Hemp Category: Plant and animal resources Where Found Hemp, Cannabis sativa, is indigenous to temperate re-gions in Asia.. Technical Definition Cannabis sativa is a multipurpose plant t
Trang 1Kabat, Geoffrey C Hyping Health Risks: Environmental
Hazards in Daily Life and the Science of Epidemiology.
New York: Columbia University Press, 2008
Lippmann, Morton, ed Environmental Toxicants:
Hu-man Exposures and Their Health Effects 3d ed
Ho-boken, N.J.: John Wiley & Sons, 2009
Rodricks, Joseph V Calculated Risks: The Toxicity and
Human Health Risks of Chemicals in Our Environment.
2d ed New York: Cambridge University Press, 2007
Sala, Osvaldo E., Laura A Meyerson, and Camille
Par-mesan, eds Biodiversity Change and Human Health:
From Ecosystem Services to Spread of Disease
Washing-ton, D.C.: Island Press, 2009
Skjei, Eric, and M Donald Whorton Of Mice and
Mole-cules: Technology and Human Survival New York:
Dial Press, 1983
Web Site
World Health Organization
Environmental Health
http://www.who.int/topics/environmental_
health/en
See also: Air pollution and air pollution control;
As-bestos; Environmental degradation, resource
exploi-tation and; Greenhouse gases and global climate
change; Mining safety and health issues; Nuclear waste
and its disposal; Pesticides and pest control;
Popula-tion growth; United NaPopula-tions ConvenPopula-tion on
Long-Range Transboundary Air Pollution; Water pollution
and water pollution control
Helium
Category: Mineral and other nonliving resources
Where Found
Helium is concentrated in some natural gas wells,
par-ticularly in Texas, Oklahoma, and Kansas Helium is
also found in the Earth’s atmosphere
Primary Uses
The most important use of helium is as a cryogenic
coolant, since it permits cooling to temperatures lower
than any other substance Helium is also used as a
lift-ing gas for airships, as a replacement for nitrogen in
the breathing gas for deep-sea divers, and as an inert
atmosphere for welding
Technical Definition Helium (abbreviated He), atomic number 2, belongs
to the last column of the periodic table of the ele-ments It has two naturally occurring isotopes and
an average molecular weight of 4.003 Helium is a gas, having a density of 0.1637 gram/liter at 25° Celsius and 1 atmosphere of pressure Helium boils at
−268.9° Celsius It is the most chemically inert ele-ment in the periodic table
Description, Distribution, and Forms Helium does not form any chemical compounds It
is the lightest of the noble gases, so light that it quickly escapes into space from the Earth’s atmosphere Thus, much of the helium now found on the Earth was pro-duced by radioactive decay In excess of 130 million cubic meters of helium is produced annually in the United States A majority of this helium is used by government agencies, including the Department of Energy and the National Aeronautics and Space Ad-ministration (NASA)
Small quantities of helium, pure helium 4, are pro-duced by the radioactive decay of uranium or thorium
in the Earth In locations where uranium or thorium concentrations are high, helium collects in the same cavities as natural gas The largest concentrations of helium are found in some natural gas wells in New Mexico, Texas, Oklahoma, Utah, and Kansas in the United States; in Saskatchewan and Alberta, Canada;
in South Africa; and in Russia
Helium is also present in the Earth’s atmosphere Some of this helium was produced by radioactive de-cay in the Earth and subsequently escaped into the air However, high-energy cosmic rays hitting the Earth’s atmosphere also produce helium by spallation, a pro-cess in which a heavier nucleus breaks into two or more lighter nuclei when it is hit by a high-energy par-ticle Radioactive decay produces only helium 4, while spallation produces both helium 3 and helium 4 Thus, atmospheric helium has a much higher content
of helium 3 than the helium obtained from natural gas wells
History Helium was discovered in 1868 A French astronomer, Pierre Janssen, observed the emission spectrum of the Sun’s chromosphere during the August 18 solar eclipse He saw a yellow-orange emission line that did not correspond to that of any known element Later that year, both Janssen and an English astronomer,
Trang 2Sir Norman Joseph Lockyer, observed this emission
again Lockyer named this new element helium, for
the Sun (helios in Greek).
