a closer look and water and soil degradation
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A Closer Look and Water and Soil Degradation. Soil Erosion Facts. Soil is a “potentially renewable resource” – a resource that can be renewed in days to several decades, but when the resource is used faster than it is replenished it becomes a non-renewable resource.

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soil erosion facts
Soil Erosion Facts
  • Soil is a “potentially renewable resource” – a resource that can be renewed in days to several decades, but when the resource is used faster than it is replenished it becomes a non-renewable resource.
  • 1992 Study by the World Resource Institute found that:
  • 15% of global lands are too eroded to grow crops on due to overgrazing, deforestation, and unsustainable farming practices.
  • 2/3 of these lands exist in Africa and Asia.
  • 40% of the world’s lands (75% in Central America) used for agriculture are seriously degraded by erosion, salt build-up, and waterlogging.
  • Soil erosion has reduced food production on 16% of the world’s arable (crop) lands.
  • Worldwide soil erosion causes at least $375 billion per year ($42 million per hour!) in

1. direct damage to agricultural lands

2. indirect damage to waterways, infrastructure, and human health.

  • Soil erosion cost $30 billion dollars in 1997 (3.4 million per hour!)
  • Desertification causes plant productivity to fall by 10% each year (a process whereby arid and semiarid lands change to desert-like conditions due to human activities and climate changes).
agents of erosion
Agents of Erosion
  • Wind
  • Water
  • Ice
  • Gravity

(mass wasting)

types of soil erosion
Types of Soil Erosion
  • 1. Sheet Erosion – occurs when surface water flows down hill and peels off top soil in a sheet-like pattern.
  • 2. Rill Erosion – is from fast moving surface water that gouges out rivulets that cut small channels into the soil.
  • 3. Gully Erosion – when rivulets join together to make a larger gully.

Sheet erosion


Gully Erosion

causes of the dust bowl
Causes of the Dust Bowl
  • Poor cultivation practices on fertile, arable lands where plowing tore up the roots of native prairie grasses (extensive root systems) which were replaced by agricultural crops (less extensive root systems).
  • After each harvest, the land was plowed and left bare for several months, exposing it to high winds.
causes of the dust bowl1
Causes of the Dust Bowl
  • Overgrazing destroyed large expanses of grass, denuding the ground.
  • Drought – occurred between 1926 and 1934.
journalists name the dirty thirties the dust bowl
Journalists Name the “Dirty Thirties” the “Dust Bowl”
  • During May, 1934, a cloud of topsoil blown off the Great Plains (1,500 miles away) blanketed most of the eastern United States (Washington D.C. and New York City).
  • The same day, Hugh Bennett of the U.S. Department of Agriculture (USDA) was in Washington as the dust arrived pleading for new programs to protect the country’s topsoil and farmers.
did we learn our lesson from the dust bowl
Did We Learn Our Lesson From the Dust Bowl?
  • 1935 – USA passed the Soil Conservation Act which established the Soil Conservation Service (SCS), now called the Natural Resources Conservation Service (NRCS), and began promoting sound conservation practices, initially in the Great Plains States and then in each County in every state! Soil Survey’s were developed.
  • Farmers who migrated to California began using the land more sustainably and invited assistance from USDA and Soil Conservation Service. ‘No till farming” was introduced where the soil is disturbed slightly by making slits in rows in which seeds are planted.
soil protection regulations
Soil Protection Regulations
  • 1973 – Sediment Pollution Control Act – requires that no land-disturbing activity during periods of construction or improvement to land shall be permitted in proximity to a lake or natural watercourse unless a buffer zone is provided along the margin of the watercourse AND the angle for graded slopes and fills cannot be greater than the angle which natural vegetation can be established and retained for soil anchorage (slope stabilization).
  • A Sediment and Erosion Control Plan MUST be submitted and approved by the regulatory agency overseeing the project.
sediment pollution control act 1973
Sediment Pollution Control Act - 1973

Coir Fiber matting

Silt Curtain

Hay Bales



farmland preservation act
Farmland Preservation Act
  • State agencies must establish agricultural land preservation policies and working agreements with the USDA.
  • The goal is to minimize farmland conversions from agricultural zoning to residential and industrial zoning.
  • For approved conversions and Utility projects, the USDA reviews and ensures that Plans contain construction and restoration standards that leave affected areas in good condition after projects are completed.
farm act 1985
Farm Act - 1985
  • Farmers are given subsidies for highly erodible land.
  • They MUST take the land out of production for 10 years.
  • The land may NOT be farmed, grazed of cut for hay OR farmer must pay back subsidy!
  • This has cut erosion by 60% in the USA since 1985.
  • “Swampbusters” is part of the Farm Act – denies federal funding to farmers who drain or destroy wetlands on their property.
a look at hydroponic and aeroponic crop production
A Look at Hydroponic and Aeroponic Crop Production
  • Hydroponics – based on the idea that plants will grow as long as they have air, water, nutrients, and energy, but not necessarily soil.
    • Two Types:

a. Water culture – where roots of plants are in water instead of soil, air is pumped in, and nutrients are added.

b. Aggregate Culture – where plants are placed in sand, gravel, or peat which supports the plant and lets air get to the roots like soil does. Nutrients are added.


Drip Irrigation Technique

  • Aeroponics is a hydroponic technique involving the use of sprayers, nebulizers, foggers, or other devices to create a fine mist of solution to deliver nutrients to plant roots.

Root Mist Technique

Fog Feed Technique

disadvantage of hydroponic systems
Disadvantage of Hydroponic Systems
  • High cost of construction, equipment, fuel, and skilled workers.
  • Large-scale operations don’t exist.
  • It is suitable for places where land or water is too scarce or too valuable to use for farming such as in cities (roof-top community gardens), not useful for large-scale operations.
soil less solutions
Soil-less Solutions