Environmental Science Test 4

How is the world’s land used?

34% of the total is for agricultural practices

How is land used in the United States?

• 52% - Crops (ag land) and livestock

• 34% - Forests and natural areas

• 11% - Intensive human use

• Gathered together, cropland would take up more than a fifth of the 48 contiguous states

Where are most pasture/range land and cropland located?

• pasture and range are concentrated in the West

• cropland is mainly in the central U.S.

Historically, what provided the primary method of transportation?

Waterways

• this allowed the exploration and development of commerce

• early towns usually built near water

• think of all larger cities along the Mississippi River

Why did cities grow in North America?

Industrial Revolution

• people migrated from farms to industrial jobs in cities

• 11 million Americans migrated from countryside to cities between 1870 and 1920

European Immigrants

• congregated in cities where jobs were available

• 25 million immigrants, most from Europe, moved to U.S.

Cultural, Social, and Artistic opportunities

• Examples: professional baseball, concert/music halls, amusement parks

What percent of the American population lived on farms or ranches over the years?

• 1790: 90% of the population lived on farms or ranches

• by 1890: 28% of Americans lived in urban areas

• by 1920: more Americans lived in towns and cities than in rural areas

• today: 1 in 5 live in rural areas, only 2% live on farms or ranches

Second Industrial Revolution (Technological Revolution)

Following Civil War

• 1870-1914

• assembly-line production

• new technologies (telephone, automobile, electricity)

What happened to waterways during IR?

Lack of control over industry activities led to polluted, undesirable waterways

• as roads and rail transport became more common, many left waterway areas

• agricultural land surrounding towns was converted to housing

• land began to be viewed as a commodity, not as a non-renewable resource to be managed

Polluted Waterway Example

Cuyahoga River

• caught fire more than once

• 1968- citizens passed $100 million bond initiative to fund the Cuyahoga’s cleanup

• June 1969- fire caused by oil slick from industry alongriver led to damage of two railroad bridges and was the last straw

• Led to passage of Clean Water Act (1972)

• EPA (1970) 

Excerpt writing on human pop distance to water in USA

• “humans moved closer to major rivers in pre-industrial periods but have moved farther from major rivers after 1870”

• “humans were preferentially attracted to areas overlying major aquifers since industrialization due to the emergent accessibility of groundwater in the 20th century”

US Farmland under threat of urbanization

• US lost 11 million acres of farmland to development in past 2 decades

• following covid, more people moved out of cities than before: overall 4.9 million Americans left cities for suburbs or rural areas

Migration from the Central City to the Suburbs

the convenience of a personal automobile escalated decentralized housing patterns and diminished importance of mass transit

• led to decreased energy efficiency

• increased cost of supplying utility services

Urban Sprawl

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

• land-use practices are fundamental to sustainability

2 practices that have contributed to urban sprawl

1. zoning ordinances that isolate employment and shopping services away from housing locations

2. low-density planning aimed at creating automobile access to increasing expanses of land

zoning

land use regulation that restricts the uses to which land in a region can be put

• often planners making zoning decisions represent business or developing interests

• primary use of zoning is to segregate uses that are thought to be incompatible

• also used to prevent new development from interfering with existing uses and/or to preserve the “character” of a community

environmental consequences of urban sprawl

“air pollution resulting from automobile dependency, water pollution caused in part by increases in impervious services, the loss or disruption of environmentally sensitive areas, such as critical natural habitats (e.g., wetlands, wildlife corridors), reductions in open space, increased flood risks”

Urban sprawl occurs in 3 ways

1. development of exclusive, wealthy suburbs adjacent to the city

2. tract development is the construction of similar residential units over large areas

3. ribbon sprawl consists of commercial/industrial buildings lining highways connecting housing developments to the central city

68% of world population projected to live in urban areas by 2050

Laudato Si’ on urban sprawl

“we were not meant to be inundated by cement, asphalt, glass and metal, and deprived of physical contact with nature”

Land-use planning

general term used for a branch of urban planning encompassing various disciplines which seek to order and regulate land use in an efficient and ethical way, thus preventing land-use conflicts

• evaluates: needs and wants of a population, land characteristics and value, and various alternative solutions to land use before changes are made

Smart Growth

an approach to land-use planning

• promotes compact, transit-oriented urban communities that are attractive and livable

• smart growth focuses on the planning and layout of communities and the efficient use of land to maximize community goals and avoid wasteful sprawl

5 major federal land management agencies

1. Bureau of Land Management (BLM)

2. Forest Service

3. Fish and Wildlife Service

4. National Park Service

5. Department of Defense

together they manage about 615.3 million acres, or 27% of the U.S. base

what percentage of land in the west does the U.S. government own?

