Unit 5: Earth's Land Resources and Use Flashcards
Soil
a complex system of inorganic, weathered parent material (rock), organic matter, water, gases, nutrients, and microorganisms; a renewable source, but renewal occurs very slowly
Soil Degredation
results primarily from forest removal, cropland agricultural practices, and overgrazing of livestock
Subsistence Agriculture
producing only enough food for it to cover the entire family
Monoculture
only farming a one single crop, on a large-scale
Polyculture
farming several different crops
Green Revolution
spreads industrial agriculture techniques practiced in developed nations to developing countries; increased crop yields and helps prevent mass starvation
Culinary Sustainability
a pursuit that embraces the use of fresh, healthy, locally produced foods
Closed Loop System
uneaten food waste from dining commons is fed into an anaerobic digestion system, where it is broken down to generate a nutrient-rich liquid and then used to nourish soils of the campus cropland
Material of Soil
consists of 50% mineral matter, 5% organic matter (includes living/dead microorganisms and decaying material of plants and animals), and 45% air or water
Parent Material
the base geological material, rock, or sediment of a particular location
Soil Formation
the slow physical, chemical, and biological weathering of parent material and the accumulation and transformation of organic matter
Soil Horizons
the distinct layers of soil that develop as wind, water, and organisms move and sort the fine particles weathering creates, producing a soil profile
O Horizon
the litter layer of soil, consisting mostly of organic matter
A Horizon
the topsoil, consisting of some organic material mixed with mineral components
E Horizon
the zone of leaching in soil (eluviation), where mineral and organic matter tend to leave this horizon and move into the next lower layer
B Horizon
the subsoil, where minerals and organic matter accumulate from above
C Horizon
layer of soil that consists largely of weathered parent material
R Horizon
layer of soil where it only consists of the rock or sediment of pure parent material
Top Soil
the crucial horizon for agriculture and ecosystems; it is the most nutritive, taking its texture, coloration, and water-holding capacity from the humus content
Humus
partially decomposed organic matter
Soil Texture
determined by the size of its particles, ranging from clay (the smallest), silt (intermediate), to sand (the largest)
Loam
soil with an even mixture of clay, silt, and sand
Cation Exchange Capacity (CEC)
the process by which plants’ roots donate hydrogen ions to the soil in exchange for cations (positively charged ions) of nutritional value such as calcium, magnesium, and potassium; often referred to as the nutrient-holding capacity of soil
Land Degredation
deterioration that diminishes land’s productivity and biodiversity, impairs the functioning of its ecosystems, and reduces the ecosystem services the land can offer
Erosion
the removal of material from one place and its transport to another by wind or water; major causes are (1) overcultivating fields through excessive tilling (2) grazing range-land with more livestock than the land can support (3) removing forests on steep slopes or with large clear-cuts
Desertification
a form of land degradation affecting arid lands in which more than 10% if productivity is lost as a result of erosion, soil compaction, forest removal, overgrazing, drought, salinization, water depletion, or other factors
Dust Bowl
a major drought in the 1930s that occurred with the large-scale cultivation and overgrazing of native grasses in North Americas Great Plains; millions of tons of topsoil eroded and were lost forever
Overgrazing
done by cattle, sheep, goats, or other livestock that can contribute to soil degradation, especially when native grasses are removed
The Soil Conservation Act (1935)
established the Soil Conservation Service (SCS) in response to the devastation caused in the Dust Bowl; it was renamed the Natural Resources Conservation Service (NRCS) and responsibilities were expanded to include water quality protection and pollution control
Conservation Tillage
describes an array of approaches that reduce the amount of tilling relative to conventional farming; any method of limited tilling that leaves more than 30% of crop residue covering the soil after harvest
No-Till Agriculture
the most extreme form of conservation tillage and does not involve tilling (plowing or disking) the soil; it cuts furrows through the O horizon of dead weeds and crop residue and the upper levels of the A horizon, dropping seeds and fertilizers into the furrow; increased organic matter also helps to improve soil’s fertility
Crop Rotation
involves alternating the type of crop grown in a given field from one season to the next; it returns nutrients to the soil, breaks plant disease cycles, and minimizes erosion
Contour Farming
plowing furrows sideways across a hillside; prevents runoff and erosion
Terracing
the most effective method for preventing soil erosion on extremely steep terrain; they are level platforms/steps that are cut into steep hillsides to contain irrigation water
Intercropping
