09 Glossary

Glossary	Ch01 Ch02 Ch03 Ch04 Ch05 Ch06 Ch07 Ch08 Ch08 Ch10 Ch11 Ch12 Ch13 Ch14
Chapter 9
agroforestry	Planting trees and crops together.
alley cropping	Planting of crops in strips with rows of trees or shrubs on each side.
animal manure	Dung and urine of animals used as a form of organic fertilizer. Compare green manure.
annual	Plant that grows, sets seed, and dies in one growing season. Compare perennial.
aquaculture	Growing and harvesting of fish and shellfish for human use in freshwater ponds, irrigation ditches, and lakes, or in cages or fenced-in areas of coastal lagoons and estuaries. See fish farming, fish ranching.
arable land	Land that can be cultivated to grow crops.
artificial selection	Process by which humans select one or more desirable genetic traits in the population of a plant or animal and then use selective breeding to end up with populations of the species containing large numbers of individuals with the desired traits. Compare genetic engineering, natural selection.
biological pest control	Control of pest populations by natural predators, parasites, or disease-causing bacteria and viruses (pathogens).
commercial extinction	Depletion of the population of a wild species used as a resource to a level at which it is no longer profitable to harvest the species.
commercial inorganic fertilizer	Commercially prepared mixture of plant nutrients such as nitrates, phosphates, and potassium applied to the soil to restore fertility and increase crop yields. Compare organic fertilizer.
compost	Partially decomposed organic plant and animal matter used as a soil conditioner or fertilizer.
conservation-tillage farming	Crop cultivation in which the soil is disturbed little (minimum-tillage farming) or not at all (no-till farming) to reduce soil erosion, lower labor costs, and save energy. Compare conventional-tillage farming.
contour farming	Plowing and planting across the changing slope of land, rather than in straight lines, to help retain water and reduce soil erosion.
conventional-tillage farming	Crop cultivation method in which a planting surface is made by plowing land, breaking up the exposed soil, and then smoothing the surface. Compare conservation-tillage farming.
crop rotation	Planting a field, or an area of a field, with different crops from year to year to reduce soil nutrient depletion. A plant such as corn, tobacco, or cotton, which removes large amounts of nitrogen from the soil, is planted one year. The next year a legume such as soybeans, which adds nitrogen to the soil, is planted.
cultural eutrophication	Overnourishment of aquatic ecosystems with plant nutrients (mostly nitrates and phosphates) because of human activities such as agriculture, urbanization, and discharges from industrial plants and sewage treatment plants. See eutrophication.
desertification	Conversion of rangeland, rain-fed cropland, or irrigated cropland to desertlike land, with a drop in agricultural productivity of 10% or more. It usually is caused by a combination of overgrazing, soil erosion, prolonged drought, and climate change.
economic threshold	Point at which the economic loss caused by pest damage outweighs the cost of applying a pesticide.
erosion	Process or group of processes by which loose or consolidated earth materials are dissolved, loosened, or worn away and removed from one place and deposited in another. See weathering.
famine	Widespread malnutrition and starvation in a particular area because of a shortage of food, usually caused by drought, war, flood, earthquake, or other catastrophic events that disrupt food production and distribution.
feedlot	Confined outdoor or indoor space used to raise hundreds to thousands of domesticated livestock. Compare rangeland.
fertilizer	Substance that adds inorganic or organic plant nutrients to soil and improves its ability to grow crops, trees, or other vegetation. See commercial inorganic fertilizer, organic fertilizer.
fish farming	Form of aquaculture in which fish are cultivated in a controlled pond or other environment and harvested when they reach the desired size. See also fish ranching.
fish ranching	Form of aquaculture in which members of a fish species such as salmon are held in captivity for the first few years of their lives, released, and then harvested as adults when they return from the ocean to their freshwater birthplace to spawn. See also fish farming.
fungicide	Chemical that kills fungi.
gene splicing	See genetic engineering.
genetic engineering	Insertion of an alien gene into an organism to give it a new and usually beneficial genetic trait. Compare artificial selection, natural selection.
genetically modified organism (GMO)	Organism whose genetic makeup has been modified by genetic engineering.
green manure	Freshly cut or still-growing green vegetation that is plowed into the soil to increase the organic matter and humus available to support crop growth. Compare animal manure.
green revolution	Popular term for introduction of scientifically bred or selected varieties of grain (rice, wheat, maize) that, with high enough inputs of fertilizer and water, can greatly increase crop yields.
gully reclamation	Restoring land suffering from gully erosion by seeding gullies with quick-growing plants, building small dams to collect silt and gradually fill in the channels, and building channels to divert water away from the gully.
herbicide	Chemical that kills a plant or inhibits its growth.
