Chapter 16 Soil

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Chapter 16Soil

• Objectives
• Explain soil and how it is formed
• Describe five factors in soil formation
• Identify a soil profile
• Describe soil degradation
• Explain soil erosion and conservation

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Terms
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Pedology

• Pedology is the science of soils
• It includes the origin, nature, and
  classification of soil

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Soil Content
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Mineral Materials
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Sizes of Soil Particles
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Using a soil texture unit to determine the
mineral composition of soil
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Water

• Gravitational water is the water that drains
  downward through the soil
• Capillary water is the water held between the
  soil particles
• Hygroscopic water is the water that adheres to
  each soil particles

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Air

• Most plants require a balance between air and
  water in the soil

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Organic Matter

• Organic matter is made of decaying plant and
  animals remains
• Organic matter that is well decomposed is known
  as humus

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The factors in soil formation are

• Parent material is the mass of mineral and
  organic matter from which soil is formed
• Climate precipitation, temperature, wind, and
  other climates factors influence weathering
• Living organism soil processes are affected by
  all organisms that live in it-microbes,
  earthworms, insects, nematodes, spiders, rodents,
  and other animals
• Topography is the form or outline of the surface
  of the earth
• Time is important in weathering because it cannot
  be replaced or accelerated

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Wave action wears away and dissolves rock form
soil
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The examples of animals that help form soil
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How plants help make soils
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Soil Profiles

• A soil profile is a vertical section of the soil
  at a specific site

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Soil Profiles

• O horizon
• A horizon
• B horizon
• C horizon
• R horizon

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Physical Classification of Soil

• Soil texture
• Soil depth
• Soil color
• Structure
• Consistency
• Permrability

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Soil Texture

• Soil texture is the proportion of these three
  components in the soil (sand, silt, and clay)
• A soil triangle is a graphic explanation of the
  proportions of sand, silt, and clay

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Soil Depth

• Very shallow soils are usually less than 10 feet
  thick
• Shallow soils are 10 to 20 feet thick
• Medium depth soils are 20-40 feet thick
• Deep soils are more than 40 feet thick

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Soil Color

• The color often depends on the kind of parent
  material and the amount of organic matter present
  in the soil

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Soil Structure

• Soil structure is the arrangement of soil
  particles into shapes and pieces
• Soil can have eight different types of structure
• Granular
• Plate
• Subangular
• Blocky
• Prismatic
• Flat
• Single grain
• Columnar

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Consistency

• Consistency is the ease in working with a soil

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Permeability

• Permeability is the movement of water in soil
• Permeability includes infiltration and
  percolation
• Infiltration is the moving of surface water into
  the soil
• Percolation is the movement of water downward
  through the soil

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Water infiltration and percolation
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Chemical Characteristics of Soil

• Soil pH is the acidity or alkalinity of soil
• Nutrient is testing the soil to learn the kind
  and amount of selected nutrients that are present

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pH Scale
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Nutrient Analysis

• Collecting a soil sample for laboratory testing

• Testing a small sample of soil using test kit

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Essential Plant Nutrients
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Usefulness of Soil

• Agriculture
• Livestock production
• Forest area
• Habitat
• Industrialization
• Recreation

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Soil Degradation

• Construction
• Contamination
• Erosion

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Construction

• Construction is altering land by building roads,
  houses, office buildings, factories, and other
  structures

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Contamination

• Contamination results when chemicals, oil, and
  other substances get onto the land

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Erosion

• Soil erosion is the process by which soil is
  removed
• Natural erosion
• Accelerated erosion removes topsoil at an
  excessive rate

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Causes of Erosion

• Wind
• Water
• Glaciers
• Land slippage

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Wind erosion
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Water in a stream containing a high amount of
sediment
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Kinds of Erosion

• Sheet erosion results when thin layers or sheet
  of soil are worn away
• Rill erosion is usually on sloping land where
  small channels are formed in the soil by running
  water
• Gully erosion is a severe kind of erosion

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Rill Erosion
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Small Gully
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Eight land capability classes are used

• Class I land- This is the best agricultural land
• Class II land- This is good agricultural land
• Class III land- This is fair agricultural land
• Class IV land- This is poor land for tillage, but
  can be good in pastures or forests
• Class V land- This class is unfit for field crops
• Class VI land- This class has land restricted to
  use as pastures. Woodlands, or wildlife refuges
• Class VII land- This land has very limited use
• Class VIII land- This land is steep mountain
  sides, sandy beaches, and river washes that have
  little productive use

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Soil Conservation in Urban Areas

• Mulch
• Silt fences
• Cover crops
• Building on the contour
• Stabilizing banks
• Planting trees and shrubs
• Storm water management

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Soil Conservation in Agricultural Areas

• Plant on the contour
• Rotate crops
• Terraces
• Grass strips
• Diversion ditches
• Strip cropping
• Vegetative covers
• Conservation tillage
• Wind breaks

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Tests

• What is the major materials in soil?
• How is soil formed?
• What is soil profile?
• What is a soil triangle?
• What is permeability and why is it important?
• What are the two major chemical characteristics
  of soil?
• What is soil degradation?
• What are three kinds of degradation?
• What are the kinds of erosion?
• What soil conservation practices may be used?