Lecture 16/17 Flashcards
Why is soil considered an ecosystem
it contains both living and non-living matter
What are the most important areas for agriculture were originally grass lands
- Northern mixed grass prairie (North America)
- Tall grass prairie (North America)
- Pampas (South America)
- Steppes (Europe/ Asia)
- Savannah (Africa)
What are the factors that influence soil formation
- organisms
- topography
- time
- climate
- parent material
What are the types of weathering processes
- physical (wind, rain, thermal expansion/contraction, water freezing)
- chemical (water and gases)
- biological (tree roots and lichens)
define humus
dark, spongy, crumbly mass of organic material formed by partial decomposition
What are soil layers described by
- colour, texture, structure, pH
What are the different soil layers
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
define ion exchange capacity
- cations (K, Na, Ca, Mg) remain in root zone
- anions (NO3, PO4, SO4) leach out of root zone
define agriculture
The practice of growing crops and raising livestock for human use and consumption
define cropland
land used to grow crop plants
define rangeland or pasture
land used for grazing livestock
define subsistence agriculture (traditional agriculture)
families produce only enough food for themselves
- supplemented by hunting
define intensive agriculture (traditional agriculture)
produces excess food to sell
- uses animals, irrigation, and natural fertilizers
- does not use fossil fuels
define monoculture
uniform planting of one single crop
- not natural
what are some uses of monoculture
- large-scale mechanization (machinery)
- high fossil fuel quantities to boost yields
- irrigation (high water needs)
- chemicals (pesticides and fertilizers)
define feedlots (factory farms)
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)
What are some benefits of CAFO’s
- greater production of food
- unavoidable in countries with high levels of meat consumption,
- reduces demand for land for pasture
What are some drawbacks to CAFO’s
- contributions to water/air pollution
- poor waste containment causes outbreaks of disease/infections
- high use of antibiotics to control disease – antibiotic resistance
define extensification
bringing more land into production
define intensification
better productivity per unit of land
what is the green revolution dependent on
- synthetic fertilizers
- chemical pesticides
- irrigation
- heavy equipment
what are some positive effects of the green revolution
- prevented some deforestation
- preserved biodiversity
what are some negative effects of the green revolution
- pests
- pollution (fertilizers)
- erosion
- salinization
- desertification
define pest
any organism that damages valuable crops and/or livestock
define weed
any plant that competes with crops
define pesticides
poisons that target pest organisms
define insecticides
target insects
define herbicides
target plants
fungicides
target fungi
define evolutionary arms race
chemists increase chemical toxicity to compete with resistant pests
define pollination
male sex cells (pollen) fertilize female sex cells
- by wind, water, or animals
What are some examples of animal pollinators
- hummingbirds and other birds
- bats
- insects (bees, butterflies, flies, moths)
define soil degradation
damage/loss of soils from poor management
- productive soils are renewable
what are the two reasons for erosion
- due to drought
- due to mismanagement of soils
define swidden agriculture
- 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)
define desertification
when there is a loss of more than 10% productivity of crops
what causes desertification
- erosion, soil compaction, forest removal, overgrazing, salinization, climate change, depletion of water sources
what are some solutions for erosion and desertification
conserve soils, restore/maintain plant cover, prevent salinization, improve fertilization practices, reduce overgazing
define crop rotation
alternating crops from year to year
define contour farming
plowing fields perpendicular to the slope
define terracing
level platforms are cut into steep hillsides
define intercropping
planting different types of crops in alternating bands or other arrangements
- more natural
define reduced tillage
furrows are cut into the soil, a seed is dropped in and furrow is closed
- no-till farming disturbs soil even less
define plant cover
- reduces soil erosion along creeks and roadsides
- stabilize soils by using plants to anchor soil
- use tree-planting programs to slow erosion
define irrigation (prevent salinization problems)
artificially providing water to support agriculture
define waterlogging (prevent salinization problems)
over-irrigated soils - water suffocates roots
define salinization (prevent salinization problems)
buildup of salts in surface soil layers
what are easier and cheaper ways to prevent salinization
- do not plant water-guzzling crops in sensitive areas
- choose appropriate crops for area
- irrigate with low-salt water
define fertilizer
substances that contain essential nutrients
define inorganic fertilizers
mined or synthetically manufactured mineral supplements
define organic fertilizers
remains or wastes of organisms
- manure, crop residues, fresh vegetation
- compost= produced when decomposers break down organic matter
