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48 Cards in this Set

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Agriculture
Practice of cultivating soil, producing crops, and raising livestock for human use and consumption
Cropland
Currently covers 38% of Earth
Rangeland
Pasture used for livestock
Soil
Mix of rock, organic matter, water, gases, nutrients, and microorganisms
Traditional agriculture
-10,000 years ago
-Needed human and animal energy, hand tools and simple machines
Monoculture
Planting a single crop
Green revolution
Applied technology to boost crop yields
What are the two types of Agriculture?
-Industrialized= demand-based, high use of fossil fuels, large tracts of land, fertilizers/pesticides, monoculture, high yield
-Subsistence= resource-based, smaller scale, human labor, polycultures, fewer pesticides/fertilizer
Parent material
Base geological material in a location, can be composed of volcanic, glacier, sediments, or bedrock
Weathering
First step in the formation of soil
Erosion
Process of moving soil from on area to another, usually depletes topsoil
Horizons
Soil from any given location decided into layers
Soil profile
Cross-section from bedrock to surface
O horizon
Uppermost layer of soil consisting of mostly organic matter
A horizon (topsoil)
Below O horizon, mostly inorganic minerals with some organic matter and humus
E horizon
Below A horizon, zone of eluviation
Leaching
Picks up particles in soil and transports them elsewhere
B horizon
Layer beneath A and E that contains materials leached from A and E
C horizon
Beneath B, contains rock particles that are larger
R horizon
Below C, parent material (bedrock)
Clay
Particles less than .002mm in diameter
Silt
Particles between .002-.05 mm
Sand
Particles .05-2 mm
Loam
Soil with even mixture of particles
Desertification
Loss of more than 10% productivity due erosion, soil compaction, forest removal, overgrazing, drought, ect.
Dust Bowl
-1903s in Middle states
-Grassland and drought w/o irrigation
-Change from petennial grasses to annual crops
-Dust storms
Conservation districts
Districts in counties that promoted soil-conservation
Crop rotation
Practice of alternating the kind of crop grown in a particular field from one season/year to the next
Contour farming
Plowing furrows along natural contour of land
Intercropping
Planting of alternating bands of different crops across a slope
Terracing
Cutting level platforms into hillsides
Shelterbelts
Rows of trees planted along edges of fields to break wind
Irrigation
Artificial provision of water
Salinization
Problem, buildup of slats in surface of soil layers
Inorganic fertilizers
Synthetically manufactured mineral supplements
Organic fertilizers
Natural materials used
Plowing
-Turning top 6 inch of soil over
-To reduce weeds (among other)
-Seed bed preparation
Conservation tillage
-Reduces # of time land is plowed
-"No till"= don't plow, harvest and leave remains, plant new seed in between old
What are on-site and off-site effects?
-On-site effects= w/in field, soil degredation, lack of genetic diversity, pesticide buildup,
-Off-site effects= erosion, runoff, h2O depletion
What was the Soil Conservation Act?
-1935
-Created conservation districts at a local level
-Enforced planting of hedgrows (wind blocks)
What are the pros and cons of conservation tillage?
-Pros= less erosion, more organic matter (more nutrients), less energy use
-Cons= buy new equipment, weeds (pests in old stocks)
What are pros and cons of irrigation?
-Pros= allows planting on marginal land
-Cons= salinization, <50% of water ends up in plant/soil
What is Drip Irrigation?
Main pipe with feeder hoses, very effective drips water at base of plant, but expensive
What are problems with fertilizer?
-Eutrophication from runoff
-Overuse (at some point, too much will actually decrease yield)
Organic vs. conventional agriculture
-Organic= high organic content (retains water and nutrients), lower energy, soil better, better in drought
-Convential= nutrients the same
How long does soil take to form?
500 years
What are the steps in soil formation?
1. Physical weathering= freezing rain, thermal expansion
2. Chemical weathering= acid rain
3. Biological weathering= life form is involved (lichen)
What (again) are the horizons in the soil profile?
-O= organic, leaf litter
-A= topsoil, darker, high-organic matter or humus
-E= eluviation: removal of nutrients from leaching
-B= illuviation: accumulation of clay from A horizon
-C= broken up parent rock
-R= parent rock (bedrock)