high-input agriculture	See industrialized agriculture.
humus	Slightly soluble residue of undigested or partially decomposed organic material in topsoil. This material helps retain water and water-soluble nutrients, which can be taken up by plant roots.
hunter-gatherers	People who get their food by gathering edible wild plants and other materials and by hunting wild animals and fish. Compare agricultural revolution, environmental revolution, industrial revolution, information and globalization revolution.
industrialized agriculture	Using large inputs of energy from fossil fuels (especially oil and natural gas), water, fertilizer, and pesticides to produce large quantities of crops and livestock for domestic and foreign sale. Compare subsistence farming.
infiltration	Downward movement of water through soil.
inorganic fertilizer	See commercial inorganic fertilizer.
insecticide	Chemical that kills insects.
integrated pest management (IPM)	Combined use of biological, chemical, and cultivation methods in proper sequence and timing to keep the size of a pest population below the size that causes economically unacceptable loss of a crop or livestock animal.
intercropping	Growing two or more different crops at the same time on a plot. For example, a carbohydrate-rich grain that depletes soil nitrogen and a protein-rich legume that adds nitrogen to the soil may be intercropped. Compare monoculture, polyculture, polyvarietal cultivation.
interplanting	Simultaneously growing a variety of crops on the same plot. See agroforestry, intercropping, polyculture, polyvarietal cultivation.
kilocalorie (kcal)	Unit of energy equal to 1,000 calories. See calorie.
kwashiorkor	Type of malnutrition that occurs in infants and very young children when they are weaned from mother's milk to a starchy diet low in protein. See marasmus, malnutrition.
land classification	Method for reducing soil erosion that identifies easily erodible land that should not be planted in crops or cleared of vegetation.
leaching	Process in which various chemicals in upper layers of soil are dissolved and carried to lower layers and, in some cases, to groundwater.
loams	Soils containing a mixture of clay, sand, silt, and humus. Good for growing most crops.
low-input agriculture	See sustainable agriculture.
macronutrients	Chemical elements that organisms need in large amounts to live, grow, or reproduce. Examples are carbon, oxygen, hydrogen, nitrogen, phosphorus, sulfur, potassium, calcium, magnesium, and iron. Compare micronutrients.
malnutrition	Faulty nutrition, caused by a diet that does not supply an individual with enough protein, essential fats, vitamins, minerals, and other nutrients needed for good health. See kawashiorkor, maramus. Compare overnutrition, undernutrition.
manure	See animal manure, green manure.
marasmus	Nutritional deficiency disease caused by a diet that does not have enough calories and protein to maintain good health. See kwashiorkor, malnutrition.
micronutrients	Chemical elements organisms need in small or even trace amounts to live, grow, or reproduce. Examples are sodium, zinc, copper, chlorine, and iodine. Compare macronutrients.
minimum-tillage farming	See conservation-tillage farming.
monoculture	Cultivation of a single crop, usually on a large area of land. Compare polyculture, polyvarietal cultivation.
no-till farming	See conservation-tillage farming.
nutrient	Any food, element, or compound an organism must take in to live, grow, or reproduce.
nutrient cycle	See biogeochemical cycle.
organic farming	Producing crops and livestock naturally by using organic fertilizer (manure, legumes, compost) and natural pest control (bugs that eat harmful bugs, plants that repel bugs, and environmental controls such as crop rotation) instead of using commercial inorganic fertilizers and synthetic pesticides and herbicides. See sustainable agriculture.
organic fertilizer	Organic material such as animal manure, green manure, and compost, applied to cropland as a source of plant nutrients. Compare commercial inorganic fertilizer.
overfishing	Harvesting so many fish of a species, especially immature fish, that not enough breeding stock is left to replenish the species, such that it is not profitable to harvest them.
overgrazing	Destruction of vegetation when too many grazing animals feed too long and exceed the carrying capacity of a rangeland or pasture area.
overnutrition	Diet so high in calories, saturated (animal) fats, salt, sugar, and processed foods and so low in vegetables and fruits that the consumer runs high risks of diabetes, hypertension, heart disease, and other health hazards. Compare malnutrition, undernutrition.
pasture	Managed grassland or enclosed meadow that usually is planted with domesticated grasses or other forage to be grazed by livestock. Compare feedlot, rangeland.
perennial	Plant that can live for more than 2 years. Compare annual.
persistence	How long a pollutant stays in the air, water, soil, or body. See also inertia.
pest	Unwanted organism that directly or indirectly interferes with human activities.
pesticide	Any chemical designed to kill or inhibit the growth of an organism that people consider undesirable. See fungicide, herbicide, insecticide.
pH	Numeric value that indicates the relative acidity or alkalinity of a substance on a scale of 0-14, with the neutral point at 7. Acid solutions have pH values lower than 7, and basic or alkaline solutions have pH values greater than 7.
