History.

In 1886, Charles Martin Hall, a graduate of Oberlin College, discovered the process of smelting aluminium, almost simultaneously with Paul Héroult in France. He realized that by passing an electric current through a bath of cryolite and aluminium oxide, the then semi-rare metal aluminium remained as a byproduct. This discovery, now called the Hall–Héroult process, is still the only process used to make aluminium (however, see also Bayer process). Probably fewer than ten sites in the United States and Europe produced any aluminium at the time. In 1887, Hall made an agreement to try his process at the Electric Smelting and Aluminum Company plant in Lockport, New York, but it was not used and Hall left after one year. On Thanksgiving Day 1888, with the help of Alfred E. Hunt, he started the Pittsburgh Reduction Company with an experimental smelting plant on Smallman Street in Pittsburgh, Pennsylvania. In 1891, the company went into production in New Kensington, Pennsylvania. In 1895, a third site opened at Niagara Falls. By about 1903, after a settlement with Hall's former employer, and while its patents were in force, the company was the only legal supplier of aluminium in the United States.  By 1902 New Kensington consisted of 173,000 sq. feet on 15 acres with 276 employees and the company operated hydropower and reduction plants in Niagara Falls, NY (1895), Shawinigan Falls, Quebec (1900), mining operations in Bauxite, AR (1901) and reduction facilities in East St. Louis, IL (1902). "The Aluminum Company of America" became the firm's new name on January 1, 1907. The acronym "Alcoa" was coined in 1910, given as a name to two of the locales where major corporate facilities were located (although one of these has since been changed), and in 1999 was adopted as the official corporate name.  From 1902 until 1915 additional plants in Massena, NY (1903), Alcoa, TN (1911), Edgewater, NJ (1915), Badin, NC (1915) came online while New Kensington had 31 buildings in the complex housing six departments (tubes, sheets, rods, bar and wire, extrusion, jobbing, foil) and two subsidiaries (Aluminum Cooking Utensil Company and Aluminum Seal Company). In 1907 it created the "company town" of Pine Grove, New York, for workers outside Massena. In Baden, Alcoa, Maryville and elsewhere the company funded the construction of schools, parks, playgrounds and medical facilities.  By the end of World War I Alcoa's New Kensington facility accounted for 3,292 workers—a fifth of the local population—and covered over 1 million square feet of manufacturing space on 75 acres.  In 1938, the Justice Department charged Alcoa with illegal monopolization, and demanded that the company be dissolved. The case of "United States v. Alcoa" was settled six years later.  In 1963, John D. Harper, a Tennessee native who had started with the company in 1925, then was hired, in 1933, as an electrical engineer, following his graduation from the University of Tennessee, and who had subsequently served as vice president and director; was named president of Alcoa, then CEO, in 1965, then chairman, in 1970, serving until his retirement from Alcoa, in 1975. Harper was also a director of Mellon Bank N.A., Goodyear Tire and Rubber Company and Procter & Gamble, and a trustee of Carnegie-Mellon University. An advocate of close associations between business and government;  In 1998, Alcoa acquire Alumax in a cash and share deal for $2.8 billion. Alcoa paid $50 a share in cash for half of the shares and 0.6975 Alcoa share for each of the remaining Alumax shares. Alcoa also assumed $1 billion in debt. Alumax's assets included the Eastalco aluminum smelter in Adamstown Maryland, the Intalco aluminum smelter in Ferndale Washington, and the Kawneer brand of building construction products.  In 2000, Alcoa acquired Reynolds Metals Co. in an all-share deal for $4.5 billion. To clear anti-competition regulatory hurdles, Alcoa was required to sell Reynolds's 25% interest in a Washington smelter and all of Reynolds's alumina refineries. Reynolds owned a 56% interest in the Worsley alumina refinery in Australia, 50% interest in a refinery in Germany and 100% interest in a Texas refinery. Alcoa also planned to sell Reynolds's construction and distribution business and the company's $400 million transportation business. Alcoa sold its packaging and consumer business, formerly called Reynolds Metals, to the Rank Group for $2.7 billion in 2008.  In 2000, Alcoa also purchased Cordant Technologies Inc. for $57 a share in cash, or $2.3 billion, and also assumed $685 million of Cordant's debt for a total transaction value of $2.9 billion. Cordant's divisions included Huck Fasteners, Jacobson Mfg. Co., Continental/Midland Group, its 85% interest in Howmet International Inc., and Thiokol Corporation. In 2001, Alcoa sold Thiokol for $2.9 billion to Alliant Techsystems (ATK).  Alcoa purchased an 8% stake of Aluminium Corporation of China (Chalco) in 2001. It tried to form a strategic alliance with China's largest aluminium producer, at its Pingguo facility; however, it was unsuccessful. Alcoa sold their stake in Chalco on September 12, 2007, for around $2 billion.  In 2004, Alcoa's specialty chemicals business was sold to two private equity firms led by Rhône Group for an enterprise value of $342 million, which included the assumption of debt and other unfunded obligations. Rhône Group then changed the name to Almatis, Inc.  In 2005 Alcoa acquired two major production facilities in Russia, at Samara and Belaya Kalitva.  In 2005, Alcoa began construction in Iceland on Alcoa Fjarðaál, a state-of-the-art aluminium smelter and the company's first greenfield smelter in more than 20 years, albeit under heavy criticism by local and international NGOs related to a controversial dam project exclusively dedicated to supplying electricity to this smelter. Also, Alcoa has completed or is undergoing primary aluminium expansion projects in Brazil, Jamaica, and Pinjarra, Western Australia.  In 2006, Alcoa relocated its top executives from Pittsburgh to New York City. Although the company's principal office was relocated to New York City, the company's operational headquarters were still located at its Corporate Center in Pittsburgh. Alcoa employed approximately 2,000 people at its Corporate Center in Pittsburgh and 60 at its principal office in New York.  Alcoa was named one of the top three most sustainable corporations in the world at the World Economic Forum in Davos, Switzerland.  On May 8, 2008, Klaus Kleinfeld was appointed CEO of Alcoa, succeeding Alain Belda. On April 23, 2010, Alcoa's board of directors selected Kleinfeld to the office of chairman, following Belda's planned retirement.  On July 16, 2012, Alcoa announced that it would take over full ownership and operation of Evermore Recycling and make it part of Alcoa's Global Packaging group. Evermore Recycling is a leader in used beverage can recycling, purchasing more recycled cans than any other group worldwide.  In June 2013, Alcoa announced it would permanently close its Fusina primary aluminium smelter in Venice, Italy, where production had been curtailed since June 2010.  On January 9, 2014, Alcoa reached a settlement with the U.S. Securities and Exchange Commission and the U.S. Department of Justice over charges of bribing Bahraini officials. Under the terms of the settlement they will pay the SEC $175 million to settle the charges. To settle the criminal claims with the DoJ, Alcoa World Alumina (AWA, a company within Alcoa World Alumina and Chemicals) is pleading guilty to one count of violating the anti-bribery provisions of the Foreign Corrupt Practices Act (FCPA). AWA will pay the DoJ $223 million in five equal installments over the next four years, bringing the company's total bill for the scandal to $384 million.  In June 2016, Alcoa Inc. announced plans to split itself into two companies. Alcoa Inc would be renamed as Arconic and would take over the business of designing and building processed metal parts, primarily for the automotive and aerospace industries. A new company, Alcoa Corporation, would be set up and spun out of Alcoa Inc. and retain the Alcoa name. Alcoa Corp. would continue the business of mining, smelting, and refining of raw aluminium. The split was completed on November 1, 2016.  In April 2017, Alcoa announced that it would relocate its corporate headquarters back to Pittsburgh as part of a general consolidation of administrative facilities around the world.