In 1889, William Hildebrand, an American
min-eral chemist, extracted a gas from a uranium-bearing
mineral, uranite Sir William Ramsay, an English
chemist, performed a similar extraction on cleveite,
another uranium-bearing mineral Ramsey sent the
gas to Lockyer, who showed in 1895 that it had the
same emission lines he previously observed in the
Sun, providing the first identification of helium on
Earth
Obtaining Helium
The U.S Bureau of Mines, which established three
ex-perimental plants to extract helium from the Petrolia
natural gas field in Clay County, Texas, had produced
about 6,000 cubic meters of helium by 1920
Helium-bearing well gas, typically about 80 percent methane,
is compressed and then treated to remove carbon
di-oxide, hydrogen sulfide, and water vapor The
re-maining gas is cooled to a temperature of about−150°
Celsius, which liquefies almost all the hydrocarbons,
leaving nitrogen and helium in the gas phase This gas
is compressed again, then cooled to −196°
Cel-sius, at which point the nitrogen liquefies, leaving
almost pure helium in the gas phase
Uses of Helium
Helium has a much lower density than air; thus a
helium-filled balloon will rise The first practical
application of helium was as a lifting gas for
lighter-than-air craft Although hydrogen has an
even lower density, making it a more efficient
lift-ing gas than helium, the extreme flammability of
hydrogen makes its use dangerous The U.S Navy
experimented with rigid airships, called
dirigi-bles, during the 1920’s and 1930’s In the modern
era, the Goodyear Aircraft Corporation built a
se-ries of nonrigid airships, called blimps, which
have been used as platforms for aerial
photogra-phy Helium-filled balloons are also used for
sci-entific research in the upper atmosphere
In 1908, Heike Kamerlingh Onnes, a physicist
at the University of Leiden, in Holland, liquefied
helium by compressing it to a high pressure,
cool-ing it, then allowcool-ing the helium to expand through
a small opening Expansion causes a gas to cool,
and some of the helium liquefied
Since the boiling point of helium under 1
at-mosphere of pressure is −268.9° Celsius, material brought into contact with liquid helium cools rapidly
In 1911, Kamerlingh Onnes demonstrated that the electrical resistance of mercury vanishes at liquid he-lium temperature He had discovered superconduc-tivity
Helium is used to dilute oxygen in the breathing gas used by deep-sea divers Divers must breath an at-mosphere at the same pressure as the surrounding water At ocean depths the pressure is high, and both oxygen and nitrogen dissolve in body fluids The oxy-gen is consumed, but the nitrooxy-gen remains in the flu-ids If divers return suddenly to the surface, they can suffer the “bends,” which results when the nitrogen expands rapidly The substitution of helium, the least soluble gas known, for nitrogen allows divers to oper-ate at depth and then return to the surface more quickly
George J Flynn
Further Reading
Cook, Gerhard A Argon, Helium, and the Rare Gases: The Elements of the Helium Group 2 vols New York:
Interscience, 1961
Summaries, 2009
Data from the U.S Geological Survey,
U.S Government Printing Office, 2009.
Cryogenic applications 28%
Pressurizing
& purging 26%
Welding cover gas 20%
Controlled atmospheres 13%
Leak detection 4%
Breathing mixtures 2%
Other 7%
U.S End Uses of Helium
Trang 3Greenwood, N N., and A Earnshaw “The Noble
Gases: Helium, Neon, Argon, Krypton, Xenon,
and Radon.” In Chemistry of the Elements 2d ed
Bos-ton: Butterworth-Heinemann, 1997
Henderson, William “The Group 18 (Noble Gas)
Ele-ments: Helium, Neon, Argon, Krypton, Xenon,
and Radon.” In Main Group Chemistry Cambridge,
England: Royal Society of Chemistry, 2000
Krebs, Robert E The History and Use of Our Earth’s
Chemical Elements: A Reference Guide Illustrations by
Rae Déjur 2d ed Westport, Conn.: Greenwood
Press, 2006
Ojima, Minoru, and Frank A Podosek Noble Gas
Geo-chemistry 2d ed New York: Cambridge University
Press, 2002
Simpson, Charles H Chemicals from the Atmosphere.