minimizes erosion by planting different types of crops in alternating bands or other spatially mixed arrangements
Shelterbelts
a technique used to reduce erosion caused by wind; consists of rows of trees or tall shrubs that are planted along the edges of fields to slow the wind
Irrigation
the artificial provision of water beyond that which crops receive from rainfall
Salinization
occurs most frequently in arid agricultural areas when the small amounts of salts in irrigation water become highly concentrated on the soil surface through high evaporation rates
Waterlogging
occurs when over irrigation saturates the soil and causes the water table to rise to the level that plant roots are drowned, essentially suffocating the plants
Drip-Irrigation
where hoses drop water directly into soil near the plant’s roots
Subsidies
government incentives of cash or tax breaks
Conservation Reserve Program
pays farmers to stop cultivating highly erodible cropland and instead places it in conservation reserves planted with grasses and trees
Norman Borlaug
developed improved varieties of wheat through selective breeding
Monocultures
large expanses of single crop types replaced the traditional, small-scale polycultures as they were found to be more efficient for planting and harvesting
Seed Banks
institutions preserving genetic diversity as a kind of living museum
The Sierra de Manantlan Biosphere Reserve
an important repository of crop biodiversity, especially for maize (southern Mexico)
Feedlots
an industrial agriculture practice; also known as factory farms, or concentrated animals feeding operations (CAFOs)
Concentrated Animal Feeding Operations (CAFOs)
huge warehouses or pens designed to deliver energy-rich food to confined animals living at extremely high densities
Aquaculture
the cultivation of aquatic organisms for food in controlled environments
Bycatch
the unintended catch of nontarget species
Pollination
the process by which male sex cells of a plant (pollen) fertilize the female egg cells of a plant, and is essential for plant reproduction
Colony Collapse Disorder
up to one-third of all honeybees in the U.S. have vanished; hypotheses as to causes are insecticides, weed-killers, parasitic mites, or a combination of these stresses
Pesticides
synthetic chemicals used to kill insects
Neonicotinoids
make the plant toxic to insects, killing them as they feed on or pollinate the plant
“Pesticide Treadmill”
pests can evolve resistance to chemical pesticides, requiring humans to design over-increasingly toxic poisons in order to kill the genetically resistant individuals
Biological Control (biocontrol)
the use of living species that are the natural enemy of or prey upon or parasitize the targeted pest
Bacillus Thuringiensis (Bt0
a naturally occurring soil bacterium that produces a toxin that kills many caterpillars and some fly and beetle larvae; can be sprayed on crops
Integrated Pest Management (IPM)
incorporates numerous techniques, including biocontrol, use of limited chemicals when essential, crop rotation, transgenic crops, alternative tillage methods, and mechanical pest removal
Organic Agriculture
uses no synthetic fertilizers, insecticides, fungicides or herbicides, but instead relies on biological approaches such as bioncontrol and composting
Genetic Engineering
any process whereby scientists directly manipulate an organism’s genetic material in the laboratory by adding, deleting, or changing segments of its DNA
Genetically Modified Organisms (GMOs)
organisms that have been genetically engineered using recombinant DNA
Recombinant DNA
DNA that has been spliced together from multiple organisms
Transgenic Organisms
those that contain DNA from another species; all GM organisms are also transgenic species
“Roundup Ready Crops”
contain genes to resist their widely used herbicide
Bt Crops
have the ability to produce their own toxic effects on insects
Precautionary Princple
“One should not undertake a new action until the ramifications of that action are fully understood”
Sustainable Agriculture
agriculture that does not deplete soils faster than they form and does not reduce the amount of clean water or genetic diversity essential to long-term crop and livestock production
Organic Agriculture
the production of crops without the use of synthetic pesticides or fertilizers, using ecological principles and attempting to keep as much organic matter in the soil as possible
Organic Food Production (1990)
established the national standards for organic products (both crops and livestock) in the United States
Locally Grown Agriculture
reducing fossil fuel use by avoiding long-distance transport
Community-Supported Agriculture (CSA)
where consumers partner with local farmers to pay in advance for a share of their yield
Carbon Storage
the more forests we reserve or restore, the more carbon (in the form of carbon dioxide) that can be kept out of the atmosphere
Deforestation
the clearing and loss of forests, has been driven by the demand for wood (as fuel and building materials) and for agricultural land to feed the world’s growing population
Primary Forest/Old-Growth Forest
natural forests uncut by humans or natural disasters in 200 years or more
Secondary-Growth Forests
forests that have grown back from secondary succession once` land has been cleared