Environmental record.

The Political Economy Research Institute ranks Alcoa 15th among corporations emitting airborne pollutants in the United States. The ranking is based on the quantity (13 million pounds in 2005) and toxicity of the emissions. In April 2003, Alcoa Inc. agreed to spend an estimated $330 million to install a new coal-fired power plant with state-of-the-art pollution controls to eliminate the vast majority of sulfur dioxide and nitrogen dioxide emissions from the power plant at Alcoa's aluminium production facility in Rockdale, Texas. The settlement was the ninth case the Bush administration pursued to bring the coal-fired power plant industry into full compliance with the Clean Air Act. Alcoa was unlawfully operating at the Rockdale facility since it overhauled the Rockdale power plant without installing necessary pollution controls and without first obtaining proper permits required by "New Source Review" program of the Clean Air Act. In February 1999, Alcoa cleaned soils and sediment contaminated with polychlorinated biphenyls (PCB) and lead at the York Oil federal Superfund site in Moira, New York, in accordance with the Environmental Protection Agency. The site, a former waste oil recycling storage facility, accepted waste oil from a number of companies, including Alcoa. The facility was improperly managed and operated and, as a result, soils on the York Oil Property and nearby wetlands sediments and groundwater were contaminated. The United States Environmental Protection Agency (EPA) issued a Superfund Unilateral Order on December 31, 1998, requiring Alcoa to excavate, treat and dispose of the contaminated wetlands sediments.

Operations by country.

Jamaica.

Alcoa formed the Alcoa Minerals of Jamaica subsidiary on the island in 1959, shipping their first load of bauxite in 1963 from Rocky Point. Later in 1972, Alcoa established a 500,000 metric tonne per year refinery where they process bauxite into alumina. They have continued to upgrade the plant through the years and its now capable 1,425,000 metric tonnes per year. In 1988 the Jamaican government gained a 50% share in the subsidiary and renamed the operation to Jamalco, Alcoa being the managing partner. Expansion of the operation in 2007 resulted in Alcoa owning a total of 55% of the operation. Alcoa continues to mine bauxite in the Jamaican parishes of Clarendon and Manchester while competitors' operations take place in nearby parishes.

Ghana.

Alcoa's affiliate in Ghana, the Volta Aluminium Company, was completely closed between May 2003 and early 2006, due to problems with its electricity supply.

Guinea.

Alcoa is a major owner of the through Halco Mining, together with Rio Tinto Alcan and the Guinean government. Guinea is the second global producer of bauxite and it is said to have half of the world's reserves.

Iceland.

The Fjardaál smelter in eastern Iceland was completed in June 2007, and brought into full operation the following April. The plant processes 940 tons of aluminium a day, with a capacity of 346,000 metric tons a year, making it Alcoa's second largest capacity smelter. For power, the plant relies on the Kárahnjúkar Hydropower Plant, constructed and operated by the state owned Landsvirkjun specifically for the smelting operation. That project was subject to controversy due to its impact on the environment.  In 2006, Alcoa and the government of Iceland signed an agreement on instigating a thorough feasibility study for a new 250,000 tpy (Tons Per Year) smelter in Bakki by Húsavík in Northern Iceland. In October 2011, the proposed project was dropped because "the power availability and proposed pricing would not support an aluminum smelter".  Alcoa announced plans to close the office in Reykjavik.

Wales.

On November 21, 2006, Alcoa announced that it planned to close the Waunarlwydd works in Swansea, with the loss of 298 jobs. Production ceased at the Swansea plant on January 27, 2007. A small site closure team worked at the site until December 31, 2008. The site is still owned by Alcoa, but is now managed locally and renamed, Westfield Industrial Park. Several of the large buildings are leased out to local businesses.

Australia.

Alcoa operates bauxite mines, alumina refineries and aluminium smelters through Alcoa World Alumina and Chemicals, a joint venture between Alumina Limited and Alcoa. Alcoa operates two bauxite mines in Western Australia—the Huntly and Willowdale mines. Alcoa World Alumina and Chemicals owns and operates three alumina refineries in Western Australia: Kwinana, Pinjarra, and Wagerup. The Wagerup expansion plans have been put on hold due to the Global Financial Crisis. Two aluminium smelters are also operated in the state of Victoria at Portland and Point Henry; the Point Henry smelter was scheduled to be closed in August 2014. Alcoa Australia Rolled Products, a 100% Alcoa Inc. venture, operates two rolling mills. The Point Henry Rolling mill in Victoria and the Yennora rolling mill in N.S.W. have a combined rolling capacity of approx. 200,000 tonnes. Alcoa uses 12,600 GWh or 15% of Victoria's electricity annually.  Alcoa's Western Australian Wagerup plant has a troubled history in the context of claims that pollution from the plant has had an adverse impact on the health of members of the adjacent local community.

United States.

On January 3, 2003, Alcoa opened its new operations headquarters on the North Shore of Pittsburgh. This move came about after it donated its 50-year-old skyscraper headquarters in Downtown Pittsburgh to the Regional Development Authority.  Alcoa created a plant just outside Maryville in Blount County, Tennessee. To support the factory, Alcoa built a small city and named it as such. The Alcoa Tenn Federal Credit Union was the first employee created credit union in the state. The plant is no longer an Alcoa business.  Alcoa's Massena West plant is the longest operating smelter in the United States, having been in continuous operation since 1902. The Reynolds Aluminum Plant became Massena East when the companies merged in 2000.  Alcoa had a smelting plant in Badin, North Carolina from 1917 to 2007 and continued a hydroelectric power operation there until February 1, 2017 when the Yadkin Hydroelectric Project was sold to Cube Hydro.  Alcoa also operates an aluminium smelting plant of similar size to the one in Tennessee in Warrick County, Indiana, just east of Newburgh, Vectren Energy operates a coal power plant on the site to provide electricity.  Alcoa maintains several Research and Development Centers in the United States. The largest one, Alcoa Technical Center, is located East of its Pittsburgh Headquarters at Alcoa Center, Pennsylvania. The "Tech Center" is as large as some college campuses, has its own zip code and maintains an extensive intellectual and physical resource for innovation. Alcoa's extensive safety program continuously improves safety at the Tech Center. After Paul O'Neill became Alcoa CEO in 1987, Alcoa became one of the safest companies in the world, despite the aluminium industry's inherent risks.  Alcoa plans to close offices in Richmond, Virginia; Nashville, Tennessee; and Chicago.

Alcoa Steamship Company.

The "Alcoa Steamship company" was a subsidiary of ALCOA since the company was formed in 1917.

In popular culture.

Alcoa is portrayed as the main sponsor of the CBS' 1953 program "See It Now" in George Clooney's Academy Award–nominated film "Good Night, and Good Luck".