Garden City, N.Y.: Doubleday, 1969
Web Site
U.S Geological Survey
Helium: Statistics and Information
http://minerals.usgs.gov/minerals/pubs/
commodity/helium
See also: Atmosphere; Gases, inert or noble;
Hydro-gen; Oil and natural gas drilling and wells; Oil and
natural gas reservoirs
Hemp
Category: Plant and animal resources
Where Found
Hemp, Cannabis sativa, is indigenous to temperate
re-gions in Asia All major industrialized countries but
the United States cultivate hemp for its fibers and
oil-rich seeds The former Soviet Union was the world’s
leading producer until the 1980’s Ukraine and Russia
are the two major producers, followed by China,
Can-ada, Austria, Australia, Great Britain, North Korea,
Hungary, Romania, Poland, France, Italy, and Spain
Primary Uses
Cannabis was initially spread around the world
be-cause of its fiber, not its intoxicant chemicals or its
nu-tritious oil seeds It is one of the oldest sources of
tex-tile fiber, whose use for cloth can be traced to 8000
b.c.e in China and the Middle East Hemp fiber is
also used for the manufacture of cordage, sail cloth, and fish nets Oil extracted from seeds is used in paints, medicines, and foods
Technical Definition
Cannabis sativa is a multipurpose plant that has long
been cultivated for its (bast) fiber in the stem, versatile oil in the seeds, and a resin secreted by its leaves that contains a compound, tetrahydrocannabinol (THC), known to have psychotropic effects The somewhat confusing common names hemp and marijuana have
been applied loosely to all three forms of Cannabis sativa However, this essay focuses primarily on its
fi-ber and seed uses The plants are dioecious annual herbs that produce fibers of the best quality when cul-tivated under temperate and warm conditions Hemp produces the longest bast fiber among plants Seeds are rich in oil, which is extracted and used in a variety
of products
Description, Distribution, and Forms
Cannabis is the generic name for hemp, a highly
adap-tive and successful species cultivated throughout tem-perate and tropical regions across the globe The
clas-sification of Cannabis has been a source of much
controversy for a long time It was first thought a rela-tive of the nettle and later considered a member of
the Moraceae family Finally, Cannabis was classified
into its own family, Cannabaceae, in which the genus
Cannabis and Humulus lupulus (hops) are included It was first named in 1753 by Carolus Linnaeus as Canna-bis sativa, which means “useful hemp” in Latin More confusion concerning the taxonomy of Can-nabis resulted from the naming of two other closely related “species,” Cannabis indica, by Jean-Baptiste Lamarck, for hemp plants in India, and Cannabis ruderalis, by a Russian botanist, for wild Cannabis
plants he observed in western Siberia and central
Asia Even today, some still doubt that Cannabis sativa and Cannabis indica are two different species Nevertheless, Cannabis sativa is the most
wide-spread among the three It is a tall, thin annual that grows from 1.5 to 4.5 meters, with most leaves concen-trated at the top The leaves are dark green in color, and each consists of five to nine serrated tapering leaf-lets with sharp ends and measures at 5 to 13 centime-ters long and 0.76 to 2 centimecentime-ters wide The stem is angular, hollow, branched on top, and covered by fine hairs Plants can grow in both loamy soil and poor sandy soil They can grow in altitudes as high as 2,500
Trang 4meters Cannabis requires plenty of light and is less
tol-erant to low temperatures Male plants are generally
taller than female ones Male flowers also bloom two
to four weeks earlier than female flowers and are
small, with colors ranging from pale green, yellow,
and brown to purple-red Female flowers are bundled
tightly together into clusters
The cultivation of Cannabis sativa is easy Seeds
are planted 15 to 20 centimeters apart Plants grow
quickly, up to 15 centimeters a day, with an average
daily growth of 2 to 5 centimeters in height Fruits
(achenes) mature 10 to 35 days after fertilization,
each containing one seed The entire life cycle can be
completed within 70-110 days Cannabis sativa can
grow in almost any soil, requiring little fertilizer, and
is resistant to pests and tolerant to weeds Hemp
culti-vation and processing was one of the world’s most
significant industries until the mid-1800’s The
labor-intensive work of harvesting and extracting fibers
from the stalk, combined with the emergence of more
easily extracted fiber sources such as cotton and jute,
doomed hemp’s status as the top fiber crop
History
Cannabis is generally believed to have originated from
the temperate regions of central Asia, near the Irtysh
River, along the edge of the Gobi Desert, or the
Taklimakan Desert in China’s Xinjiang Uygur
Prov-ince, north of Tibet Hemp cultivation and use date
