U.S. Land Use, Urbanization, and Soil Science: Key Concepts

What percentage of land in the United States is used for crops and livestock?

52%

What percentage of land in the United States is designated as forests and natural areas?

34%

What percentage of land in the United States is used for intensive human use?

11%

What major geographical features influenced early U.S. land use?

Waterways provided the primary method of transportation.

How did the Industrial Revolution impact urbanization in the U.S.?

It led to migration from farms to industrial jobs in cities.

How many Americans migrated from the countryside to cities between 1870 and 1920?

11 million

What was the primary source of immigration to U.S. cities during the late 19th century?

25 million immigrants, mostly from Europe.

What cultural opportunities attracted people to urban areas in the U.S.?

Professional baseball, concert/music halls, and amusement parks.

What was the population percentage living in urban areas by 1890?

28%

By 1920, what was significant about the U.S. population distribution?

More Americans lived in towns and cities than in rural areas.

What percentage of Americans lived in rural areas as of 2017?

20%

What was the impact of the Second Industrial Revolution on land use?

It introduced assembly-line production and new technologies like electricity.

What environmental issue prompted migration from central cities to suburbs?

Polluted waterways due to industrial activities.

What was the Cuyahoga River known for in the context of pollution?

It caught fire multiple times, leading to a major cleanup initiative.

What significant legislation was passed in response to the Cuyahoga River fires?

The Clean Water Act (1972) and the establishment of the EPA (1970).

How did the perception of land change during the industrial era?

Land began to be viewed as a commodity rather than a non-renewable resource.

What are two practices that contributed to urban sprawl?

Zoning ordinances isolating services from housing and low-density planning for automobile access.

What is urban sprawl?

A pattern of unplanned, low-density housing and commercial development outside of cities.

What is zoning in land-use regulation?

Zoning is a regulation that restricts the uses to which land in a region can be put, often designating mapped zones for specific uses.

What is the primary purpose of zoning?

The primary purpose of zoning is to segregate incompatible land uses, such as residential, commercial, and industrial.

How does zoning help preserve community character?

Zoning prevents new development from interfering with existing uses and helps maintain the character of a community.

What types of activities can zoning regulate?

Zoning can regulate activities such as open space, residential, agricultural, commercial, or industrial uses.

What aspects of development can zoning control?

Zoning can control densities, building heights, space occupancy, building location, and proportions of different types of space on a lot.

What are some environmental consequences of urban sprawl?

Environmental consequences include air pollution, water pollution, loss of sensitive areas, increased flood risks, and reduced quality of life.

What is the relationship between automobile dependency and urban sprawl?

Automobile dependency contributes to air and water quality reductions and the accelerated depletion of fossil fuels.

What are the three ways urban sprawl occurs?

1. Development of exclusive suburbs, 2. Tract development of similar residential units, 3. Ribbon sprawl with commercial buildings along highways.

What issues are associated with the growth of cities according to Laudato Si'?

Cities face issues like pollution, urban chaos, poor transportation, visual pollution, noise, and inefficient use of resources.

What is land-use planning?

Land-use planning is a branch of urban planning that seeks to order and regulate land use efficiently and ethically to prevent conflicts.

What does smart growth promote?

Smart growth promotes compact, transit-oriented urban communities that maximize community goals and avoid wasteful sprawl.

Which federal agency manages the most land in the U.S.?

The Bureau of Land Management (BLM) manages 244.4 million acres.

What is the role of the National Park Service?

The National Park Service preserves significant scenic areas and nature reserves, such as Yellowstone National Park.

What types of areas do national monuments preserve?

National monuments preserve unique cultural or natural features.

What percentage of U.S. land is managed by federal agencies?

Federal agencies manage about 615.3 million acres, or 27% of the U.S. land base.

What is the significance of the first national park?

Yellowstone National Park, established in 1872, was the first national park in the U.S.

What is the significance of the first national monument?

Devils Tower National Monument, established in 1906, was the first national monument.

What is a key characteristic of smart growth?

Smart growth focuses on the efficient use of land to create livable urban environments.

What are the consequences of increased impervious surfaces due to sprawl?

Increased impervious surfaces leads to water pollution and heightened flood risks.

How does urban sprawl affect open space?

Urban sprawl leads to reductions in open space and environmentally sensitive areas.

Igneous Rocks

Formed from the cooling of molten rock.

Sedimentary Rocks

Formed in layers as the result of moderate pressure on accumulated sediments.

Metamorphic Rocks

Formed from older 'parent' rock (either igneous or sedimentary) under intense heat and/or pressure at considerable depths beneath the earth's surface.

Crust

Layer from 4-25 miles thick consisting of sand and rock.

Mantle

Rock layer about 1,750 miles thick that reaches about half the distance to the center of the earth.

Outer Core

Mass of molten iron about 1,425 miles deep that surrounds the solid inner core.

Inner Core

Mass of solid iron with a temperature of about 7000ºF.

Soil

The unconsolidated mineral or organic material on the immediate surface of the earth that serves as a natural medium for the growth of land plants.

Dead Soil

Displaced soil; none of the minerals, nutrients, or living organisms found in soil.

Roles of Soils

7 General roles: 1. Media for growth of plants 2. Modify atmosphere (releasing and absorbing gases (CO2, CH4, H2Ov) 3. Habitat for animals 4. Absorbing and purifying water in terrestrial systems 5. Process recycled nutrients (geochemical cycles) 6. Media for human engineering and construction 7. Filtering water before it percolates into aquifer.