Alcoa Corporation (a portmanteau of "Aluminum Company of America") is an American industrial corporation. It is the world's eighth largest producer of aluminum, with corporate headquarters in Pittsburgh, Pennsylvania. Alcoa conducts operations in 10 countries. Alcoa is a major producer of primary aluminum, fabricated aluminum, and alumina combined, through its active and growing participation in all major aspects of the industry: technology, mining, refining, smelting, fabricating, and recycling.

Alcoa, abréviation de « Aluminum Company of America », () est une entreprise américaine, troisième plus grand producteur d'aluminium au monde derrière Rusal et Rio Tinto Alcan. Son siège opérationnel est situé à Pittsburgh aux États-Unis. En 2006, l'entreprise était présente dans quarante-trois pays et employait personnes. Fin 2015, elle est présente dans trente pays et emploie personnes.


History.

Agriculturalists have long recognized that suitable rotations—such as planting spring crops for livestock in place of grains for human consumption—make it possible to restore or to maintain a productive soil. Ancient Middle Eastern farmers practiced crop rotation in 6000 BC without understanding the chemistry, alternately planting legumes and cereals. In the Bible, chapter 25 of the Book of Leviticus instructs the Israelites to observe a "Sabbath of the Land". Every seventh year they would not till, prune or even control insects.

Two-field system.

Under a two-field rotation, half the land was planted in a year, while the other half lay fallow. Then, in the next year, the two fields were reversed. From the times of Charlemagne (died 814), farmers in Europe transitioned from a two-field crop rotation to a three-field crop rotation.

Three-field system.

From the end of the Middle Ages until the 20th century, Europe's farmers practiced three-field rotation, dividing available lands into three parts. One section was planted in the autumn with rye or winter wheat, followed by spring oats or barley; the second section grew crops such as peas, lentils, or beans; and the third field was left fallow. The three fields were rotated in this manner so that every three years, a field would rest and be fallow. Under the two-field system, if one has a total of of fertile land, one would only plant 300 acres. Under the new three-field rotation system, one would plant (and therefore harvest) 400 acres. But the additional crops had a more significant effect than mere quantitative productivity. Since the spring crops were mostly legumes, they increased the overall nutrition of the people of Northern Europe.

Four-field rotation.

Farmers in the region of Waasland (in present-day northern Belgium) pioneered a four-field rotation in the early 16th century, and the British agriculturist Charles Townshend (1674–1738) popularised this system in the 18th century. The sequence of four crops (wheat, turnips, barley and clover), included a fodder crop and a grazing crop, allowing livestock to be bred year-round. The four-field crop rotation became a key development in the British Agricultural Revolution. The rotation between arable and ley is sometimes called ley farming.

Modern developments.

George Washington Carver (1860s–1943) studied crop-rotation methods in the United States, teaching southern farmers to rotate soil-depleting crops like cotton with soil-enriching crops like peanuts and peas.  In the Green Revolution of the mid-20th century the traditional practice of crop rotation gave way in some parts of the world to the practice of supplementing the chemical inputs to the soil through topdressing with fertilizers, adding (for example) ammonium nitrate or urea and restoring soil pH with lime. Such practices aimed to increase yields, to prepare soil for specialist crops, and to reduce waste and inefficiency by simplifying planting, harvesting, and irrigation.

Crop choice.

A preliminary assessment of crop interrelationships can be found in how each crop: (1) contributes to soil organic matter (SOM) content, (2) provides for pest management, (3) manages deficient or excess nutrients,(4) how it contributes to or controls for soil erosion, (5) interbreeds with other crops to produce hybrid offspring, and (6) impacts surrounding food webs and field ecosystems.  Crop choice is often related to the goal the farmer is looking to achieve with the rotation, which could be weed management, increasing available nitrogen in the soil, controlling for erosion, or increasing soil structure and biomass, to name a few. When discussing crop rotations, crops are classified in different ways depending on what quality is being assessed: by family, by nutrient needs/benefits, and/or by profitability (i.e. cash crop versus cover crop). For example, giving adequate attention to plant family is essential to mitigating pests and pathogens. However, many farmers have success managing rotations by planning sequencing and cover crops around desirable cash crops. The following is a simplified classification based on crop quality and purpose.

Row crops.

Many crops which are critical for the market, like vegetables, are row crops (that is, grown in tight rows). While often the most profitable for farmers, these crops are more taxing on the soil. Row crops typically have low biomass and shallow roots: this means the plant contributes low residue to the surrounding soil and has limited effects on structure. With much of the soil around the plant exposed to disruption by rainfall and traffic, fields with row crops experience faster break down of organic matter by microbes, leaving fewer nutrients for future plants.  In short, while these crops may be profitable for the farm, they are nutrient depleting. Crop rotation practices exist to strike a balance between short-term profitability and long-term productivity.

Legumes.

A great advantage of crop rotation comes from the interrelationship of nitrogen-fixing crops with nitrogen-demanding crops. Legumes, like alfalfa and clover, collect available nitrogen from the atmosphere and store it in nodules on their root structure. When the plant is harvested, the biomass of uncollected roots breaks down, making the stored nitrogen available to future crops..  In addition, legumes have heavy tap roots that burrow deep into the ground, lifting soil for better tilth and absorption of water.

Grasses and cereals.

Cereal and grasses are frequent cover crops because of the many advantages they supply to soil quality and structure. The dense and far-reaching root systems give ample structure to surrounding soil and provide significant biomass for soil organic matter.  Grasses and cereals are key in weed management as they compete with undesired plants for soil space and nutrients.

Green manure.

Green manure is a crop that is mixed into the soil. Both nitrogen-fixing legumes and nutrient scavengers, like grasses, can be used as green manure. Green manure of legumes is an excellent source of nitrogen, especially for organic systems, however, legume biomass does not contribute to lasting soil organic matter like grasses do.

Planning a rotation.

There are numerous factors that must be taken into consideration when planning a crop rotation. Planning an effective rotation requires weighing fixed and fluctuating production circumstances: market, farm size, labor supply, climate, soil type, growing practices, etc. Moreover, a crop rotation must consider in what condition one crop will leave the soil for the succeeding crop and how one crop can be seeded with another crop. For example, a nitrogen-fixing crop, like a legume, should always precede a nitrogen depleting one; similarly, a low residue crop (i.e. a crop with low biomass) should be offset with a high biomass cover crop, like a mixture of grasses and legumes.  There is no limit to the number of crops that can be used in a rotation, or the amount of time a rotation takes to complete. Decisions about rotations are made years prior, seasons prior, or even at the very last minute when an opportunity to increase profits or soil quality presents itself.

Implementation.

Crop rotation systems may be enriched by the influences of other practices such as the addition of livestock and manure, intercropping or multiple cropping, and is common in organic cropping systems.

Incorporation of livestock.

Introducing livestock makes the most efficient use of critical sod and cover crops; livestock (through manure) are able to distribute the nutrients in these crops throughout the soil rather than removing nutrients from the farm through the sale of hay.  Mixed farming or the practice of crop cultivation with the incorporation of livestock can help manage crops in a rotation and cycle nutrients. Crop residues provide animal feed, while the animals provide manure for replenishing crop nutrients and draft power. These processes promote internal nutrient cycling and minimize the need for synthetic fertilizers and large-scale machinery. As an additional benefit, the cattle, sheep and/or goat provide milk and can act as a cash crop in the times of economic hardship.

