Presentation on theme: "Soil Chapter 12 Section 1. What is Soil? Renewable resource that can be replaced over LONG periods of time. 100’s or 1,000’s of years for just 1 inch."— Presentation transcript:
Soil Chapter 12 Section 1
What is Soil? Renewable resource that can be replaced over LONG periods of time. 100’s or 1,000’s of years for just 1 inch of topsoil to form. Mix of biotic and abiotic components Topsoil is made up of living organisms, rock particles, water, air, and dead or decomposing organisms. Quality depends upon composition
Soil as an ecosystem Soil consists of mineral and organic matter, air, and water –Dead and living microorganisms –Decaying material –Bacteria, algae –Habitat for earthworms, insects, mammals, reptiles, and amphibians Since soil is composed of interacting living and nonliving matter, it is considered an ecosystem
Soil Formation Factors FactorEffects ClimateSoil forms faster in warm, wet climates. OrganismsEarthworms and other burrowing animals mix and aerate soil, add organic matter, and affect the composition of the soil. Land-formsHills and valleys affect exposure to sun, wind, and water. Parent Material Chemical and physical characteristics of parent material influence what type of soil will be formed. TimeSoil formation takes decades, centuries, or millennia
Weathering: can be physical or chemical method of breaking down rocks and minerals. Deposition: dropping off of eroded material in a new location Decomposition: breaking down of organic material Soil Formation
Soil Components Soil is made up of 45% mineral matter, 5% organic matter, and 50% water and air. Parent material can be lava or volcanic ash, rock or sediment deposited by glaciers, sand dunes, sediment deposited by rivers, or bedrock.
Soil Horizons make Soil Profiles Soil is sorted into 6 distinct layers called soil horizons. O = Top of the ground. A = Topsoil: where most plant nutrients are found. E = minerals leach from here down into the B layer. B = subsoil C= weathered parent material. R= Parent material
Soil Characteristics The soil horizons that we just looked at are what makes up a “typical” sample of soil. U.S. soil scientists classify soils into 12 major groups based on how the soil is formed.
Color: dark soil = nutrient richness, light soil does not. Texture: texture is based upon particle size. -Clay particles are tiny -Silt particles are medium -Sand particles are large Structure: Arrangement of soil particles. Too clumpy, soft, or hard can be bad! pH: Needs to be in the neutral range –too acidic or too alkaline (basic) can create poor growing conditions. Soil Characteristics
Soil Texture Test by Feel Video
Deep Thinking 1. How does soil structure relate to flooding?