47%

National Parks

• Preserve nationally and globally significant scenic and nature reserves

• Yellowstone National Park was the first in 1872

National Monuments

preserve a single unique cultural or natural feature

• Devils Tower National Monument was the first in 1906

Thomas Jefferson quote about soil

“Civilization itself rests upon the soil”

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 under intense heat and/or pressure at considerable depths beneath the earth’s surface

Earth’s Geography

• Crust

• Mantle

• Outer Core

• Inner Core - mass of solid iron

3 kinds of weathering

• physical weathering (wind, rain, thermal expansion and contraction)

• chemical weathering (water and gases)

• biological weathering (tree roots and lichen)

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

• consists of minerals, organic matter (humus), water, air

• the mineral and organic matter that supports plant growth on the earth’s surface

dirt

dead soil: displaced soil; none of the minerals, nutrients, or living organisms found in soil

roles of soils

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 (water in soil → drawn back to surface)

5. process recycled nutrients (geochemical cycles)

6. media for human engineering and construction

7. filtering water before it percolates into aquifer 

Soil Formation: CLORPT

• Climate

• Organisms

• Relief (Landscape)

• Parent Material

• Time

CLORPT: Climate

soils develop more quickly in warm., moist climates

CLORPT: Organisms

• most of our productive agricultural soils have between 3-6% organic matter

3 major types of organic matter

Fertility

1. plant residues and living microbial biomass (small organisms)

2. decomposing (active) organic matter, which is detritus

Structure

3. stable organic matter (humus)

Humus

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

CLORPT: Relief (Landscape)

• how much sunlight the soil gets and how much water it keeps is a result of the shape of the land and the direction it faces

• deeper soils form at the bottom of the hill 

CLORPT: Parent Material

every soil formed from parent material deposited at the Earth’s surface

CLORPT: Time

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

• soils components constantly change

Soil Profile

• observable layers in the soil

• each has distinct combination of characteristics

• 6 major types: O,A,E,B,C,R

soil profile: O and E Horizon

• 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

3 major types of soil classifications

1. grassland

2. forest

3. desert

most can be classified as grassland or forest

Soil Structure

the arrangement of soil particles into clumps (peds) or aggregates

• structure correlates to the pore space in the soil

Soil Texture

determined by size of mineral particles within the soil

Soil Color

Soil color is influenced primarily by soil mineralogy- telling us what is in a specific soil

• soils high in iron are deep orange-brown to yellowish-brown

• soils high in organic matter are dark brown or black

• color can tell us how soil behaves (drains well= brightly colored, often wet and soggy= mottled pattern of grays reds and yellows)

the importance of soil pH

The pH of soil is very important because soil solution carries in it nutrients such as Nitrogen, Phosphorous, Potassium, that plants need in specific amounts to grow, thrive, and fight off diseases

• N- foliage

• P- root formation and energy transfer

• K- for seed formation/germination and sugar formation

Erosion

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

• removal of a substance from one area and transported towards another area

biggest category is water erosion

worldwide and U.S. Soil erosion numbers

Worldwide: estimate ~36 billion tons soil eroded each year

• conservation practices could save over a billion tons of soil per year

U.S.: average soil loss → 4.63 tons per acre per year

Splash Erosion

• first stage of the erosion process

• it occurs when raindrops hit bare soil

• the explosive impact breaks up soil aggregates so that individual soil particles are ‘splashed’ onto the soil surface

Sheet Erosion

• the uniform removal of soil in thin layers by raindrop impact and shallow surface flow

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

• early signs of sheet erosion include bare areas, water puddling as soon as rain falls, visible grass, etc.