Intercropping.

Multiple cropping systems, such as intercropping or companion planting, offer more diversity and complexity within the same season or rotation. An example of companion planting is the three sisters, the inter-planting of corn with pole beans and vining squash or pumpkins. In this system, the beans provide nitrogen; the corn provides support for the beans and a "screen" against squash vine borer; the vining squash provides a weed suppressive canopy and a discouragement for corn-hungry raccoons.  Double-cropping is common where two crops, typically of different species, are grown sequentially in the same growing season, or where one crop (e.g. vegetable) is grown continuously with a cover crop (e.g. wheat). This is advantageous for small farms, who often cannot afford to leave cover crops to replenish the soil for extended periods of time, as larger farms can. When multiple cropping is implemented on small farms, these systems can maximize benefits of crop rotation on available land resources.

Organic farming.

Crop rotation is a required practice, in the United States, for farm seeking organic certification. The “Crop Rotation Practice Standard” for the National Organic Program under the U.S. Code of Federal Regulations, section §205.205, states  Farmers are required to implement a crop rotation that maintains or builds soil organic matter, works to control pests, manages and conserves nutrients, and protects against erosion. Producers of perennial crops that aren’t rotated may utilize other practices, such as cover crops, to maintain soil health.  In addition to lowering the need for inputs (by controlling for pests and weeds and increasing available nutrients), crop rotation helps organic growers increase the amount of biodiversity their farms. Biodiversity is also a requirement of organic certification, however, there are no rules in place to regulate or reinforce this standard. Increasing the biodiversity of crops has beneficial effects on the surrounding ecosystem and can host a greater diversity of fauna, insects, and beneficial microorganism in the soil. Some studies point to increased nutrient availability from crop rotation under organic systems compared to conventional practices as organic practices are less likely to inhibit of beneficial microbes in soil organic matter.  While multiple cropping and intercropping benefit from many of the same principals as crop rotation, they do not satisfy the requirement under the NOP.

Benefits.

Agronomists describe the benefits to yield in rotated crops as "The Rotation Effect". There are many benefits of rotation systems. The factors related to the increase are broadly due to alleviation of the negative factors of monoculture cropping systems. Specifically, improved nutrition; pest, pathogen, and weed stress reduction; and improved soil structure have been found in some cases to be correlated to beneficial rotation effects.  Other benefits of rotation cropping systems include production cost advantages. Overall financial risks are more widely distributed over more diverse production of crops and/or livestock. Less reliance is placed on purchased inputs and over time crops can maintain production goals with fewer inputs. This in tandem with greater short and long term yields makes rotation a powerful tool for improving agricultural systems.

Soil organic matter.

The use of different species in rotation allows for increased soil organic matter (SOM), greater soil structure, and improvement of the chemical and biological soil environment for crops. With more SOM, water infiltration and retention improves, providing increased drought tolerance and decreased erosion.  Soil organic matter is a mix of decaying material from biomass with active microorganisms. Crop rotation, by nature, increases exposure to biomass from sod, green manure, and a various other plant debris. The reduced need for intensive tillage under crop rotation allows biomass aggregation to lead to greater nutrient retention and utilization, decreasing the need for added nutrients. With tillage, disruption and oxidation of soil creates a less conducive environment for diversity and proliferation of microorganisms in the soil. These microorganisms are what make nutrients available to plants. So, where "active" soil organic matter is a key to productive soil, soil with low microbial activity provides significantly fewer nutrients to plants; this is true even though the quantity of biomass left in the soil may be the same.  Soil microorganisms also decrease pathogen and pest activity through competition. In addition, plants produce root exudates and other chemicals which manipulate their soil environment as well as their weed environment. Thus rotation allows increased yields from nutrient availability but also alleviation of allelopathy and competitive weed environments.

Carbon sequestration.

Studies have shown that crop rotations greatly increase soil organic carbon (SOC) content, the main constituent of soil organic matter. Carbon, along with hydrogen and oxygen, is a macronutrient for plants. Highly diverse rotations spanning long periods of time have shown to be even more effective in increasing SOC, while soil disturbances (e.g. from tillage) are responsible for exponential decline in SOC levels. In Brazil, conversion to no-till methods combined with intensive crop rotations has been shown an SOC sequestration rate of 0.41 tonnes per hectare per year.  In addition to enhancing crop productivity, sequestration of atmospheric carbon has great implications in reducing rates of climate change by removing carbon dioxide from the air.

Nitrogen fixing.

Rotating crops adds nutrients to the soil. Legumes, plants of the family Fabaceae, for instance, have nodules on their roots which contain nitrogen-fixing bacteria called rhizobia. During a process called nodulation, the rhizobia bacteria use nutrients and water provided by the plant to convert atmospheric nitrogen into ammonia, which is then converted into an organic compound that the plant can use as its nitrogen source. It therefore makes good sense agriculturally to alternate them with cereals (family Poaceae) and other plants that require nitrates. How much nitrogen made available to the plants depends on factors such as the kind of legume, the effectiveness of rhizobia bacteria, soil conditions, and the availability of elements necessary for plant food.

Pathogen and pest control.

Crop rotation is also used to control pests and diseases that can become established in the soil over time. The changing of crops in a sequence decreases the population level of pests by (1) interrupting pest life cycles and (2) interrupting pest habitat. Plants within the same taxonomic family tend to have similar pests and pathogens. By regularly changing crops and keeping the soil occupied by cover crops instead of lying fallow, pest cycles can be broken or limited, especially cycles that benefit from overwintering in residue. For example, root-knot nematode is a serious problem for some plants in warm climates and sandy soils, where it slowly builds up to high levels in the soil, and can severely damage plant productivity by cutting off circulation from the plant roots. Growing a crop that is not a host for root-knot nematode for one season greatly reduces the level of the nematode in the soil, thus making it possible to grow a susceptible crop the following season without needing soil fumigation.  This principle is of particular use in organic farming, where pest control must be achieved without synthetic pesticides.

Weed management.

Integrating certain crops, especially cover crops, into crop rotations is of particular value to weed management. These crops crowd out weed through competition. In addition, the sod and compost from cover crops and green manure slows the growth of what weeds are still able to make it through the soil, giving the crops further competitive advantage. By slowing the growth and proliferation of weeds while cover crops are cultivated, farmers greatly reduce the presence of weeds for future crops, including shallow rooted and row crops, which are less resistant to weeds. Cover crops are, therefore, considered conservation crops because they protect otherwise fallow land from becoming overrun with weeds.  This system has advantages over other common practices for weeds management, such as tillage. Tillage is meant to inhibit growth of weeds by overturning the soil; however, this has a countering effect of exposing weed seeds that may have gotten buried and burying valuable crop seeds. Under crop rotation, the number of viable seeds in the soil is reduced through the reduction of the weed population.  In addition to their negative impact on crop quality and yield, weeds can slow down the harvesting process. Weeds make farmers less efficient when harvesting, because weeds like bindweeds, and knotgrass, can become tangled in the equipment, resulting in a stop-and-go type of harvest.