back to prehistoric times in the Middle East and
China, where the fiber was used for textiles, the seeds
for food, and the oil for various products Hemp fiber
imprints found in pottery shards in Taiwan were more
than 10,000 years old The ancient Asian societies
used hemp fibers to make clothes, shoes, ropes, and a
primitive form of paper Evidence for such uses was
uncovered in the Great Wall of China and dates back
to as early as 10,200 years ago
Hemp was introduced to western Asia and Egypt
and, subsequently, to Europe between 1000 and 2000
b.c.e Extensive hemp cultivation in Europe began
around 500 b.c.e From 1500 to 1700 c.e., hemp
(along with flax) was the major fiber crop in Russia
and Europe In 1545, the Spanish brought hemp to
South America (Chile) The earliest cultivation of
hemp in North America took place in 1606, by French
botanist Louis Hébert in Port Royal, Acadia (now in
Nova Scotia) Hemp was first grown in New England
by Puritans in 1645 By 1850, hemp was the third
larg-est crop in the United States
Obtaining Hemp Hemp is raised and harvested in temperate regions Upon harvest, seeds are separated from the stalks, whose leaves had been stripped off The stalks are then processed to extract fibers through retting, pounding, and scutching Retting begins with sub-merging the flax stems in water and ends with bacteria rotting away cellular tissues and gummy substances, leaving the outer fibers intact Following retting, the stalk is pounded and broken up into short bits, leav-ing the fiber unharmed The scutchleav-ing acts to comb nonfiber residues out of the fiber
Following these steps, the well-processed hemp fi-ber appears creamy white and soft and has a silky sheen Hemp fiber so extracted was used by Levi Strauss to make the original set of jeans However, most hemp fiber is extracted as quickly and inexpen-sively as possible As a result, hemp is mostly used for cordage, rope, canvas, and sailcloth Fibers for human cloth, including jeans, are obtained primarily from cotton
Uses of Hemp
All parts of Cannabis plants are useful For centuries, Cannabis has been the source of a versatile natural
fi-ber and oil-rich seeds Major uses of industrial hemp include, but are not limited to, body care products, construction, essential oils, food, livestock bedding and feed, medicines, molded plastics, nutritional sup-plements, paper products, and textiles
Hemp oil contains omega-3, -6, and -9 fatty acids, which nourish skin and thus can be included in many cosmetic products, such as baby moisturizer, facial cream, shaving cream, shampoo, and conditioner The mineral oil typically used in these products has been derived from fossil fuel, the use of which is not sustainable or environmentally friendly For construc-tion, hemp plants can be used to make caulking, ce-ment, fiberboard, flooring, insulation, paneling, plas-ter, plywood, and roofing Hemp oil can be used to produce nontoxic paint, varnish, and detergent The essential oil is used as emulsion in medicines and is a key ingredient in nutritional supplements More im-portant, hemp seeds contain high levels of proteins and essential fatty acids, which make hemp a premier food source
The plant residues that remain after harvest and processing are an excellent source of animal bedding Meal after oil extraction from seeds contains 30 per-cent proteins, carbohydrates, and mineral nutrients
Trang 5and is often used as feed for livestock Because of its
high biomass in a wide range of habitats, hemp has an
unmatched potential to be a source of biofuel, either
ethanol or biodiesel
Above all, however, is the versatility of hemp fiber
Hemp fiber has been valued for three characteristics:
length, strength, and durability The primary bast
fi-bers in the bark can reach up to 40 millimeters long,
making it a great raw material for papers, clothing,
and textiles The use of hemp fibers in cloth was more
common than that of linen until the fourteenth
cen-tury Hemp paper is bleached with hydrogen
perox-ide, a much more environmentally friendly chemical
than chlorine bleach, which is required by tree-based
paper mills and pollutes water sources heavily By the
1820’s, hemp fibers were used to make 90 percent of the canvas sails, caulk, fish nets, and rigging for ships because of their strength and resistance to decay and salt water Hemp was considered to provide the very best of canvas for painting Estimates indicate that five thousand textile products and as many as twenty-five thousand other products could be produced using hemp Because hemp is adaptable to a wide range of habitats, has an extremely high biomass, and can be used in a variety of products, legalizing its cultivation may be inevitable in the near future
Ming Y Zheng
Further Reading
Bócsa, Iván, and Michael Koras The Cultivation of Hemp: Botany, Varieties, Cultivation, and Harvesting.
