Let

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Lets Get Down and Dirty!

• I

APES
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Soil is a mixture of eroded rock, mineral
nutrients, decaying organic matter, water, air,
and living organisms
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Mature soils are arranged in a series of zones
called soil horizons Most mature soils have at
least three of the possible horizons
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In forests you will find the O Horizon (surface
litter layer)
Topsoil layer (humus)
Subsoil layer (inorganic matter)
Parent material (inorganic matter)
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The A and O Horizons is where the interaction
with bacteria, fungi, earthworms, and small worms
take place
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Fertile soil that produces high crop yields has a
thick topsoil layer with lots of humus
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Dark brown or black topsoil is nitrogen rich and
high in organic matter
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Gray, bright yellow, or red topsoil is low in
organic matter and needs Nitrogen enrichment
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It can take 200 to 1000 years to develop an inch
of topsoil
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Soil Problems

• Acidic soil decrease uptake of nutrients
• add lime and organic fertilizer
• Alkaline soil -western and southwestern United
  States
• Add sulfur converted by bacteria to sulfuric
  acid
• Soil erosion
• Sheet erosion
• Rill erosion
• Gully erosion

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Soil removed in uniform layer slowest moving
water at top of hill
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Flowing water coalesces into small channels tiny
gullies form
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Gully Erosion
Channels coalesce into larger channels water
increases velocity and volume erodes into larger
gully
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Harmful Effects of Soil Erosion

• Loss of soil fertility
• Loss of ability to hold water
• Pollutes water, kills fish and shellfish
• Clogs irrigation ditches, boat channels
• Fills lakes and reservoirs with silt

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Providence Canyon resulted from poor farming
practices Lumpkin, GA
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Global Soil Erosion

• Topsoil is eroding faster than it forms on about
  one third of the worlds croplands
• 15 of land scattered across the globe are too
  eroded to grow crops because
• Overgrazing (35)
• Deforestation (30)
• Unsustainable farming (28)

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Global Soil Erosion

• About 40 of worlds land used for agriculture is
  seriously degraded by
• Erosion
• Salinization
• Waterlogging
• Soil degradation has reduced food production on
  about 16 of worlds cropland

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Practices That Leave Soil Vulnerable to
Desertification

• Overgrazing on fragile arid and semi-arid land
• Deforestation without reforestation
• Surface mining without reclamation
• Irrigation techniques that lead to increase
  erosion
• Salt buildup from irrigation
• Farming on land with unsuitable terrain or soils
• Soil compaction by farm machinery and cattle

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Symptoms of Desertification

• Loss of native habitat
• Increased erosion
• Salinization
• Lowering of water table
• Reduced surface water supply

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Consequences of Desertification

• Worsening drought
• Famine
• Declining health standards
• Environmental refugees

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Soil Conservation

• Conservation tillage farming (no till)
• Terracing
• Contour farming
• Strip cropping

• Alley cropping
• Gully reclamation
• Windbreaks or shelterbreaks
• Land classification

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No till farming or Minimum tillage farming
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Terrace Farming
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Strip Cropping a row of crop such as corn
alternates in strips with another crop, such as
grass-legume mixture, that completely covers the
soil
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Alley cropping or agroforestry several crops
are planted together in strip or alleys between
shrubs and trees
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Windbreaks or shelterbreaks reduce wind erosion
(retain soil moisture, fuelwood, and provide a
habitat
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Gully Reclamation
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Land Classification Identify land that should not
be cleared of vegetation or planted in crops
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Restoring Soil Fertility Organic Fertilizers
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Restoring Soil Fertility Commercial Inorganic
Fertilizer
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Green Manure plowing into soil plants currently
growing
Composting
Restoring Soil Fertility
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Restoring Soil Fertility Crop Rotation plant
areas or strips with nutrient-depleting crops
(tobacco, corn, and cotton deplete soil of
nitrogen) one year and the next year they plant
the same areas with legumes
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Not crop rotation center pivot irrigation
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Questions?