Rill Erosion

• erosion that results in small, short-lived and well-defined streams

• occurs when runoff eater forms small channels as it concentrates down a slope

• intermediate stage between sheet erosion and gully erosion

Gully Erosion

• advanced rill erosion

• occur when smaller water flows concentrate and cut a channel through the soil

Dust Bowl

1930’s

• Kansas, Oklahoma, Texas, New Mexico; from Nevada and Arkansas

1924- Shelterbelt Project

• started by FDR in response to Dust Bowl- to create windbreaks in the Great Plain states

National Resources Convention Service (NRCS)

• 1994

• Started as Soil Conservation Service (SCS) in 1935

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

1. manage topography

2. provide ground cover

3. reduced tillage

Manage Topography

Crop rotation, contour plowing, strip farming, intercropping, terracing, and shelterbelt reduce soil erosion, retain water, and make use of hillsides

Provide ground cover

• crop residue reduces water and wind erosion

• interplanting different crops crowds out weeds

• mulch- reduces erosion and weed growth

Crop rotation

• can help growers avoid problems, such as weeds, insect infestation, etc

• can also reduce economic and environmental risks, improve soil health, and increases yields

contour plowing

aligning ridges, furrows, and roughness formed by tillage, planting and other operations to alter velocity and/or direction of water flow to around the hillslope

• contour lines create a water break

• reduces sheet/rill/wind erosion

• increase water filtration

Shelterbelts

vegetative barriers that are designed to reduce wind speed and provide sheltered areas on the leeward (the side away from the wind) and windward (side toward the wind) sides of the shelterbelt.

• can be used to reduce the impact of accelerated soil erosion

• can decrease wind speed in the sheltered zone to a level below the threshold for soil movement 

mulch

a layer of material applied to the surface of soil

reduced tillage

• minimum tillage: disc or chisel plow with reduced turnings of soil

• conservation tillage: coulter plow; opens soil just for seed insertion

• no-till/strip-till: seed drilled directly through mulch/crop residue

tillage

agricultural preparation of soil by mechanical agitation

Development of Agriculture

Development of agriculture involved manipulating the natural environment to produce food desired by humans

• ~12,000 years ago in Fertile crescent

• allowed an increase in size of the human population

Labor-intensive agriculture

3 situations favor this type of agriculture:

1. the growing site does not allow mechanization

2. the crop does not allow mechanization

3. the economic condition does not allow purchase of mechanized equipment (primary reason for use of labor-intensive agriculture)

Mechanized monoculture

• typical of industrialized countries

• fossil fuel replaces human muscle power

• requires large amounts of energy and flat land

• monocultures promote more efficient planting, cultivating, and harvesting

• farmers often rely on hybrids to provide uniform monocultures

Labor reduction in the U.S.

• 1913: 135 hours of labor required to produce 2,500 kg of corn

• 1980: 15 hours of labor required to produce 2,500 kg of corn

• 2010: 1.2 hours of labor per acre

U.S. Corn Yields

increased steadily from nearly 85 bushel per acre in 1980 to >120 bushel per acre (2000) and 168 bushel per acre (2019)

Fertilizer Production

• natural gas is used in the process as the source of hydrogen to combine with nitrogen to make the ammonia that is the foundation of the nitrogen fertilizer

• petroleum based products not used

• haber-bosch process

problems with mechanized monoculture

1. protecting the soil

2. loss of genetic diversity

3. reliance on fertilizer and pesticides

Green Revolution

• greatly increased worldwide food production

• “great increase in production of food grains (especially wheat and rice) that resulted in large part from the introduction into developing countries of new, high-yielding varieties, beginning in the mid-20th century”

• introduction of new plant varieties and farming methods has increased food production per hectare.

• drawbacks: modern varieties of plants require fertilizer and pesticides that traditional varieties did not need and requires larger amounts of water and irrigation

3 primary soil nutrients (macronutrients)

nitrogen (N), phosphorous (P₂O₅), and potassium (K₂O)

• micronutrients (e.g., boron, zinc, and manganese) are needed in smaller amounts

world fertilizer use

• increased almost fivefold since 1960

• nitrogen fertilizer has contributed ~40% to the increase in per capita food production in the past 50 years

• 4 major crops in U.S. (corn, cotton, soybeans, and wheat) account for ~60% of the principal crop acreage and receive over 60% of the N,P, and K used in the U.S.

