Lecture 16/17

Question 1

Why is soil considered an ecosystem

Answer 1

it contains both living and non-living matter

Question 2

What are the most important areas for agriculture were originally grass lands

Answer 2

• Northern mixed grass prairie (North America)
• Tall grass prairie (North America)
• Pampas (South America)
• Steppes (Europe/ Asia)
• Savannah (Africa)

Question 3

What are the factors that influence soil formation

Answer 3

• organisms
• topography
• time
• climate
• parent material

Question 4

What are the types of weathering processes

Answer 4

• physical (wind, rain, thermal expansion/contraction, water freezing)
• chemical (water and gases)
• biological (tree roots and lichens)

Question 5

define humus

Answer 5

dark, spongy, crumbly mass of organic material formed by partial decomposition

Question 6

What are soil layers described by

Answer 6

• colour, texture, structure, pH

Question 7

What are the different soil layers

Answer 7

O horizon = surface litter
A horizon = topsoil –> contains decaying organic matter (humus) and living soil organisms
B horizon = subsoil –> denser than A horizon, higher mineral content, lower fertility
C horizon = contains rock in the process of being broken (weathering) to produce new soil
R horizon = solid rock that has not been broken down

Question 8

define ion exchange capacity

Answer 8

• cations (K, Na, Ca, Mg) remain in root zone
• anions (NO3, PO4, SO4) leach out of root zone

Question 9

define agriculture

Answer 9

The practice of growing crops and raising livestock for human use and consumption

Question 10

define cropland

Answer 10

land used to grow crop plants

Question 11

define rangeland or pasture

Answer 11

land used for grazing livestock

Question 12

define subsistence agriculture (traditional agriculture)

Answer 12

families produce only enough food for themselves
- supplemented by hunting

Question 13

define intensive agriculture (traditional agriculture)

Answer 13

produces excess food to sell
- uses animals, irrigation, and natural fertilizers
- does not use fossil fuels

Question 14

define monoculture

Answer 14

uniform planting of one single crop
- not natural

Question 15

what are some uses of monoculture

Answer 15

1. large-scale mechanization (machinery)
2. high fossil fuel quantities to boost yields
3. irrigation (high water needs)
4. chemicals (pesticides and fertilizers)

Question 16

define feedlots (factory farms)

Answer 16

CAFO (concentrated animal feeding operations)
- Large warehouses or pens designed to deliver energy-rich food to animals living in extremely high density enclosures (pens, cages)

Question 17

What are some benefits of CAFO’s

Answer 17

• greater production of food
• unavoidable in countries with high levels of meat consumption,
• reduces demand for land for pasture

Question 18

What are some drawbacks to CAFO’s

Answer 18

• contributions to water/air pollution
• poor waste containment causes outbreaks of disease/infections
• high use of antibiotics to control disease – antibiotic resistance

Question 19

define extensification

Answer 19

bringing more land into production

Question 20

define intensification

Answer 20

better productivity per unit of land

Question 21

what is the green revolution dependent on

Answer 21

• synthetic fertilizers
• chemical pesticides
• irrigation
• heavy equipment

Question 22

what are some positive effects of the green revolution

Answer 22

• prevented some deforestation
• preserved biodiversity

Question 23

what are some negative effects of the green revolution

Answer 23

• pests
• pollution (fertilizers)
• erosion
• salinization
• desertification

Question 24

define pest

Answer 24

any organism that damages valuable crops and/or livestock

Question 25

define weed

Answer 25

any plant that competes with crops

Question 26

define pesticides

Answer 26

poisons that target pest organisms

Question 27

define insecticides

Answer 27

target insects

Question 28

define herbicides

Answer 28

target plants

Question 29

fungicides

Answer 29

target fungi

Question 30

define evolutionary arms race

Answer 30

chemists increase chemical toxicity to compete with resistant pests

Question 31

define pollination

Answer 31

male sex cells (pollen) fertilize female sex cells - by wind, water, or animals

Question 32

What are some examples of animal pollinators

Answer 32

- hummingbirds and other birds - bats - insects (bees, butterflies, flies, moths)

Question 33

define soil degradation

Answer 33

damage/loss of soils from poor management - productive soils are renewable

Question 34

what are the two reasons for erosion

Answer 34

- due to drought - due to mismanagement of soils

Question 35

define swidden agriculture

Answer 35

- cultivation of a plot for a few years and then abandoning it and moving on to a new plot of land (that is burned and cleared for agriculture)

Question 36

define desertification

Answer 36

when there is a loss of more than 10% productivity of crops

Question 37

what causes desertification

Answer 37

- erosion, soil compaction, forest removal, overgrazing, salinization, climate change, depletion of water sources

Question 38

what are some solutions for erosion and desertification

Answer 38

conserve soils, restore/maintain plant cover, prevent salinization, improve fertilization practices, reduce overgazing

Question 39

define crop rotation

Answer 39

alternating crops from year to year

Question 40

define contour farming

Answer 40

plowing fields perpendicular to the slope

Question 41

define terracing

Answer 41

level platforms are cut into steep hillsides

Question 42

define intercropping

Answer 42

planting different types of crops in alternating bands or other arrangements - more natural

Question 43

define reduced tillage

Answer 43

furrows are cut into the soil, a seed is dropped in and furrow is closed - no-till farming disturbs soil even less

Question 44

define plant cover

Answer 44

- reduces soil erosion along creeks and roadsides - stabilize soils by using plants to anchor soil - use tree-planting programs to slow erosion

Question 45

define irrigation (prevent salinization problems)

Answer 45

artificially providing water to support agriculture

Question 46

define waterlogging (prevent salinization problems)

Answer 46

over-irrigated soils - water suffocates roots

Question 47

define salinization (prevent salinization problems)

Answer 47

buildup of salts in surface soil layers

Question 48

what are easier and cheaper ways to prevent salinization

Answer 48

- do not plant water-guzzling crops in sensitive areas - choose appropriate crops for area - irrigate with low-salt water

Question 49

define fertilizer

Answer 49

substances that contain essential nutrients

Question 50

define inorganic fertilizers

Answer 50

mined or synthetically manufactured mineral supplements

Question 51

define organic fertilizers

Answer 51

remains or wastes of organisms - manure, crop residues, fresh vegetation - compost= produced when decomposers break down organic matter