Soil Resources Chapter 7 Bill Nye Rocks and Soils

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 Humus

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

What is Soil? Soil Horizons

What is Soil? Nutrient Cycling

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

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

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

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

Soil Problems Nutrient Mineral Depletion

Soil Problems Soil Problems in the United States Cultivated soils in southern Iowa, northern Missouri, western and southern Texas, & eastern 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 Contour Plowing, Strip Cropping, and Terracing Strip cropping & contour plowing Terracing

Soil Conservation and Regeneration Preserving Soil Fertility Organic fertilizers e.g., manure, compost slow release, but nutrient content varies Commercial inorganic fertilizers e.g., typical bagged fertilizer exact nutrient content known, but prone to leaching

Soil Conservation and Regeneration Soil Reclamation increasing productivity on eroded land Shelterbelts

Soil Video Clip m/soil/preview.weml