• grains use the most fertilizer?

Chemical Fertilizer

• chemical fertilizers do not replace soil organic matter, which is important for soil structure

• total dependency on chem fertilizers usually decreases the amount of organic matter and can change the physical, chemical, and biological properties of the soil

decomposition of organic matter produces…

• humus

• helps maintain proper soil chemistry, pH- nutrients not released too rapidly

potash and phosphate rock reserves

• most potash reserves are concentrated in Canada and Russia

• most phosphate rock reserve is concentrated in Morocco/Western Sahara

Soil Temperature

ground’s temperature is even more influential on plant growth than air warmth

corn production

• 1995 to 2017, between 72 and 97 million acres of corn planted annuallly

• land planted for corn peaked in 2012 at 97.3 million acrea

• 2021 prospectus: 91.444 mil acres

• 2023: 94.1 mil acres

• 2024: 91.5 mil acres

• corn acreage is concentrated in the center of the country

Corn: uses

• ~1/3 for feeding cattle, hogs, and poultry

• just over 1/3 to make ethanol

• rest is used for human food, beverages, and industrial uses in the U.S., or exported to other countries for food or feed use

pesticides

with the development of mechanization, many farmers changed from mixed agriculture to monocultures

• development from late 1800s through 1920s, quicker growth with Green Revolution

• this presented greater opportunities for pest problems to develop

• chemical pesticides were used to “solve” this problem

pest

any organism (animal or plant) that perpetuates itself in habitats where humans do not want to be

pesticide definition

any chemical used to kill or control populations of unwanted fungi, animals, or plants

• insecticides- used to control insect pop’s by killing them

• fungicides- for fungal pests

• rodenticides- kills mice, rats

• herbicides- pant pests (weeds → unwanted plants)

naturally derived repellant chemicals

• nicotine (tobacco)

• rotenone (tropical legumes)

• pyrethrum (chrysanthemums)

DDT history

• modern era of chemical pesticides began in 1934 with discovery of DDT

• rapid development of pesticides occurred during and after World War II

• 1st synthetic organic insecticide produced (Chlorinated hydrocarbon)

• Banned in USA (early 1970s) and World (1999)

herbicides

used to control unwanted plants and are heavily used in genetically modified crops

• weeds compete with crops for soil nutrients

• about 66% (2/3) of pesticides used in U.S. are herbicides

• some herbicides are toxic to all plants (nonselective) and some are selective as to the plant species they affect

• Glyphosate (Roundup) is a broad spectrum, nonselective, systemic herbicide used to control annual and perennial plants 

problems with pesticide use

pesticide resistance is a problem associated with widespread use of pesticides

• most surviving individuals have characteristics that allowed them to tolerate the pesticide

• survivors pass on genetic characteristics for tolerance

crops and pesticide

corn, fall potatoes, soybeans, and cotton accounted for nearly 2/3 of pesticide quantities applied

pesticide benefits

1. control spread of disease by killing insect vectors

2. mitigate crop losses

pesticide drawbacks

1. effects on non-target species (as much as 90% of pesticides never reach intended targets)

2. pesticide resistance

bioaccumulation

• accumulating higher and higher amounts of material within the body of an animal

• many persistent pesticides are fat soluble and build up in fat tissues

biomagnification

• acquiring increasing levels of a substance in the bodies of higher-tropic-level organisms

• ex. fish, birds

• more common in carnivorous birds (eagles, osprey, pelicans, etc)

characteristics of a perfect pesticide

• inexpensive

• only affect target organisms

• short half-life

• break down into harmless materials

why are pesticides so widely used?

Food production and economic concerns

• some 40% of global crop production is currently lost to pests

• plant diseases rob the global economy of more than $220 billion annually

• invasive pest cost countries at least $70 billion, and they are also one of the main drivers of biodiversity loss

• pesticides increase yields and profits

Health Reasons

• insecticides curtail many diseases

organically grown

legally defined term in the U.S. that tells you how a food or fiber crop was grown