Preventing soil erosion.

Crop rotation can significantly reduce the amount of soil lost from erosion by water. In areas that are highly susceptible to erosion, farm management practices such as zero and reduced tillage can be supplemented with specific crop rotation methods to reduce raindrop impact, sediment detachment, sediment transport, surface runoff, and soil loss.  Protection against soil loss is maximized with rotation methods that leave the greatest mass of crop stubble (plant residue left after harvest) on top of the soil. Stubble cover in contact with the soil minimizes erosion from water by reducing overland flow velocity, stream power, and thus the ability of the water to detach and transport sediment. Soil Erosion and Cill prevent the disruption and detachment of soil aggregates that cause macropores to block, infiltration to decline, and runoff to increase. This significantly improves the resilience of soils when subjected to periods of erosion and stress.  When a forage crop breaks down, binding products are formed that act like an adhesive on the soil, which makes particles stick together, and form aggregates. The formation of soil aggregates is important for erosion control, as they are better able to resist raindrop impact, and water erosion. Soil aggregates also reduce wind erosion, because they are larger particles, and are more resistant to abrasion through tillage practices.  The effect of crop rotation on erosion control varies by climate. In regions under relatively consistent climate conditions, where annual rainfall and temperature levels are assumed, rigid crop rotations can produce sufficient plant growth and soil cover. In regions where climate conditions are less predictable, and unexpected periods of rain and drought may occur, a more flexible approach for soil cover by crop rotation is necessary. An opportunity cropping system promotes adequate soil cover under these erratic climate conditions. In an opportunity cropping system, crops are grown when soil water is adequate and there is a reliable sowing window. This form of cropping system is likely to produce better soil cover than a rigid crop rotation because crops are only sown under optimal conditions, whereas rigid systems are not necessarily sown in the best conditions available.  Crop rotations also affect the timing and length of when a field is subject to fallow. This is very important because depending on a particular region's climate, a field could be the most vulnerable to erosion when it is under fallow. Efficient fallow management is an essential part of reducing erosion in a crop rotation system. Zero tillage is a fundamental management practice that promotes crop stubble retention under longer unplanned fallows when crops cannot be planted. Such management practices that succeed in retaining suitable soil cover in areas under fallow will ultimately reduce soil loss. In a recent study that lasted a decade, it was found that a common winter cover crop after potato harvest such as fall rye can reduce soil run-off by as much as 43%, and this is typically the most nutritional soil.

Biodiversity.

Increasing the biodiversity of crops has beneficial effects on the surrounding ecosystem and can host a greater diversity of fauna, insects, and beneficial microorganisms in the soil. Some studies point to increased nutrient availability from crop rotation under organic systems compared to conventional practices as organic practices are less likely to inhibit of beneficial microbes in soil organic matter, such as arbuscular mycorrhizae, which increase nutrient uptake in plants. Increasing biodiversity also increases the resilience of agro-ecological systems.

Farm productivity.

Crop rotation contributes to increased yields through improved soil nutrition. By requiring planting and harvesting of different crops at different times, more land can be farmed with the same amount of machinery and labour.

Risk management.

Different crops in the rotation can reduce the risks of adverse weather for the individual farmer.

Challenges.

While crop rotation requires a great deal of planning, crop choice must respond to a number of fixed conditions (soil type, topography, climate, and irrigation) in addition to conditions that may change dramatically from year to the next (weather, market, labor supply). In this way, it is unwise to plan crops years in advance. Improper implementation of a crop rotation plan may lead to imbalances in the soil nutrient composition or a buildup of pathogens affecting a critical crop. The consequences of faulty rotation may take years to become apparent even to experienced soil scientists and can take just as long to correct.  Many challenges exist within the practices associated with crop rotation. For example, green manure from legumes can lead to an invasion of snails or slugs and the decay from green manure can occasionally suppress the growth of other crops.

Crop rotation is the practice of growing a series of different types of crops in the same area across a sequenced of growing seasons. It reduces reliance on one set of nutrients, pest and weed pressure, and the probability of developing resistant pest and weeds.

La rotation culturale (ou rotation des cultures) est, en agriculture, la suite de cultures échelonnées au fil des années sur une même parcelle. C'est un élément important de la gestion de la fertilité des sols et des bioagresseurs, et donc un atout pour l'augmentation des rendements.


Early life and career.

Lázaro Cárdenas del Río was born on May 21, 1895, one of eight children in a lower-middle-class family in the village of Jiquilpan, Michoacán, where his father owned a billiard hall. After the death of his father, from age 16 Cárdenas supported his family (including his mother and seven younger siblings). By the age of 18, he had worked as a tax collector, a printer's devil, and a jail keeper. Although he left school at the age of eleven, he used every opportunity to educate himself and read widely throughout his life, especially works of history.

Military career.

Cárdenas set his sights on becoming a teacher, but was drawn into the military during the Mexican Revolution after Victoriano Huerta overthrew President Francisco Madero in February 1913. Michoacán was far from the revolutionary action that had brought Madero to the Mexican presidency, but after Huerta's coup and Madero's assassination, Cárdenas joined a group of Zapatistas, but Huerta's forces scattered the group, where Cárdenas had served as captain and paymaster. Since revolutionary forces were voluntary organizations, his position of leadership points to his skills and his being paymaster to the perception that he would be honest in financial

Service under President Calles.

Cárdenas was a political protégé of Calles, but his ideological mentor was revolutionary General Francisco J. Múgica, a strongly anticlerical, secular socialist. President Calles appointed Cárdenas Chief of Military Operations in the Huasteca, an oil producing region on the Gulf Coast. Cárdenas

Governor of Michoacan, 1928–1932.

Cárdenas was appointed governor of his home state of Michoacan in 1928, which was then wracked by the political conflict between state and Church, the known as the Cristiada. His ideological mentor Múgica had previously served as the state's governor, and had attempted to counter the power of the Roman Catholic Church through laws. He mobilized groups to support his positions, creating “political shock troops,” consisting of public school teachers and members of a disbanded agrarian league, forming the "Confederación Revolucionaria Michoacana del Trabajo", under the slogan of “Union, Land, Work.” The organization was funded by the state government, although not listed as an official expenditure. It became the single-most powerful organization representing both workers and peasants. Mobilizing worker and peasant support and controlling the organization to which they belonged became the model for Cárdenas when he became president.

Land reform.

As governor, Cárdenas also prioritized distribution of land at a time when President Calles was disillusioned by the program. He expropriated haciendas and created ejidos, collectively held, state-controlled landholdings. Ejiditarios, members of the ejido, worked individual plots of land but did not hold title to it as private property. Opposition to the program came from estate owners (hacendados), the clergy, and in some cases tenant farmers,

Promotion of tourism, art, and indigenous culture.

During his term as governor, Cárdenas sought to bring peace to the state, unite its population divided by the on-going Cristero War, and make Michoacan, especially the historic town of Pátzcuaro into a tourist destination. Once he was president of Mexico, he continued to devote government funding to the project. Cárdenas built a house in Pátzcuaro when he became governor of the state, naming it "La Quinta Eréndira," after the Purépecha princess, who has been identified as Mexico's first anticolonial heroine for her resistance to the Spanish conquest, and a contrasting figure to Malinche, Cortés's cultural translator. Eréndira became a popular historical figure under Cárdenas. At his estate, he commissioned murals for the house, which are now lost, but it is known from historical sources that they had indigenous themes, particularly the rise and fall of the Purépecha Empire at the time of the Spanish conquest. The murals and the texts "appropriate national historical narratives in order to supplant the national myths and locate Mexico's ideal foundations in Michoacan."

