Soil

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Soil Land ManagementAgriscience Applications

• By Johnny M. Jessup
• Agriculture Instructor/FFA Advisor

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What is Soil?

• Is the top layer of the Earths surface suitable
  for the growth of plant life.

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The Soil Profile

• Soil Horizon
• They are the layers of the different types of
  soil found at different depths in soil profile.
• Soil Profile
• A vertical section through the soil extending
  into the unweathered parent materials and
  exposing all the horizons.

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Master Horizons

• What are the Master Horizons?
• The are A, B and C horizons are known as the
  master horizons. They are a part of a system for
  naming soil horizons in which each layer is
  identified by a code O, A, E, B, C and R.

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Horizons

• The O Horizon
• The organic layer made of wholly or partially
  decayed plant material and animal debris.
• Normally found in a forest with fallen leaves,
  branches and other debris.

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Horizons

• The A Horizon
• Usually called the topsoil.
• Surface layer of soil for judging purposes.
• Usually contains more organic matter.
• Somewhat darker in color.
• Provides the best environment for the growth of
  plant roots, microorganisms and other life.

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Horizons

• The E Horizon
• This is the zone of the greatest leaching of
  clay, chemicals and organic matter.

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Horizons

• The B Horizon
• Subsurface layer of soil for judging purposes.
• Called the subsoil.
• Called the zone of accumulation where chemicals
  leached out of the A horizon.
• Reason why most subsoil has an increase in
  clay content.

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Horizons

• The C Horizon
• Called the parent material.
• Lacks the properties of the A and B horizon.
• Less touched by soil forming processes.

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Horizons

• The R Horizon-
• Is the underlying bedrock such as the limestone,
  sandstone, and or granite.

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Soil Characteristics
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Soil Texture

• Refers to the size of soil particles.
• Which are
• Sand (Large)
• Silt (Medium)
• Clay (Small)

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Relative Size of Soil Particles
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Soil Texture - Sand

• Is the largest of the soil particles.
• Individual particles can be seen with
  the naked eye.
• Sandy soils have problems holding enough water
  for good plant growth.

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Soil Texture - Sand

• Sand is also gritty to the touch.
• Sand grains will not stick to each other.
• Four types of sand grains are.
• Very coarse sand
• Coarse sand
• Medium sand
• Fine Sand

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Soil Texture - Sand
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Soil Texture - Silt

• Intermediate or medium sized soil particles.
• But cant be seen with the naked eye.
• Is the best soil as it has the ability to hold
  large amounts of water in a form plants can use.

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Soil Texture - Silt
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Soil Texture - Clay

• The smallest of soil particles.
• Clayey hold lots of water, but they.
• May be airtight.
• Infertile for root growth.
• Associated with wet soils.
• Clay will hold more plant nutrients than any
  other soil particle.
• Clay particles stick to one another.

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Soil Texture - Clay
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Textural Classes

• There are 12 textural classes.
• Represented on the Soil Texture Triangle.
• Textural class determined by the percentage of
  sand, silt, clay.

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Soil Structure

• Refers to the way soil particles cluster together
  to form soil units or aggregates, while leaving
  pore space to.
• Store air.
• Store water.
• Store nutrients.
• Allow root
  penetration.

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Types of Soil Structures

• There are five types of soil structures.
• They are
• Single grain
• Granular
• Platy
• Blocky
• Prismatic

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Soil Structure Single Grain

• Associated with sandy soils.

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Soil Structure - Granular

• Particles cling together to form rounded
  aggregates.
• Very desirable for all soil uses.
• It is commonly found in A horizons.
• Peds are small usually between 1 to 10
  millimeters

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Soil Structure - Platy

• Usually found in E horizons.
• Large, thin peds.
• Plate-like arranged in overlapping horizontal
  layers.

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Soil Structure - Blocky

• Particles cling together in angular aggregates.
• Typical of soils with high clay content.
• Typical of B horizons.
• Peds are large about 5 to 50 millimeters

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Soil Structure - Massive

• Soil has no visible structure.
• Hard to break apart appears in very large clods.

