chp. 9 vocab
Terms
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- genetically modified organisms
- organisms whose genetic code has been altered by artificial means such as interspecies gene transfer
- rill erosion
- the removing of thin layers of soil as little rivulets of running water gather and cut small channels of soil
- cover crops
- plants, such as rye, alfalfa, or clover, that can be planted immediately after harvest to hold and protect the soil
- strip farming
- planting diffferent kinds of crops in alternating strips along land contours; when one crop is harvested, the other crop remainsto protect the soil and prevent water from running straight down a hill
- topsoil
- the first true layer of soil; layer in which organic material is mixed with mineral particles; thickness ranges from a meter or more under virgin prairie to zero in some deserts
- chronically undernourished
- those people whose diet doesn't provide the 2,200 kcal per day, on average, considered necessary for a healthy productive life
- genetic engineering
- laboratory manipulation of genetic material using molecular biology techniques to create desired characteristics in organisms
- perennial species
- plants that grow for more than 2 years
- micorrhizal symbiosis
- an association between the roots of most plant species and certain fungi. The plant provides organic compounds to the fungus, while the fungus provides water and nurtients to the plant
- green revolution
- dramatically increased agricultural production brought about by "miracle" strains of grain; usually requires high inputs of water, plant nutrients, and pesticides
- reduced tillage systems
- systems, such as minimum till, conserve-till, and no-till, that preserve soil, save energy and water, and increase crop yields
- soil horizons
- horizontal layers that reveal a soil's history, characteristics and usefulness
- contour plowing
- plowing along hill contours; reduces erosion
- soil profile
- all the vertical layer or horizons that make up a soil in a particular place
- sustainable agriculture
- an ecologically sound, economically viable, socially just, and humane agriultural system. Stewardship, soil conservation, and integrated pest management are essential for sustainability
- mulch
- protective ground cover, including both natural products and synthetic materials that protect the soil, save water, and prevent weed growth
- terracing
- shaping the land to create level shelves of earth to hold water and soil; requires extensive hand labor or expensive machinery , but it enables farmers to farm very steep hillsides
- subsoil
- a layer of soil beneath the topsoil that has lower organic content and higher concentrations of fine mineral particles; often contains soluble compounds and clay particles carried down by percolating water
- malnourishment
- a nutritional imbalance caused by lack of specific dietary components or inability to absorb or utilize essential nutrients
- famines
- acute food shortages characterized by large-scale loss of life, social disruption, and economic chaos
- humus
- sticky, brown, insoluble residue from the bodies of dead plants and animals; gives soil its structure, coating mineral particles and holding them together; serves as major source of plant nutrients
- sheet erosion
- peeling off thin layers of soil from the land surface; accomplished primaril by wind and water
- gully erosion
- removal of layers of soil, creating channels or ravines too large to be removed by normal tillage operations
- kwashiorkor
- a widespread human protein deficiency disease resulting from a starchy diet low in protein and essential amino acids
- obese
- generally considered to be a body mass greater than kg/m^2, or roughly 30 pounds above noraml for an average person
- soil
- a complex mixture of weathered mineral materials from rocks, partially decomposed organic molecules, and a host of living organisms
- marasmus
- a widespread human protein deficiency disease caused by a diet low in calories and protein or imbalanced in essential amino acids
- anemia
- low levels of hemoglobin due to iron deficiency or lack of red blood cells
- waterlogging
- water saturation of soil that fills all air spaces and causes plant roots to die from lack of oxygen; a result of overirrigation
- salinization
- a process in whih mineral salts accumulate in the soil, killing plants; occurs when soils in dry climates are irrigated profusely
- food security
- the ability of individuals to obtain suficient food on a day-to-day basis