Presidential election of 1934.

Calles tapped Cárdenas to be the party's president. Of the revolutionary generals, Cárdenas was considered "honest, able, anticlerical, and politically astute," He had come from a poor and marginal state of Mexico, but had risen to political prominence by his military skills on the battlefield but importantly he had chosen the correct side of decisive splits since 1913. When he was chosen as the presidential candidate in 1934, no one expected him to be anything other than being loyal to Calles, the "Jefe Máximo", and power behind the presidency since 1929.  As the PNR's candidate, Cárdenas's election was a foregone conclusion. It was politically impossible for his patron, Calles, to serve as president again, but he continued to dominate Mexico after his presidency (1924–28) through what were considered "puppet" administrations in a period known as the Maximato. After two of his hand-picked men held office, the PNR balked in 1932 at supporting his first choice, Manuel Pérez Treviño. Instead, they selected Cárdenas as the presidential candidate. Calles agreed, believing he could control Cárdenas as he had controlled his predecessors. Not only had Cárdenas been associated with Calles for two decades, but he had prospered politically with Calles' patronage. As expected, Cárdenas won handily, officially winning over 98 percent of the vote.

Six-Year Plan and presidential campaign.

Cárdenas ran on the Six Year Plan for social and political reform that the party drafted under Calles's direction. Such a multiyear program was patterned after the just-completed Five Year Plan of the Soviet Union. The Six-Year Plan (to span the presidential term 1934–40) was a patchwork of proposals from a variety of participants, but the driving force behind it was Calles, who had given a speech in May 1933, saying that the "Mexican Revolution had failed in most of its important objectives," and that a plan needed to implement its objectives. Interim President Abelardo L. Rodríguez did not get his cabinet's approval for the plan in 1933, so that Calles's next move was to present it in draft form

Presidency, 1934–1940.

Cabinet.

when he was first in office included Calles family members, his oldest son Rodolfo at the Secretariat of Communications and Public Works (1934–35); Aarón Sáenz Garza, the brother-in-law of Calles's second son, Plutarco Jr. ("Aco"), was appointed the administrator for Mexico City (1934–35), a cabinet-level position. Others with loyalty to Calles were radical Tomás Garrido Canabal at the Secretariat

Presidential style.

Cárdenas's first action after taking office late in 1934 was to have his presidential salary cut in half. He became the first occupant of the official presidential residence of Los Pinos. He had the previous residence, the ostentatious Chapultepec Castle, turned into the National Museum of History. In a move that struck at the financial interests

Policies in office.

After being elected and assuming office, Cárdenas led the Congress in condemning Calles's persecution of the Catholic Church in Mexico. He ousted Calles and exiled him in 1936 as he consolidated power in his own right, ending the so-called Maximato with Calles being the power behind the presidency. Cárdenas had Calles and twenty of his corrupt associates arrested and deported to the United States. The majority of the

Land reform and the peasantry.

During Cárdenas' presidency, the government enacted land reform that was "sweeping, rapid, and, in some respects, innovative". He redistributed large commercial haciendas, some 180,000 km of land to peasants. With the powers of Article 27 of the Mexican constitution, he created agrarian collectives, or ejidos, which in early twentieth-century Mexico were an not a typical form of landholding. Two high-profile regions of expropriation for Cárdenas's agrarian reform were in the productive cotton-growing region in northern Mexico, known as La Laguna, the other was in Yucatán, where the economy was dominated by henequen production. Other areas that saw significant land reform were Baja California and Sonora in northern Mexico

Labor.

The other key sector of reform was industrial labor. Article 123 of the 1917 Constitution had empowered labor in an unprecedented way, guaranteeing worker rights such as the eight-hour day and the right to strike, but in a more comprehensive fashion, Article 123 signaled that the Mexican state was on the side of labor. A labor organization already existed when Cárdenas took office, the CROM union of Luis Morones. Morones was forced out of his cabinet post in Calles's government and the CROM declined in power and influence, with major defections of Mexico City unions, one of which was led by socialist Vicente Lombardo Toledano. Cárdenas promoted

Education.

During the Calles Maximato, Mexican education policies were directed at curtailing the cultural influence of the Catholic Church by introducing sex education and leftist ideology via socialist education, and generally aiming to create a national civic culture. Cárdenas as a presidential candidate, under the patronage of fierce anticlerical Calles, was in favor of such policies. The opposition to socialist education by the Catholic Church as an institution and

Indigenismo.

Cárdenas created the new cabinet-level Department of Indigenous Affairs ("Departamento de Asuntos Indígenas") in 1936, with Graciano Sánchez, an "agrarista" leader in charge. After a controversy at the DAI, Sánchez was replaced by a scholar, Prof. Luis Chávez Orozco. Cárdenas was influenced by an advocate of indigenismo, Moisés Sáenz, who earned a doctorate in education from Columbia University and had held a position in the Calles administration in the Secretariat of Public Education (SEP). Although initially an assimilationist for Mexico's indigenous, he shifted his perspective after a period of residence in a Purépecha village, which he published

Women's suffrage.

Cárdenas had pushed for women's suffrage in Mexico, responding to the pressure from women activists and from the political climate that emphasized equality of citizens. Mexico was not alone in Latin America in not enfranchising women, but in 1932, both Brazil and Uruguay had extended suffrage to women, and Ecuador had also done so. Women had made a significant contribution to the Mexican Revolution, but had not made gains in the postrevolutionary phase as women. Women who were members of the National Peasants Confederation ("Confederación Nacional Campesina") or the Confederation of Mexican Workers ("Confederación de Trabajadores Mexicanos") were by virtue of their membership umbrella organizations were members of Cárdenas's reorganized party, the Party of the Mexican Revolution or PRM, done in 1938. In practice, however, women were marginalized from power. Women could not stand for national or local governmental elections or vote. The Constitution of 1917 did not explicitly address women's rights and so to enfranchise women required a constitutional amendment. The amendment itself was simple and brief, specifying that "mexicanos" referred to

Partido de la Revolución Mexicana.

The Partido de la Revolución Mexicana (PRM) came into being on March 30, 1938 after the party founded in 1929 by Calles, the Partido Nacional Revolucionario (PNR), was dissolved. Cárdenas's PRM was reorganized again in 1946 as the Institutional Revolutionary Party. Calles founded the PNR in the wake of President-elect Obregón's assassination in order to create some way for revolutionary leaders to maintain order and power. Calles could not be re-elected as president, but did hold power through the newly created party. Often called the "official party", it "was created as a cartel to control localized political machines and interests."  When Cárdenas ran as

1938 oil expropriation.

Cárdenas had had dealings with the oil industry in the Huasteca in his capacity as military commander there. Ongoing issues with the foreign-owned companies and the Mexican petroleum workers' organization became increasingly tense. Early in his presidency, he declared that a previous agreement between companies and the government "was not in harmony with the basic principle of Article 27 of the Constitution." In 1936, the 18,000 member oil workers' union forced oil companies to sign the first-ever collective bargaining agreement.

