Chapter 9

Soil Conservation Act of 1935

U.S. legislation that provided for control and prevention of soil erosion, delegated all activities relating to soil erosion to the Secretary of Agriculture, and established the Soil Conservation Service

erosion

the movement of soil from one location to another

overgrazing

This occurs when plants are exposed to intensive grazing for extended periods of time or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, or by overpopulations of native or non-native wild animals.

water logging

when soil becomes oversaturated

eutrophication

overuse of fertilizers can result in excess nutrients, such as phosphorus and nitrogen, running off into rivers and lakes, resulting in algal blooms and the overproduction of other plant life that can destroy an aquatic ecosystem

soil structure

a measure of the "clumpiness" of soil

Food Security Act of 1985

law that requires farmers to adopt soil conservation plans and practices as a prerequisite for receiving government benefits

salinization

salts that build up in the soil after water evaporates

drip irrigation

an environmentally conscious method of irrigation that involves arranging hoses in such a way that water drips from holes in the hoses directly onto the plants

soil texture

refers to the amounts of the different types and sizes of mineral particles in the soil

intercropping

a method of farming on a slope that slows erosion by planting different types of crops in alternating bands to provide a more complete ground cover

weathering

physical, chemical, & biological processes that break down rocks and minerals

soil permeability

refers to the rate at which water and air move from upper layers of soil to lower layers of soil

soil profile

a cross-section soil sample that shows all of the horizons from the surface to the bedrock

U.N. Food & Agriculture Organization

This organization promotes soil conservation and sustainable agriculture throughout the world.

A horizon

This layer of soil contains mineral material, living organisms, and humus.

Conservation Reserve Program

pays farmers to stop cultivating highly eroding cropland

clay

very fine soil particles with low water permeability

soil porosity

refers to the size of the spaces between particles of soil

Dust Bowl

severe drought and soil degradation in the prairies in the 1930s

crop rotation

the practice of alternating the kind of crop grown in a particular field from one season or year to the next

inorganic fertilizer

mined or artificially produced fertilizers added to soil to promote plant growth

agriculture

the practice of raising crops & livestock for human use and consumption

polyculture

the agricultural practice of growing multiple crops in the same area at the same time

green revolution

refers to the significant increase in agricultural productivity resulting from the introduction of high-yield varieties of grains, the use of pesticides, and improved land management techniques

subsistence agriculture

the type of agriculture where families produce only enough food for themselves and do not utilize pesticides, large-scale irrigation, or teams of laboring animals

cropland

land used to grow plants for human use

soil

a complex plant-supporting system

desertification

the degradation of land in arid environments due to erosion, soil compaction, forest removal, overgrazing, drought, salinization, climate change and depletion of water; it causes a loss in food production

compost

an organic fertilizer mixture produced when decomposers break down food and plant material in a controlled environment

black blizzards

the nickname for extreme dust storms that occurred during the Dust Bowl

contour farming

a method of farming on a slope that involves plowing furrows sideways across the hillside, perpendicular to the slope, to help prevent the formation of rills and gullies

traditional agriculture

agriculture that uses primarily human and animal power

physical weathering

This type of weathering is caused by wind, rain, thermal expansion & contraction, and water freezing. It breaks down rocks without triggering a chemical change in the parent material.

loam

soil consisting of an equal mixture of clay, silt, sand and humus

horizon

refers to a layer of soil

gully erosion

a severe form of water erosion where large trenches and ditches, usually more than a foot deep, are cut into the soil

leaching

the process whereby solid particles suspended or dissolved in liquid are transported to another location

O horizon

the litter layer of soil comprised of decaying organic matter

humus

rich, organic material produced by the decomposition of plants and animals

B horizon

leached materials are deposited there

terracing

a method of farming on extremely sloping land

chemical weathering

This type of weathering results when water and other substances chemically interact with the parent material. Warm, wet conditions usually accelerate this process.

industrial agriculture

agriculture that utilizes large scale mechanization and fossil fuels, chemical fertilizers, and pesticides to increase crop yields

monoculture

the agricultural practice of producing or growing one single crop over a wide area

conventional irrigation

an inefficient method of irrigation that loses a great deal of water to evaporation

topsoil

the portion of the soil, also known as the A horizon, that holds the most nutrients and is the most important for ecosystems and agriculture

cover crops

crops planted whose primary purpose is to prevent soil erosion, improve soil quality, or prevent pest

hunter-gatherer

individuals whose primary means of survival involves foraging for all their food lik

rangeland / pasture

land used for grazing livestock

bedrock

the continuous mass of solid rock that makes up the earth's crust

parent material

the geological material that makes up the base of the soil in an area

silt

a component of soil comprised of particles of sediment larger than clay but smaller than sand

R horizon

This soil layer contains the bedrock.

E horizon

Sand & silt are concentrated in this soil layer.

C horizon

large chunks and pieces of partially broken down parent material.

splash erosion

water erosion caused by the impact of water droplets, such as rain, hitting the soil

swidden agriculture

a method of agriculture that involves clearing an area of land of all vegetation, usually through slash & burn, so as to prepare the land for cultivation of crops

plowpan

a condition of the soil or subsoil in which the soil grains become cemented together and do not allow the infiltration of water or gases

no till farming

a way of growing crops from year to year without disturbing the soil

sand

large particles of soil with high water infiltration and high porosity

windbreak / shelterbelt

a technique to reduce wind erosion that involves planting rows of trees or other tall plants along the edges of fields slow the wind

sheet erosion

the movement of soil particles downslope by water flowing overland as an entire sheet instead of in definite channels or rills

animal manure

animal feces added to soil to provide nutrients and increase soil fertility

organic fertilizer

naturally occurring fertilizers, such as compost, manure and minerals, that increase soil fertility

green manure

fresh vegetation plowed into the soil to provide nutrients and increase soil fertility

rill erosion

the formation of numerous small closely spaced channels, usually less than a few inches deep, cut into the soil due to the uneven removal of surface soil by streamlets of running water

biological weathering

This type of weathering occurs when living things, such as tree roots and lichen, break down the parent materials by physical or chemical means.