Translated by Chris Filben Sebastopol, Calif.: Hemptech, 1998
Brown, L R., et al State of the World, 1998: Worldwatch Institute Report on Progress Toward a Sustainable Soci-ety New York: W W Norton, 1998.
Conrad, C Hemp: Lifeline to the Future—The Unexpected Answer for Our Environmental and Economic Recovery.
Los Angeles: Creative Expressions, 1994
Leizer, C., et al “The Composition of Hemp Seed Oil and Its Potential as an Important Source of
Nutri-tion.” Journal of Nutraceuticals Functional and Medi-cal Foods 2, no 4 (2000): 35-54.
Roulac, John W Hemp Horizon: The Comeback of the World’s Most Promising Plant White River Junction,
Vt.: Chelsea Green, 2006
Small, E., and D Marcus “Hemp: A New Crop with
New Uses for North America.” In Trends in New Crops and New Uses, edited by Jules Janick and Anna
Whipkey Alexandria, Va.: ASHS Press, 2002
Web Sites Hemp Industries Association http://thehia.org/
North American Industrial Hemp Council, Inc Hemp Facts
http://www.naihc.org/hemp_information/
hemp_facts.html
See also: Agricultural products; American Forest and Paper Association; Biodiversity; Biofuels; Cotton; Flax; Hydroponics; Paper; Paper, alternative sources of; Plant fibers; Plants as a medical resource; Renewable and nonrenewable resources; Textiles and fabrics
Numerous products are derived from hemp, including this shoe from
the company Simple, featuring a design by a California teenager.
(Mike Blake/Reuters/Landov)
Trang 6Categories: Environment, conservation, and
resource management; pollution and waste
disposal
Herbicides are a class of pesticide used to kill or
other-wise control unwanted vegetation They are frequently
employed in agriculture and forestry.
Background
Herbicides are used for the control of grasses, weeds,
and other plant pests These chemical compounds
kill plants or inhibit their normal growth In general,
herbicides work by interfering with photosynthesis, so
that a plant dies from lack of energy, or by a
combina-tion of defoliacombina-tion (leaf removal) and systemic
herbi-cidal action
Herbicides are used to clear rights-of-way beneath
power lines and along railways and roads In
agricul-ture and forest management, they are used to control
weeds or to remove the leaves from some crop plants
to facilitate harvesting While herbicides may be
em-ployed in lieu of tillage, their use is more often in
con-junction with tillage and other agronomic practices
During wartime, defoliants and other herbicides have
been used to destroy plants that an enemy uses for
cover during battle or for food
Types of Herbicides
Herbicides may be selective or nonselective Selective
herbicides, such as amitrole, atrazine, monuron,
pyr-idine, 2,4-dichlorophenoxyacetic acid (2,4-D), and
2,4,5-trichlorophenoxyacetic acid (2,4,5-T), target a
particular plant pest and will kill or stunt weeds among
crop plants without injuring the crop For example,
2,4-D targets soft-stemmed plants, while 2,4,5-T is
ef-fective against woody plants Cereals are crops
partic-ularly suited for treatment with 2,4-D, since the
com-pound does not harm narrow-leafed plants but kills
broad-leaved weeds Selective toxicity minimizes the
environmental impact of an herbicide Nonselective
herbicides (also called broad-spectrum or
general-usage herbicides) are toxic to all plants Examples
in-clude dinoseb, diquat, paraquat, and arsenic trioxide
Nonselective compounds are best suited for areas
where all plant growth is to be suppressed, such as
along railroad rights-of-way
Some compounds, known as contact herbicides,
kill only those plant parts to which they are directly applied Others, called systemic herbicides, are ab-sorbed through the plant’s foliage or roots and car-ried to other parts of the plant When mixed with the soil, some herbicides kill germinating seeds and small seedlings
Popular inorganic herbicides include ammonium sulfate, sodium chlorate, sulfuric acid solutions, and borate formulations Among the organic herbicides are the organic arsenicals, substituted amides and ureas, nitrogen heterocyclic acids, and phenol deriva-tives Phenoxyaliphatic acids and their derivatives, a major group of organic herbicides, are selective poi-sons that readily travel from one part of a plant to an-other
