Soils

1
Soils

• Chapter 5

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SOIL

• Is the soft material that covers the surface of
  the earth and provides a place for the growth of
  plant roots.
• It also contains minerals, organic matter, air,
  and water.

3
Parent Material

• Igneous rocks heat created from deep in the
  earth. Granite, quartz
• Sedimentary rocks formed by moving particles
  (wind water and glacial) and then recombining.
  Limestone, sandstone
• Metamorphic rocks that have changed due to high
  pressure and or high heat. Marble and slate

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Formation of Soil(weathering)

• Water
• Movement
• Freezing
• Wind
• Glacial
• Chemical
• Temperature
• Mechanical
• Roots, earthquakes, landslides

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Five factors control soil formation

• Parent material
• Time
• Climate
• Vegetation
• Topography

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Composition of soil.
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Soil Textures

• is the amount of sand, silt and clay in the soil.
• Clay fine and plat like, holds a tremendous
  amount of water and nutrients poor drainage.
  Smallest
• Silt in between particle between clay and
  sand. Medium.
• Sand excellent drainage, warms up quickly in
  the Spring, poor water retention and fertility.
  Largest.

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Texture Triangle
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Soil Profile

• Refers to the arrangement and properties of the
  various soil layers.
• Top soil
• Sub soil
• Parent Material

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Soil Horizons

• O Horizon
• A Horizon
• B Horizon
• C Horizon
• Depth Colors

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Soil Water Relationship

• Why is water needed in the soil?
• Movement of minerals into the plant
• Movement of glucose
• Photosynthesis
• Cooling
• Water types
• Gravitational water
• Capillary water
• Hygroscopic water
• Crystal lattice water

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Soil Water Relationship cont.

• 1) Hygroscopic Water is held so strongly by the
  soil particles (adhesion), that it is not
  available to the plants
• 2) Capillary Water is held by cohesive forces
  greater than gravity and is available to plants
• 3) Gravitational Water is that water which cannot
  be held against gravity
• as water is pulled down through the soil,
  nutrients are "leached" out of the soil
  (nitrogen)

13
Saturation Percentage

• Immediately following an irrigation, the film of
  water is thick, and smaller pores are full of
  water. The soil particles can not hold the
  water. It is easily lost to the plant.
• 1/10 Atmosphere (Near Saturation)

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What is Field Capacity?

• when the soil contains the maximum amount of
  available water, the greatest amount of water it
  can hold against gravity.
• 1/3 Atmosphere
• ½ saturation

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What is Permanent Wilting Point?

• the soil has so little water, that plants can no
  longer recover from wilting.
• roots can no longer take in water.
• 15 Atmospheres.
• ¼ Saturation

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What is Available Water?

• the amount of water between field capacity and
  wilting point

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Chemical Properties

• Soil pH
• The amount of hydrogen ions in the soil.
• Soil pH range is 0 to 14.
• Acid soil is soil with a pH below a 7
• -Probably high rainfall and possibly high
• in organic matter.
• -Use lime to raise pH
• -Many fertilizers have an acid affect on
• the soil.

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pH cont.

• Alkaline soil is that which is above a pH of 7
• -Low rainfall areas
• -Use sulfur to lower pH
• Neutral at a pH of 7
• -Gypsum acts a buffering agent

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Cation Exchange Capacity

• Used to determine fertilization schedules

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• Sodic and Saline Soils High amounts of sodium
  with a pH of 8.5 or above.
• Saline-sodic Soils same as Sodic but with a pH
  of 8.4 or below.

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Organic Matter

• Improves physical condition structure.
• Increase water infiltration.
• Decrease erosion losses.
• Supply plant nutrients.
• Micro-Organisms enrich the soil.

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Soil Classification

• Why classify soil?
• How can it help you?

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Soil Management

• Erosion
• Sheet Rill
• Gully
• Conservation
• Contour Cropping
• Strip cropping
• Terraces
• Grass Waterways
• Conservation Tillage
• No-Till
• Minimal Till
• Ridge Planting System

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Soil Compaction

• What is soil compaction?

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Soil Compaction

• How do we prevent soil compaction?
• How do we repair soil that is compacted?