Chapter 15 Soil Resources

What is Soil? Composed of: mineral matter organic matter Modified by: weather water organisms

What is Soil? How Soils are Formed From parent material Formation time varies (200 – 1000 years) Depth varies (thin film to 10 ft)

What is Soil? Soil Composition

What is Soil? Soil Composition Other components: Humus

What is Soil? Soil Composition Other components: Pore space (wet soil) Pore space (dry soil)

What is Soil? Soil Horizons

What is Soil? Soil Organisms

What is Soil? Nutrient Cycling

What is Soil? Nutrient Cycling Elements in organic matter in animals Elements incorporated into organic matter in plants Organic matter in soil Decomposition Minerals freed and available to plant Plant roots absorb minerals from soil

Soil Properties and Major Soil Types Soil Texture: Sand, Silt, and Clay

Soil Properties and Major Soil Types Availability of nutrient minerals in clay

Soil Properties and Major Soil Types Soil Properties Affected by Soil Texture

Soil Properties and Major Soil Types pH scale Soil Acidity Pygmy Forest Most soils (pH = 4-8) 7 Death Valley 14

Soil Properties and Major Soil Types Major Soil Groups

Soil Properties and Major Soil Types Major Soil Groups

Soil Properties and Major Soil Types Major Soil Groups

Soil Problems Soil Erosion Caused by water, wind, and ice

Soil Problems Case-in-Point: The American Dust Bowl

Soil Problems Nutrient Mineral Depletion

Soil Problems Soil Problems in the United States Iowa, Missouri, Texas, & Tennessee have greatest erosion 25% of agricultural lands lose more topsoil than formed

Soil Problems World Soil Problems Mineral depletion in tropical rainforest soils Degradation in the African Sahel

Soil Conservation and Regeneration Conservation Tillage

Soil Conservation and Regeneration Crop Rotation ALFALFA 4th Year OATS 3rd Year CORN 1st Year SOYBEANS 2nd Year

Soil Conservation and Regeneration Contour Plowing, Strip Cropping, and Terracing Terracing Strip cropping & contour plowing

Soil Conservation and Regeneration Preserving Soil Fertility Organic fertilizers e.g., manure, compost + slow release, - nutrient content varies Commercial inorganic fertilizers + known nutrient content, - prone to leaching

Soil Conservation and Regeneration Soil Reclamation Shelterbelts