Soil and Sustainable Food Production

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Soil and Sustainable Food Production
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Questions for Today

• What is Soil?
• What is Soil Erosion?
• What is desertification, salinization,
  waterlogging?
• What are ways to reduce Soil Erosion?
• How do you restore Soil Fertility?

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What is Soil?

• Soil is a relatively thin surface layer of the
  Earths crust consisting of mineral and organic
  matter that is affected by agents such as
  weather, wind, water, and organisms.
• Three components of soil
• Clay, Silt, and sand.

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Soil Horizons

• Soil is a slowly renewed resource that provides
  most of the nutrients needed for plant growth and
  also helps purify water.
• Mature soils, or soils that have developed over a
  long time are arranged in a series of horizontal
  layers called soil horizons.
• Four Horizons
• O, A, B, C

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Soil Erosion

• Producing Food has major environmental impacts.
• It can degrade
• Biodiversity
• Soil
• Water
• Air
• Human Health

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Soil Erosion

• Soil Erosion is the movement of soil components,
  especially surface litter and topsoil, from one
  place to another by the actions of wind or water.
• Soil Erosion has two harmful effects
• The Loss of Soil Fertility
• Water pollution

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Desertification

• Desertification is the loss of productivity in a
  given area due to drought and/or human
  activities.
• Occurs generally in arid or semiarid climates
• Usually due to the loss of topsoil.

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Salinization and Waterlogging

• Both Salinization and Waterlogging deal with
  irrigation of crop lands.
• When we irrigate crops, some of water absorb the
  different salts in the ground water.
• As the water evaporates, the salt is left behind
  in the topsoil.
• Over-irrigation can lead to a salinization of the
  topsoil which would render the soil sterile.

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Salinization and Waterlogging

• Irrigation can also lead to waterlogging.
• Waterlogging is, in essence, the opposite of
  salinization.
• It occurs when farmers apply large amounts of
  water to leach salts deeper into the soil away
  from the topsoil.
• If proper drainage does not exist, the saline
  water chokes out the deep roots killing the plant.

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Transpiration
Evaporation
Evaporation
Evaporation
Waterlogging
Less permeable clay layer
Salinization
Waterlogging
1. Irrigation water contains small amounts of
dissolved salts
1. Precipitation and irrigation water percolate
downward.
2. Evaporation and transpiration leave salts
behind.
2. Water table rises.
3. Salt builds up in soil.
Fig. 13-13, p. 281
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Soil Conservation

• There are many ways to prevent soil degradation
  in the world. There are four methods employed
  today
• Terracing
• Contour planting and strip cropping
• Alley Cropping
• Windbreaks

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Soil Fertility

• One of the major degradation done through
  agriculture is nutrient loss in the topsoil.
• The number one method to increase soil fertility
  is through the use of fertilizers.
• Organic Fertilizers
• Manure (Animal and Green)
• Compost
• Commercial Inorganic Fertilizers
• Fertilizers rich in nitrogen, phosphorus, and
  potassium