plantation agriculture	Growing specialized crops such as bananas, coffee, and cacao in tropical developing countries, primarily for sale to developed countries.
polyculture	Complex form of intercropping in which a large number of different plants maturing at different times are planted together. See also intercropping. Compare monoculture, polyvarietal cultivation.
polyvarietal cultivation	Planting a plot of land with several varieties of the same crop. Compare intercropping, monoculture, polyculture.
rangeland	Land that supplies forage or vegetation (grasses, grasslike plants, and shrubs) for grazing and browsing animals and is not intensively managed. Compare feedlot, pasture.
ruminants	Grazing animals with complex digestive systems that enable them to convert grass and other roughage into meat and milk.
salinization	Accumulation of salts in soil that can eventually make the soil unable to support plant growth.
shelterbelt	See windbreak.
shifting cultivation	Clearing a plot of ground in a forest, especially in tropical areas, and planting crops on it for a few years (typically 2-5 years) until the soil is depleted of nutrients or the plot has been invaded by a dense growth of vegetation from the surrounding forest. Then a new plot is cleared and the process is repeated. The abandoned plot cannot successfully grow crops for 10-30 years. See also slash-and-burn cultivation.
slash-and-burn cultivation	Cutting down trees and other vegetation in a patch of forest, leaving the cut vegetation on the ground to dry, and then burning it. The ashes that are left add nutrients to the nutrient-poor soils found in most tropical forest areas. Crops are planted between tree stumps. Plots must be abandoned after a few years (typically 2-5 years) because of loss of soil fertility or invasion of vegetation from the surrounding forest. See also shifting cultivation.
soil	Complex mixture of inorganic minerals (clay, silt, pebbles, and sand), decaying organic matter, water, air, and living organisms.
soil conservation	Methods used to reduce soil erosion, prevent depletion of soil nutrients, and restore nutrients already lost by erosion, leaching, and excessive crop harvesting.
soil erosion	Movement of soil components, especially topsoil, from one place to another, usually by wind, flowing water, or both. This natural process can be greatly accelerated by human activities that remove vegetation from soil.
soil horizons	Horizontal zones that make up a particular mature soil. Each horizon has a distinct texture and composition that vary with different types of soils. See soil profile.
soil permeability	Rate at which water and air move from upper to lower soil layers. Compare porosity.
soil porosity	See porosity.
soil profile	Cross-sectional view of the horizons in a soil. See soil horizon.
soil structure	How the particles that make up a soil are organized and clumped together. See also soil permeability, soil texture.
soil texture	Relative amounts of the different types and sizes of mineral particles in a sample of soil.
strip cropping	Planting regular crops and close-growing plants, such as hay or nitrogen-fixing legumes, in alternating rows or bands to help reduce depletion of soil nutrients.
subsistence farming	Supplementing solar energy with energy from human labor and draft animals to produce enough food to feed oneself and family members; in good years there may be enough food left over to sell or put aside for hard times. Compare industrialized agriculture.
sustainable agriculture	Method of growing crops and raising livestock based on organic fertilizers, soil conservation, water conservation, biological pest control, and minimal use of nonrenewable fossil fuel energy.
terracing	Planting crops on a long, steep slope that has been converted into a series of broad, nearly level terraces with short vertical drops from one to another that run along the contour of the land to retain water and reduce soil erosion.
traditional intensive agriculture	Producing enough food for a farm family's survival and perhaps a surplus that can be sold. This type of agriculture uses higher inputs of labor, fertilizer, and water than traditional subsistence agriculture. See traditional subsistence agriculture. Compare industrialized agriculture.
traditional subsistence agriculture	Production of enough crops or livestock for a farm family's survival and, in good years, a surplus to sell or put aside for hard times. Compare industrialized agriculture, traditional intensive agriculture.
undergrazing	Reduction of the net primary productivity of grassland vegetation and grass cover from absence of grazing for long periods (at least 5 years). Compare overgrazing.
undernutrition	Consuming insufficient food to meet one's minimum daily energy needs for a long enough time to cause harmful effects. Compare malnutrition, overnutrition.
village	Group of rural households linked together by custom, culture, and family ties, usually surviving by harvesting local natural resources for food, fuel, and other basic needs. Compare city. See rural area, urban area.
waterlogging	Saturation of soil with irrigation water or excessive precipitation so the water table rises close to the surface.
weathering	Physical and chemical processes in which solid rock exposed at earth's surface is changed to separate solid particles and dissolved material, which can then be moved to another place as sediment. See erosion.
windbreak	Row of trees or hedges planted to partially block wind flow and reduce soil erosion on cultivated land.