CLORPT

A mnemonic for soil formation factors: Climate, Organisms, Relief (Landscape), Parent Material, Time.

Soil Organic Matter

Most of our productive agricultural soils have between 3-6% organic matter.

Humus

Final product of decomposition; products of organic residues and materials synthesized by microorganisms.

Effect of Slope on a Soil Profile

Soils are different depending on the location in the slope that they are located.

Parent Material

Every soil formed from parent material deposited at the Earth's surface.

Time in Soil Formation

As soil ages, it starts to look different from its parent material because soil is dynamic.

Soil Formation

Soil is formed through various processes influenced by climate, organisms, relief, parent material, and time.

Soil Composition

Soil consists of minerals, organic matter (humus), water, and air.

Soil Organisms

¼ teaspoon of fertile soil contains various microorganisms including 50 nematodes, 52,000 algae, 72,000 amoebae, 111,000 fungi, 2,920,000 actinomycetes, 25,280,000 bacteria, and 50,000 protozoans.

Soil Development

Soils develop more quickly in warm, moist climates.

Gravity and Water in Soil Formation

Gravity and water move soil particles down the slope, resulting in deeper soils forming at the bottom of a hill.

Soil Components

Minerals, water, air, organic matter, and organisms.

Soil Profile

Observable layers in the soil, each with a distinct combination of characteristics.

Soil Horizons

Collectively, all the horizons in a particular location give each soil a distinctive soil profile.

O Horizon

Organic/humus layer, mostly organic matter; decomposing leaves, etc.; may or may not be present depending on the soil.

A Horizon

Topsoil, rich in humus and minerals important to plant growth; organic rich.

E Horizon

Eluviated zone of leaching, where water leaches minerals to the next zone, leached of clay, minerals, and organic matter.

B Horizon

Subsoil, called the zone of accumulation; rich in minerals that leached from the A or E horizons; organic poor.

C Horizon

Parent material, composed of unconsolidated parent material, weathered bedrock.

R Horizon

Bedrock, a mass of rock such as granite, basalt, quartzite, limestone or sandstone that forms the parent material for some soils.

Soil Classifications

Three major types: Grassland, Forest, Desert.

Soil Structure

The arrangement of soil particles into clumps (peds) or aggregates.

Peds

Soil clumps that have specific shapes depending on composition and conditions in which they formed.

Soil Texture

Determined by size of mineral particles within the soil.

Gravel

Fragments greater than 2.0 mm diameter.

Sand

Particles ranging from 0.5 to 2.0 mm.

Silt

Particles ranging from 0.002 to 0.05 mm.

Clay

Particles less than 0.002 mm diameter.

Soil Color

Influenced primarily by soil mineralogy, indicating what is in a specific soil.

Iron-rich Soils

Soils high in iron are deep orange-brown to yellowish-brown.

Organic Matter-rich Soils

Soils high in organic matter are dark brown or black.

Soil pH

The pH of the soil solution is important as it carries nutrients such as nitrogen (N), phosphorus (P), and potassium (K) that plants need.

Erosion

Wearing away and transportation of soil by water, wind, or ice.

Worldwide Soil Erosion Estimate

Approximately 36 billion tons of soil eroded per year.

U.S. Average Soil Loss

Average soil loss is 4.63 tons per acre per year.

Splash Erosion

First stage of the erosion process occurring when raindrops hit bare soil, breaking up soil aggregates.

Sheet Erosion

The uniform removal of soil in thin layers by raindrop impact and shallow surface flow.

Sheet Erosion Effects

It results in loss of the finest soil particles that contain most of the available nutrients and organic matter in the soil.

Early Signs of Sheet Erosion

Bare areas, water puddling as soon as rain falls, visible grass roots, exposed tree roots, and exposed subsoil or stony soils.

Active Sheet Erosion Indicators

Soil deposits on the high side of obstructions such as fences may indicate active sheet erosion.

Rill Erosion

Erosion that results in small, short-lived and well-defined streams.

Rill Erosion Formation

Occurs when runoff water forms small channels as it concentrates down a slope.

Rill Erosion Depth

Shallow drainage lines less than 30cm deep.

Gully Erosion

Advanced rill erosion.

Gully Erosion Characteristics

Channels deeper than 30cm that cannot be removed by normal cultivation.

Gully Erosion Formation

Occurs when smaller water flows concentrate and cut a channel through the soil.

Dust Bowl

A period in the 1930s affecting Kansas, Oklahoma, Texas, New Mexico, Nevada, and Arkansas.

Shelterbelt Project

Started by FDR in 1934 in response to the Dust Bowl to create windbreaks in the Great Plains states.

Plains States Forestry Project

A project created by the Works Progress Administration in 1940 to encourage planting trees as a method of soil conservation.

Sustainable Agriculture

An integrated system of plant and animal production practices having a site-specific application that will over the long-term satisfy human food and fiber needs.

Soil Quality Management Components

Enhance Organic Matter, Avoid excessive tillage, Manage pests and nutrients efficiently, Prevent soil compaction, Keep the ground covered, Diversify cropping systems.

Ways to Conserve Soil

Manage topography, Provide ground cover, Reduced Tillage.