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Land Classification
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Land Capability Maps

• Based on the physical, chemical, and
  topographical aspects of the land.

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Land Capability Classes

• Assigning a number to
  land.
• Eight classes used.
• I to VIII with I having the
  best arability.
• Class I to IV can be cultivated.
• V to VIII tend to have high slope or are low
  wet.

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Land Capability Classes

• Class I - Very good land.
• Very few limitations.
• Deep soil and nearly level.
• Can be cropped every year as long as land is
  taken care of.
• Class II - Good land
• Has deep soil.
• May require moderate attention to conservation
  practices.

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Land Capability Classes

• Class III - moderately good land.
• Crops must be more carefully selected.
• Often gently sloping hills.
• Terraces and stripcropping are more often used.
• Class IV - fairly good land.
• Lowest class cultivated.
• On hills with more slope than class III.
• Class V - Unsuited for cultivation.
• Can be used for pasture crops and cattle grazing,
  hay crops or tree farming.
• Often used for wildlife or recreation areas.

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Land Capability Classes

• Class VI - Not suited for row crops.
• Too much slope.
• Usually damaged by erosion with gullies.
• Can be used for trees, wildlife habitat, and
  recreation.
• Class VII - Highly unsuited for cultivation.
• Has severe limitations.
• Best used for planting trees.
• Steeply sloping.
• Large rock surfaces and boulders may be found.
• Very little soil present.

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Class VIII

• Cannot be used for row crops or other crops.
• Often lowland covered with water.
• Soil maybe wet or high in clay.
• Best suited for wildlife recreation.

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Soil Conservation Enhancement
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Soil Erosion

• Can be stopped and/or reduced by good soil
  management.
• Management practices that reduce soil erosion
  increase water absorption and retention.

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Types of Erosion

• Sheet erosion
• Removal of layers of soil from the land
  into streams.
• Gully erosion
• Soil removal that leaves trenches.

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Soil Conservation Methods

• Reduce rain drop impact.
• Reducing/slowing the speed of the wind or water
  movement across the land.
• Securing soil with plant roots.
• Increasing absorption of water.
• Carrying run-off water safely away.

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Recommended Practices

• Cover crops
• Mulching
• Conservation tillage
• Contour practices
• Strip cropping
• Crop rotation

• Add organic matter
• Liming and fertilizer
• Grass waterways
• Terracing
• Avoid overgrazing
• Use a conservation plan

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Recommended Practices No Till

• Cropping technique used to reduce soil erosion.
• Crops are planted directly into the residue of a
  previous crop without plowing or disking
• Very effective erosion control.

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Recommended Practices Conventional Tillage

• Uses tillage system that disturbs the soil
  surface by.
• Plowing
• Disking
• Harrowing

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Recommended Practices Conservation Tillage

• Intermediate tillage system between conventional
  no-till.

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Soil Enhancement - Fertilizer

• Fertilizer
• To add nutrients to the soil.

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Soil Enhancement - Lime

• Using as an amendment to raise soil pH.
• Increases availability of nutrients.
• Example
• If soil pH is 5.5, lime may be added to raise
  soil pH to a more acceptable 7.0 level.

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pH Scale
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Careers in Soil Management
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Agencies

• Soil Water Conservation District
• Natural Resources Conservation Service
• Formerly the Soil Conservation Service
• Farm Service Agency
• Formerly the Agriculture Stabilization
  and Conservation Service
• Environmental Protection Agency

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What do these agencies do?

• Provide advice.
• Technical assistance.
• Funds to assist land owners with soil water
  conservation.
• Monitor ground water quality.
• Enforce point nonpoint pollution laws.

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Careers Needing a Bachelors Degree

• Soil Scientist
• Classify soil according to the most appropriate
  use.
• Soil Conservationist
• Assist landowners in implementing best
  land use practices.

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Careers Not Needing a Bachelors Degree

• Soil Technician
• Uses soil auger/soil tube to take soil samples
  and do field work.

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Designed By

• Johnny M. Jessup, FFA Advisor
• Hobbton High School