Download Soil Issues and Conservation

Warm-Up Review
1. What are the 5 components in soil?
2. Air and Water make up about _____ % of
soil by volume.
3. What is an example of mechanical
weathering?
4. What process transports sediments from
one place to another?
5. During a rainstorm, which soil is more
likely to have poor drainage: clayey or
sandy soil?
Soil Issues and Conservation
Soil Degradation
Soil used as a resources leads to degradation
Renewable resources BUT it takes 200-1000
years to form 1” of top soil
So, it must be protected, conserved
3
What are the main causes of soil degradation?
Crop production
Livestock production
Deforestation
Soil Issues
Erosion
Desertification
Salinization
Soil Erosion
 Erosion – wearing away
of soil by wind or water
 Causes – farming: loosens soil so it is
more easily eroded by wind or water
 Problems –
when topsoil wears away, crops cannot be
grown
Sediments in rivers, lakes, etc.
The Dust Bowl
Soil Erosion
The Great Dust Bowl 1930
 Massive effort plowing of
prairies to plant wheat started
during WWI
 Drought
 Huge dust storms
Lead to the Soil Conservation Act (SCA), which
established the Soil Conservation Service (SCS)now known as the Natural Resources
Conservation Service (NRCS)
 Includes soil, and water quality and pollution
7
Desertification
 Process by which land in arid or semiarid areas
becomes more desert-like because of human
activities
 Causes – overgrazing, crops are planted too
frequently, farming methods
Salinization
 Occurs in arid and semi-arid regions where lots of
groundwater is used to irrigate crops
 High evaporation rate
 Salts build up in soil over time as groundwater
evaporates on surface
 Plants have difficulty growing in salty soil
Soil Conservation Strategies
http://www.mda.state.mn.us/protecting/conservation
/practices.aspx
Google: Soil conservation practices Minnesota
Contour Farming
Tilling the soil
No-till Farming
Ridge-till farming
Mulch-till farming (1)
Terracing
Cover crops
Windbreaks
Strip cropping
Wrapping Up:
Describe 3 methods of soil conservation
used in agriculture
2 Provide one reason why soil conservation
is important.
3 What region of the country would soil
salinization be a problem?
1
Answers
 1. No-till/reduced till, windbreaks, cover crops,
contour farming, strip-cropping, terrace farming,
agro-forestry
 2. Top soil takes a long time to regenerate, if you
lose topsoil, you lose nutrients, runoff a pollutant
 3. Southwest and California (arid and semi-arid
climates reliant on irrigation)
Soil Conservation Strategies
 No till/reduced till agriculture
 Leaves debris in field after harvest
 Protects from wind/water; Decomposition recycles nutrients
 Less CO2 emissions
23
Soil Conservation Strategies
 Cover-Cropping
 Planting a crop that covers the soil in fall, winter, and early
spring
 Legumes are sometimes used to restore Nitrogen to soil and
improve fertility
Soil Conservation Strategies
 Windbreaks or shelter breaks
Wind barricade; trees or fencing
Reduces soil loss from wind
Soil Conservation Strategies
 Contour farming (low slopes) & Terracing (steep slopes)
 Plowing & planting perpendicular to slope; large steps cut
into hillside; Both control water flow
Soil Conservation Strategies
 Intercropping & Agroforestry (alley cropping)
 Multiple plant species in one area
 Tall and short plantings; wind and water flow controlled
Soil Conservation Strategies
 Silt Fencing at Construction sites
 Keeps sediments on-site, less runoff
Farming Lingo
 “Tillage” = plowing. Farmers plow their fields to expose the
topsoil for seeds to be planted.
 Ex: “No-till” farming does NOT plow the soil
 “Yield”- the amount of a particular crop harvested per unit
area: 50 bushels of corn/acre
 “Acre”- 43,560 ft2, American farm unit
 “Hectare”- 10,000 m2, Metric farm unit (>acre)
 “Inputs”- resources put into growing a particular crop:
fertilizers, pesticides, seeds, equipment, plowing