History Agricultural societies have used simple chemical her-bicides such as ashes and common salts for centuries
In 1896, a fungicidal compound known as Bordeaux mixture (a combination of copper sulfate, lime, and water) was found also to be effective against some weeds Subsequently, copper sulfate was employed as
a selective weed killer in cereal crops By the early 1900’s, sodium arsenate solutions and other selective inorganic herbicidal mixtures had been developed
In 1932, dinitrophenol compounds were introduced
In the early 1940’s, a new generation of herbicidal compound emerged In an attempt to mimic natural plant hormones, the defoliant 2,4-D was created At low concentrations 2,4-D promotes retention of fruit and leaves; at higher concentrations, it overstimulates plant metabolism, causing the leaves to drop off A re-lated chemical, 2,4,5-T, came into general use in 1948 The years after World War II saw the first large-scale application of herbicides in agriculture and other areas The new defoliants rapidly gained acceptance because of their effectiveness against broad-leaved weeds in corn, sorghum, small grains, and grass pas-tures
A few years after their development, these defoli-ants were employed as chemical weapons During its conflict with Communist guerrillas in Malaya during the late 1940’s and early 1950’s, Britain sprayed
2,4,5-T on crops and jungle foliage to deprive the guerrillas
of food and cover The United States conducted a sim-ilar antifood and antifoliage campaign in South Viet-nam during the 1960’s In this campaign, dubbed
“Operation Ranch Hand,” massive quantities of her-bicidal mixtures were sprayed from aircraft onto
Trang 7Viet-cong food plantations, infiltration routes, staging
ar-eas, and bases The quantity and frequency of the
spraying greatly exceeded recommended levels; in
addition, mechanical problems or military need
of-ten forced aircraft to dump their herbicide loads all at
once, drenching the jungle below Soldiers, civilians,
and the environment were subjected to unusually
high concentrations of defoliants One of the
herbi-cides used in this campaign was Agent Orange, a
mix-ture that included 2,4-D and 2,4,5-T Commercial
preparations of 2,4,5-T contain varying amount of
di-oxin, a highly toxic contaminant Agent Orange has
been implicated in the increased incidence of still
births and birth defects among the Vietnamese living
in the areas sprayed, in the cancers and other illnesses
suffered by American and Australian soldiers who
were involved in the operation, and in birth defects
among the children of these veterans In 1970, the
United States placed severe restrictions on domestic
and agricultural use of 2,4,5-T, at about the same time
the defoliation campaign was halted
U.S Regulation of Herbicides
In 1947, the Federal Insecticide, Fungicide, and
Ro-denticide Act (FIFRA) authorized the United States
Department of Agriculture (USDA) to oversee
regis-tration of herbicides and other pesticides and to deter-mine their safety and effectiveness In December, 1970, the newly formed United States Environmental Protec-tion Agency (EPA) assumed statutory authority from the USDA over pesticide regulations Under the Fed-eral Environmental Pesticide Control Act of 1972, an amendment to FIFRA, manufacturers must register all marketed pesticides with the EPA before the product
is released Before registration, the chemicals must undergo exhaustive trials to assess their potential im-pact on the environment and human health The EPA’s decision to grant registration is based on the de-termination that unreasonable adverse effects on hu-man health or the environment are not anticipated within the constraints of approved usage Beginning
in October, 1977, the EPA classified all pesticides to which it has granted registration as either a restricted-usage (to be applied only by certified pest control op-erators) or unclassified (general-usage) pesticide
Karen N Kähler
Further Reading
Clark, J Marshall, and Hideo Ohkawa, eds Environ-mental Fate and Safety Management of Agrochemicals.
