AGEN 2363 Chpt. 2 notes. Soil erosion and civilization.
I. N. Iraq – Oldest known area of organized crop cultivation, about 11,000 years ago.
Wheat, barley grown. Area between Tigris and Euphrates rivers first region of widespread
crop cultivation. Known as ‘Mesopotamia’.
Nebuchadnezzr: his kingdom logged most of the cedars, used irrigation This caused massive
erosion from overgrazed, unprotected hills with sediment filling up irrigation canals.
Stories from other areas:
Egypt. Agriculture along Nile river. Natural floods annually deposited rich, silty soil and
allowed for easy irrigation using small levees, gates, and re-lifts. Aswan Dam stopped
the flooding, annual silt deposits, and increased infrastructure for watering.
Lebanon, Israel, Jordan, and Syria. About 50% of upland soil eroded down to bedrock due to
over-grazing. Sedimentation buried many lowland agriculture fields and towns.
Main problems are over-grazing, wind and water erosion, loss of productive land.
Modern Israel agriculture is the most efficient and productive. They are leaders in
greenhouse production and micro-irrigation methods of fruits and vegetables.
N. Africa. Greeks, Romans very efficient farmers/irrigators along Mediterranean coast. After
the fall of these empires, over-grazing accelerated erosion and soil decline.
Greece and Italy. Greek civilizations in these areas initiated many soil conservation practices
such as fallow-farming, terracing, Over-population increased soil erosion/sedimentation
and decreased productivity. Imported grain from N. Africa and Italy allowed conversion
of land to vegetables, grapes, and olive – which were less destructive to soil.
Great Britain. Soil erosion not as bad due to mild rainfall, much like our Pacific NW.
Scotland had greatest losses due to steeper hills. Long, narrow fields common.
France, Germany, and Switzerland. Various problems with soil erosion in the steeper soils.
Ancient bench terraces, around 1000 years old, established in France, some on 45 degree
Eastern Europe. Not as severe erosion problems due to gentle rains. Crop rotations, use of
manures and crop residue cycling utilized from around 500 years ago to present.
Soviet Union. Some problems in a few areas with deforestation of hilly ground, over-grazing,
and subsequent wind erosion, especially from sandier soils.
Netherlands, Belgium. Small tract reclamation of land from broad, shallow sea beds.
Problem was pumping out the sea water and allowing natural rain to rinse out the
salty soils. Process takes about 3-5 years.
China. Most of China is too steep or dry for productive crop production. Severe erosion
occurred in the extensive loess hills. Soil erosion has been severe but contour
terracing started about 760 A.D. and has reclaimed much ground. Sedimentation
increased flooding, ruined irrigation systems. Modern advances are occurring,
especially the use of fertilizers.
S. Central Asia. Monsoon climate utilized in production of rice. Extensive deforestation
in the mid-1800’s caused much erosion/sedimentation. Also salt buildup.
Peru. Incas were expert soil and water conservationists, using bench terraces, irrigation canals,
and manures. Mayas cultivated low lands in Central America but lost them due to
deforestation – erosion – sedimentation/flooding/irrigation destruction. Tropical
deforestation recently in the Amazon regions is accelerating soil erosion/sedimentation.
Salt pollution ruined many soils along coastal areas and led to the demise of many
U.S. Massive soil erosion damage occurred from the mid-1800’s until the mid-1900’s.
‘Dust bowl’ days led to formation of S.C.S., now NRCS.
Africa. ‘Shifting’ agriculture (define) of root crops and millets kept most severe erosion
controllable until deforestation and mining led to massive erosion. Sub-soils not very
fertile and infra-structure not there to educate and incorporate erosion control. Drought,
over-grazing, increased populations, and wars have hurt soil conservation efforts.
BOTTOM LINE: Historically, what are the major causes of soil erosion problems? Discuss.
- Over grazing, deforestation, sedimentation, over-populations, politics, infrastructure, salts, labor shortages, others. discuss.