Spanish Civil War and refugees in Mexico.

Cárdenas supported the Republican government of Spain against right-wing general Francisco Franco's forces during the Spanish Civil War. Franco was given support by Germany and Italy. Mexico's support of the Republican government was "by selling arms to the Republican army, underwriting arms purchases from third parties, supporting the Republic in the League of Nations, providing food, shelter and education for children orphaned during the Spanish Civil War." Although Mexico's efforts in the Spanish Civil War were not enough to save the Spanish Republic, it did provide a place of exile for as many as 20,000-40,000 Spanish refugees. Among those who reached Mexico were distinguished intellectuals who left a

Relations with Latin America.

Mexico's most important relations with foreign countries during the Cárdenas presidency was the United States, but Cárdenas attempted to influence fellow Latin American nations viable formal

Other presidential actions.

The development bank, was founded during his term as president. Although not extensively active during that period, in the post-World War II era of the Mexican Miracle, the bank was an important tool in government industrialization projects.  Cárdenas became known for his progressive program of building roads and schools and promoting education, gaining Congressional approval to allocate twice as

Failed Saturnino Cedillo revolt, 1938–1939.

The last military revolt in Mexico was that of Saturnino Cedillo, a regional caudillo and former revolutionary general whose power base was in the state of San Luis Potosí. Cedillo was a supporter of Calles and had participated in the formation of the Partido Nacional Revolucionario. He was a "paradigmatic figure," acting as a strong leader in his region and mediating between the federal government and his local power base. As a powerbroker with demonstrated military and political skills, he had a great deal of autonomy in San Luis Potosí, serving a term as governor (1927–32), but then modeling Calles's Maximato was the power behind the governorship. Cedillo supported

Other political opposition to Cárdenas.

There was more organized and ideological opposition to Cárdenas. Right-wing political groups opposed Cárdenas's policies, including the National Synarchist Union (UNS), a popular, pro-Catholic,

Presidential election of 1940.

In the elections of 1940, Cárdenas, hoping to prevent another uprising or even "an outright counter-revolution throughout the Republic" by those opposed to his leftist policies, endorsed the PRM nominee Manuel Ávila Camacho, a moderate conservative. "Obregonista" Francisco Múgica would have been Cárdenas's ideological heir, and he had played an important role in the Revolution, the leader of the left-wing faction that successfully placed key language in the Constitution of 1917, guaranteeing the rights of labor. Múgica had known Cárdenas personally since 1926 when the two were working in Veracruz. Múgica had served in Cárdenas's cabinet as Secretary of the National Economy and as Secretary of the Ministry of Communications and Public Works. In those positions, Múgica made sure the federal government pursued social goals; Múgica was considered "the social conscience of Cardenismo." Múgica resigned his cabinet post to be a candidate for the 1940 presidential election. However, the political system was not one of open competition among candidates, although the PRM's rules required an open convention to select the candidate. Cárdenas established the unwritten rule that the president chose his successor. Cárdenas chose political unknown Manuel Ávila Camacho, far more centrist than Múgica, as the

Post-presidency.

After his presidential term that ended December 1, 1940, Cárdenas served as Mexico's Minister of War 1942–1945, when Mexico was a solid participant in World War II, which reassured Mexican nationalists concerned about a close alliance with the United States.  It has been said that Cárdenas was the only president associated with the Institutional Revolutionary Party (PRI) who did not use the office to make himself wealthy. He retired to a modest home by Lake Pátzcuaro, Michoacán, and worked the rest of his life supervising irrigation projects and promoting free medical clinics and education for the nation's poor. He also continued to speak out about international political issues and in favor of greater democracy and human rights in Latin America and elsewhere. For example, he was one of the participants in the Russell Tribunal for investigating war crimes in Vietnam. Although Cárdenas did not play the role that Calles had as the power behind the presidency, Cárdenas did exert influence on the PRI and in Mexican politics. He opposed the candidacy of Miguel Alemán Valdés for president in 1952, opposed the Vietnam War, and opposed the U.S. policy toward Cuba after the 1959 Cuban Revolution.  Cárdenas was not happy with the rightward shift of Mexican presidents, starting with the presidency of Miguel Alemán (1946-1952). During the presidency of Adolfo López Mateos (1958-1964), Cárdenas emerged from retirement and pressed the president toward leftist stances. With the triumph of the Cuban Revolution in January 1959, Cárdenas among others in Latin America who saw the hope of young revolution. Mexico was run by party that claimed the legacy of the Mexican Revolution but had turned away from revolutionary ideals. Cárdenas went to Cuba in July 1959 and

Honors.

In his honor, his name was given to a number of cities, towns, and a municipality in Mexico, including Lázaro Cárdenas, Michoacán, the municipality of Lázaro Cárdenas, Quintana Roo, Lázaro Cárdenas, Jalisco, and other smaller communities. A major on the Nazas River named for him was inaugurated in 1946. There are also many streets that have been named after

Legacy.

President Cárdenas and his administration are given credit by socialists for expanding the distribution of land to the peasants, establishing new welfare programs for the poor, and nationalizing the railroad and petroleum industries, including the oil company that Cárdenas founded, Petróleos Mexicanos. Toward the end of his presidency, unhappy landowners and foreign capitalists began to challenge his programs and his power. His choice of his close associate Manuel Ávila Camacho rather than a candidate with a distinguished record as a revolutionary leader was displeasing to many, and occasioned a possible military revolt.  The party that Cárdenas founded, the Partido de la Revolución Mexicana (PRM), established the basic structure of sectoral representation of important groups, a structure retained by its successor in 1946, the PRI. The PRI continued in power until 2000. This is attributed by some to electoral fraud and coercion. This legacy led his son, Cuauhtémoc Cárdenas, to form the Democratic Revolution Party (PRD) to contest the 1988 presidential election. Since that year, the PRD has become one of the three major parties in Mexico, gaining working class support that was previously enjoyed by the PRI.  In his "Political Testament", written the year before his death and published posthumously, he acknowledged that his regime had failed to make the changes in distribution of political power and corruption that were the basis for his presidency and the revolution. He expressed his dismay in the fact that some people and groups were making themselves rich to the detriment of the mainly poor majority. It was said of Cárdenas in a eulogy that "he was the greatest figure produced by the revolution... an authentic revolutionary who aspired to the greatness of his country, not personal aggrandizement."  Philippine President Ramon Magsaysay patterned his people–oriented government on the principles which he found in a biography of Cárdenas written by William Cameron Townsend.

Lázaro Cárdenas del Río (Local ; May 21, 1895 – October 19, 1970) was a general in the Constitutionalist Army during the Mexican Revolution and a statesman who served as President of Mexico between 1934 and 1940. He is best known for nationalization of the oil industry in 1938 and the creation of Pemex, the government oil company. He also revived agrarian reform in Mexico, expropriating large landed estates and distributing land to small holders in collective holdings (ejidos).

Lázaro Cárdenas del Río, né le à Jiquilpan (Michoacán) et mort le à Mexico, est un homme d’État mexicain. Il fut président du Mexique de 1934 à 1940.