Washington, D.C.: American Chemical Society, 2005
A plane is used to spray herbicide on a rice field in Arkansas (Robert Cohen/The Commercial Appeal/Landov)
Trang 8_ New Discoveries in Agrochemicals Washington,
D.C.: American Chemical Society, 2005
Crone, Hugh D Chemicals and Society: A Guide to the
New Chemical Age New York: Cambridge University
Press, 1986
Monaco, Thomas J., Stephen C Weller, and Floyd M
Ashton Weed Science: Principles and Practices 4th ed.
New York: Wiley, 2002
Vencill, William K., et al., eds Herbicide Handbook 8th
ed Lawrence, Kans.: Weed Science Society of
America, 2002
Ware, George W Complete Guide to Pest Control: With
and Without Chemicals 4th ed Willoughby, Ohio:
MeisterPro Information Resources, 2005
_ Fundamentals of Pesticides: A Self-Instruction
Guide 2d ed Fresno, Calif.: Thomson, 1986.
Zimdahl, Robert L Fundamentals of Weed Science
Bos-ton: Elsevier/Academic Press, 2007
Web Sites
Agriculture and Agri-Food Canada
Manure, Fertilizer, and Pesticide Management in
Canada
http://www4.agr.gc.ca/AAFC-AAC/display-afficher.do?id=1178825328101&lang=eng
Health Canada
Pesticides and Pest Management
http://www.hc-sc.gc.ca/cps-spc/pest/index-eng.php
U.S Environmental Protection Agency
Pesticides
http://www.epa.gov/pesticides/index.htm
See also: Agriculture industry; Environmental
Pro-tection Agency; Food chain; Monoculture
agricul-ture; Pesticides and pest control
Hill, James Jerome
Category: People
Born: September 16, 1838; Rockwood, Upper
Canada (now in Ontario, Canada)
Died: May 29, 1916; St Paul, Minnesota
James Jerome Hill was a railroad entrepreneur who
contributed greatly to American economic growth He
was also a conservationist and proponent of natural
science He wrote books, gave lectures, and financially endorsed advanced scientific farming methods for opti-mum agricultural land management.
Biographical Background James Jerome Hill had nine years of formal schooling, leaving upon the death of his father in 1852 He stud-ied math and land surveying, then learned bookkeep-ing and later worked for wholesalers, dealbookkeep-ing with freight and fuel shipping and supply Within a de-cade, Hill had begun his own freight transportation business, soon owning both steamboat and coal busi-nesses Hill also entered banking and began buying
up bankrupt companies, remaking and selling them for a great profit When the St Paul and Pacific Rail-road went bankrupt during the Panic of 1873, Hill went into financial collaboration with four others and bought the line As general manager, Hill bargained for trackage rights, upgraded the Great Northern, and built rails through the upper Midwest, the Great Plains, and the Pacific Northwest, from Minnesota to Montana
As Hill came upon areas where industry was weak,
he bought and placed companies along the railroad
James Jerome Hill was a railroad executive cum conservationist who was a proponent of agricultural land management (Hulton
Ar-chive/Getty Images)
Trang 9lines He also promoted European immigration,
pay-ing travel and settlement expenses for incompay-ing
im-migrants Knowing the railroad business and the
changes occurring in it, Hill bargained for better
rates Knowing grain and other markets, Hill stayed
keen to the fluctuations in agricultural management
Acknowledging that his rail business shipped mostly
agricultural products, Hill came to be concerned
about water and land use, misuse, and what would
be-come known as sustainable resource management
Impact on Resource Use
A savvy entrepreneur and a staunch conservationist,
Hill took interest in both high-yield agriculture and
sustainable resources With concern for how farming
practices degraded the soil, he began to experiment
with crop rotation, hybridizing Russian wheat in the
Dakotas and developing superior livestock—using the
manure to yield superior crops and to conserve soil
quality He toured the country-fair circuit, speaking to
farmers on the subject of sustainable farming and
conservation, the topic of several books he wrote to
further the cause He created his own lab and hired
agronomists to analyze soil and train farmers, whom
he paid to practice the contemporary techniques He
also purchased livestock for farmers, extracting from
them only the promise to make the prize hogs, rams,
and bulls available for breeding
Hill’s work was so impressive that President
Theo-dore Roosevelt was prompted to hold a White House
conference on conservation in 1908—despite Hill’s
contention that natural resource control should stay
at state and local levels Hill not only was keen on
agri-cultural management but also was a financial expert
Together these traits made the economic concerns
of conservative land management Hill’s number-one
focus
Roxanne McDonald
Web Sites
HistoryLink.org
Spokane Neighborhoods: Hillyard
Http://www.historylink.org/
index.cfm?DisplayPage=output.cfm&File_
Id=7294
Rail Serve
James J Hill
http://www.railserve.com
See also: Agriculture industry; Agronomy; Animal breeding; Conservation; Conservation biology; Soil management
Horticulture
Categories: Scientific disciplines; environment, conservation, and resource management
Horticulture is the branch of agriculture that is con-nected with the production of plants that are directly used by humans for food, medicine, and aesthetic pur-poses.
