phase of soil & the dissolved solutes that are in it. J. Soil Air: The gaseous phase of soil. The relative mixtures of O 2 , N 2 , and CO 2

Soils: K. Soil pH 1. Define pH: degree of acidity or alkalinity. 7.0 Increased alkalinity Increased acidity (Low H+ concentrations) (High H+ concentrations) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Attained only by alkali Range of pH for Extreme pH for Range of pH mineral soils soils common in acid peat soils for soils (Utah Salt Flats, Humid regions (as in Peat Bog) common in Nevada) (typical Midwest Arid regions & East Coast) (S.W. Deserts)

Soils: K. Soil pH 2. pH Scale

Soils: K. Soil pH 3. Humus The dark residue remaining after the complete decomposition of organic matter.

Soils: K. Soil pH 4. Why is soil pH so important? a. Soil pH & nutrient uptake Na + Mg + Ion Ion Cations from Clay or Humus Roots pickup exchange exchange K + Ca + particles exchange Particle cations from soil (-) with cations in soil solution. solution. + Fe + NH 3 •Nutrient uptake and microbial activity depends on soil pH.

Soils: K. Soil pH 4. pH Scale b. What is the ideal pH for microbial activity and nutrient availability and uptake?

Soils: K. Soil pH Plant adaptation to acid soil

Soils: II. Soil Problems A. Acid Soils 1. Define: excessive amts. Of hydrogen ions [H+] that interfere with normal plant growth & development. 2. Amendments used to cure acid condition. To Raise Soil One Unit of pH Hydrated Ground Dolomite Lime Limestone Light Soil 11/2 2 1/2 2 pounds 100 sq. ft pounds pounds Limestone Heavy Soil 3 1/2 5 1/2 6 pounds 100 sq. ft. pounds pounds CaCO 3 + H + CO 2 + H 2 O + Ca ++ CaCO 3 ● MgCO 3 + H + CO 2 + H 2 O + Ca ++ + Mg ++ (Dolomite)

Soils: II. Soil Problems B. Saline soil 1. Define: contains excessive amts. of water soluble salts that interfere with normal plant growth & development. 2. Sources of salt: a. Evaporation of water. b. Geological deposits of salt . 3. Remedies for saline soils: a. Use higher quality water. b. Deep water (flush). c. Deep plow. d. Grow salt tolerant crops; like alfalfa & cotton.

Soils: II. Soil Problems C. Alkali soils 1. Define: Excessive amounts of Na (sodium) that interfere with plant growth and development. To Lower Soil One Unit of pH 2. Remedies for alkali soil: a. Soil sulfur Soil Ammonium Iron or Sulfur Sulphate Sulphate b. Gypsum (CaSO 4 ) Light Soil 1/2 2 1/2 3 100 sq. ft pounds pounds pounds Heavy Soil 2 6 1/2 7 1/2 100 sq. ft. pounds pounds pounds Soil sulfur.

Soils: II Soil Problems D. Caliche or hardpan 1. Limestone fused with gravel and rock by evaporation of water. 2. Characteristic of soils south of the Mogollon Rim. 3. Impenetrable to roots.

Soils: III. Cryptobiotic Soil A. What is cryptobiotic soil? 1. Means “hidden life”. 2. Crust on the surface of the soil that consists of numerous microbe species. Scabby crust common in the Sonoran Desert.

Soils: III. Cryptobiotic Soil B. Importance of cryptobiotic soil. 1. Increases fertility. 2. Slows runoff of rain (increases soil moisture and stabilizes the soil. 3. Protects against erosion. 4. Affects abundance, diversity, and health of plant species.

Soils: III. Cryptobiotic Soil C. How are human’s activities negatively affecting cryptobiotic crusts? 1. People, cattle, and vehicles crush the crust. 2. Squashed crust produces less nitrogen and carbon.

Soils: III. Cryptobiotic Soil D. How can we manage cryptobiotic soil? 1. Drive only on developed roads & jeep trails. 2. Hike on established trails. 3. Camp in a minimized zone of impact.

Soils: III. Cryptobiotic Soil

Soils: IV. Compost Making A. Compost Pile

Soils: IV. Compost Making B. Worm Composting