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The Nature of Soil. Objectives. Explain how the resources soil provides help in supporting life; Explain the contents of soil; Describe the biological nature of soil; and Describe four ways plants use soil. Soil Supports Life. Soil provides many resources to life
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Objectives • Explain how the resources soil provides help in supporting life; • Explain the contents of soil; • Describe the biological nature of soil;and • Describe four ways plants use soil.
Soil Supports Life • Soil provides many resources to life • They make it possible for plants and animals to grow • We will list five of them
Soil Supports Life • Oxygen • In the soil • Needed for root growth • Temperature • Soil absorbs heat from the sun • Soil radiates heat into the atmosphere • This cycle regulates the temperature so seeds can germinateand grow
Soil Supports Life • Water • Used by growing plants • Carbon • The base of all life forms • Most essential element to life • Nutrients • Minerals that are absorbed and used by the plant
Contents of Soil • Soil is composed of four primary components • Mineral matter • Organic matter • Air • Water • In addition, there are numerous living organisms
Contents of Soil • Soil is 50/50 solid and porous • What is porous? • Solids • Mineral matter and organic matter
Contents of Soil • Solids • Mineral matter • 45%of the soil • Broken down rocks • Sand, Silt, Clay • These three things determine water holding capacity and fertility of the soil
Contents of Soil • Solids • Organic Matter • 5% of the soil • Mostly from leaves, roots and stems • Contributes to water holding capacity and fertility • Gives soil a dark color
Contents of Soil • Pore Spaces • Space occupied by air and water • Air • ≈25% of soil • Water • ≈25% of soil
Contents of Soil • Air • Constantly fluctuating • More water = less air • Less water = more air
Contents of Soil • Water • It can do two things with soil • Run off • Soak in
Contents of Soil • Terms to know • Infiltration • Water soaking into the soil • Percolation • Water moving downward through the soil • Permeable • Quality of soil when water can both infiltrate and percolate • Leaching • Movement of dissolved minerals and chemicals and salts downward with water
Contents of Soil • 3 types of soil water • Gravitational water • Water pulled down by gravity • Causes leaching • Capillary water • Water held in pore spaces • May move sideways or up • Hygroscopic water • Water that forms a thin film around soil particles • Not available to plants
Biology of Soil • What life forms would you find in the soil? • Worms • Insects • Bacteria • Fungi • Other organisms
Biology of Soil • Bacteria and fungi have an important role in the soil. • They break down organic matter and release nutrients.
Biology of Soil • Earthworms, ants, crawfish, moles, and other organisms improve the soil tilth, • Tilth: the ease at which soil can be worked. • These organisms create openings in the soil as they tunnel. • This enhances drainage and improves air exchange.
4 ways plants use soil • What are they? • Anchorage • Water • Oxygen • Nutrients