Background The ability to produce crops, particularly those crops associated with food and fiber, is a major economic and natural resource Horticulture, a multibillion-dollar-per-year industry, is a multidisciplinary science that encompasses all aspects of production, for fun or profit, of intensively cultivated plants to be utilized by humans for food, medicinal purposes, or aesthetic satisfaction Crop production is largely determined by
a variety of environmental conditions, including soil, water, light, temperature, and atmosphere There-fore, horticulture science is primarily concerned with the study of how to manipulate the plants or these en-vironmental factors to achieve maximum yield Since there is tremendous diversity in horticultural plants, the field is subdivided into pomology, the growth and production of fruit crops; olericulture, the growth and production of vegetable crops; landscape horti-culture, the growth and production of trees and shrubs; and floriculture, the growth and production
of flower and foliage plants Each of these subdivi-sions is based on a fundamental knowledge of plant-soil interactions, plant-soil science, plant physiology, and plant morphology
Propagation Horticulture science is concerned with all aspects of crop production, from the collection and germina-tion of seed to the final marketing of the products Plant propagation, protection, and harvesting are three areas of particular interest to horticulturists Generally, propagation from seed is the most com-mon and least expensive way of propagating plants In order to prevent cross-pollination from undesirable
Trang 10varieties, plants to be used for seed production are
grown in genetic isolation from other, similar plants
At maturity, the seed is collected and is usually stored
at low temperatures and under 50 to 65 percent
rela-tive humidity to maintain full viability The seed is
of-ten tested for viability prior to planting to determine
the percentage of seed that should germinate At the
appropriate time, the seed is usually treated with a
fungicide to ensure an adequate crop stand and
planted under proper temperature, water, and light
conditions For most crops, the seed is germinated in
small containers, and the seedlings are then
trans-planted to the field or greenhouse
For many horticultural crops it is not feasible to
produce plants from seed For some, the growth from
seed may require too much time to be economically
practical In other cases, the parent plants may
pro-duce too little or no viable seed, and in still others,
there may be a desire to avoid hybridization in order
to maintain a pure strain For some plants, almost any
part of the root, stem, or leaf can be vegetatively
prop-agated, but chemical treatment of the detached por-tion to ensure regenerapor-tion of the missing tissue is of-ten required
For other plants, a variety of specific vegetative plant tissues, including the roots, bulbs, corms, rhi-zomes, tubers, and runners, must be used for propa-gation Individual runners are used for propagation purposes, but a number of cuttings can be propagated from one rhizome Tubers are propagated by slicing the organ into several pieces, each of which must con-tain an “eye” or bud Corms and bulbs are propagated
by planting the entire structure A relatively new pro-cess of generating plants from cell cultures grown in the laboratory, called tissue culture, is a method often used to propagate pure lines of crops with a high eco-nomic value Grafting, a specialized form of vegetative propagation, is particularly useful in tree farming The shoot from one plant with a particularly desirable fruit quality can be grafted onto the root stock of an-other, more vigorous plant with a less desirable fruit quality
The Chinese floral industry has vigorously expanded since the year 2000 (Xinhua/Landov)