Etymology.

Hephaestus is probably associated with the Linear B (Mycenaean Greek) inscription, "A-pa-i-ti-jo", found at Knossos. The inscription indirectly attests his worship at that time because it is believed that it reads the theophoric name "(H)āphaistios", or "Hāphaistion". The Greek theonym "Hēphaistos" is most likely of Pre-Greek origin, as the form without "-i-" (Attic "Hēphastos") shows a typical Pre-Greek variation and points to an original "s".

Epithets.

Hephaestus is given many epithets. The meaning of each epithet is:

Mythology.

Craft of Hephaestus.

Hephaestus had his own palace on Olympus, containing his workshop with anvil and twenty bellows that worked at his bidding. Hephaestus crafted much of the magnificent equipment of the gods, and almost any finely wrought metalwork imbued with powers that appears in Greek myth is said to have been forged by Hephaestus. He designed Hermes' winged helmet and sandals, the Aegis breastplate, Aphrodite's famed girdle, Agamemnon's staff of office, Achilles' armour, Diomedes' cuirass, Heracles' bronze clappers, Helios' chariot, the shoulder of Pelops, and Eros's bow and arrows. In later accounts, Hephaestus worked with the help of the Cyclopes—among them his assistants in the forge, Brontes, Steropes and Arges.  Hephaestus built automatons of metal to work for him. This included tripods that walked to and from Mount Olympus. He gave to the blinded Orion his apprentice Cedalion as a guide. In some versions of the myth, Prometheus stole the fire that he gave to man from Hephaestus's forge. Hephaestus also created the gift that the gods gave to man, the woman Pandora and her pithos. Being a skilled blacksmith, Hephaestus created all the thrones in the Palace of Olympus.  The Greek myths and the Homeric poems sanctified in stories that Hephaestus had a special power to produce motion. He made the golden and silver lions and dogs at the entrance of the palace of Alkinoos in such a way that they could bite the invaders. The Greeks maintained in their civilization an animistic idea that statues are in some sense alive. This kind of art and the animistic belief goes back to the Minoan period, when Daedalus, the builder of the labyrinth, made images which moved of their own accord. A statue of the god was somehow the god himself, and the image on a man's tomb indicated somehow his presence.

Parentage.

In the account of Attic vase painters, Hephaestus was present at the birth of Athena and wields the axe with which he split Zeus' head to free her. In the latter account, Hephaestus is there represented as older than Athena, so the mythology of Hephaestus is inconsistent in this respect.

Fall from Olympus.

In one branch of Greek mythology, Hera ejected Hephaestus from the heavens because he was "shrivelled of foot". He fell into the ocean and was raised by Thetis (mother of Achilles and one of the 50 Nereids) and the Oceanid Eurynome.  In another account, Hephaestus, attempting to rescue his mother from Zeus' advances, was flung down from the heavens by Zeus. He fell for an entire day and landed on the island of Lemnos, where he was cared for and taught to be a master craftsman by the Sintians – an ancient tribe native to that island. Later writers describe his lameness as the consequence of his second fall, while Homer makes him lame and weak from his birth.

Return to Olympus.

Hephaestus was one of the Olympians to have returned to Olympus after being exiled.  In an archaic story, Hephaestus gained revenge against Hera for rejecting him by making her a magical golden throne, which, when she sat on it, did not allow her to stand up. The other gods begged Hephaestus to return to Olympus to let her go, but he refused, saying "I have no mother".  At last, Dionysus fetched him, intoxicated him with wine, and took the subdued smith back to Olympus on the back of a mule accompanied by revelers – a scene that sometimes appears on painted pottery of Attica and of Corinth. In the painted scenes, the padded dancers and phallic figures of the Dionysan throng leading the mule show that the procession was a part of the dithyrambic celebrations that were the forerunners of the satyr plays of fifth century Athens.  The theme of the "return of Hephaestus", popular among the Attic vase-painters whose wares were favored among the Etruscans, may have introduced this theme to Etruria. In the vase-painters' portrayal of the procession, Hephaestus was mounted on a mule or a horse, with Dionysus holding the bridle and carrying Hephaestus' tools (including a double-headed axe).  The traveller Pausanias reported seeing a painting in the temple of Dionysus in Athens, which had been built in the 5th century but may have been decorated at any time before the 2nd century CE. When Pausanias saw it, he said:

Consorts and children.

According to most versions, Hephaestus's consort is Aphrodite, who is unfaithful to Hephaestus with a number of gods and mortals, including Ares. However, in Book XVIII of Homer's "Iliad", the consort of Hephaestus is a lesser Aphrodite, Charis ("the grace") or Aglaia ("the glorious") – the youngest of the Graces, as Hesiod calls her. In Athens, there is a Temple of Hephaestus, the "Hephaesteum" (miscalled the "Theseum") near the agora. An Athenian founding myth tells that the city's patron goddess, Athena, refused a union with Hephaestus. Pseudo-Apollodorus records an archaic legend, which claims that Hephaestus once attempted to rape Athena, but she pushed him away, causing him to ejaculate on her thigh. Athena wiped the semen off using a tuft of wool, which she tossed into the dust, impregnating Gaia and causing her to give birth to Erichthonius, whom Athena adopted as her own child. The Roman mythographer Hyginus records a similar story in which Hephaestus demanded Zeus to let him marry Athena since he was the one who had smashed open Zeus's skull, allowing Athena to be born. Zeus agreed to this and Hephaestus and Athena were married, but, when Hephaestus was about to consummate the union, Athena vanished from the bridal bed, causing him to ejaculate on the floor, thus impregnating Gaia with Erichthonius.  On the island of Lemnos, Hephaestus' consort was the sea nymph Cabeiro, by whom he was the father of two metalworking gods named the Cabeiri. In Sicily, his consort was the nymph Aetna, and his sons were two gods of Sicilian geysers called Palici. With Thalia, Hephaestus was sometimes considered the father of the Palici.  Hephaestus fathered several children with mortals and immortals alike. One of those children was the robber Periphetes.  This is the full list of his consorts and children according to the various accounts:  In addition, the Romans claim their equivalent god, Vulcan, to have produced the following children:

Hephaestus and Aphrodite.

Though married to Hephaestus, Aphrodite had an affair with Ares, the god of war. Eventually, Hephaestus discovered Aphrodite’s affair through Helios, the all-seeing Sun, and planned a trap during one of their trysts. While Aphrodite and Ares lay together in bed, Hephaestus ensnared them in an unbreakable chain-link net so small as to be invisible and dragged them to Mount Olympus to shame them in front of the other gods for retribution.  The gods laughed at the sight of these naked lovers, and Poseidon persuaded Hephaestus to free them in return for a guarantee that Ares would pay the adulterer's fine. Hephaestus states in "The Odyssey" that he would return Aphrodite to her father and demand back his bride price.  The Thebans told that the union of Ares and Aphrodite produced Harmonia. However, of the union of Hephaestus with Aphrodite, there was no issue unless Virgil was serious when he said that Eros was their child. Later authors explain this statement by saying that Eros was sired by Ares but passed off to Hephaestus as his own son.  Hephaestus was somehow connected with the archaic, pre-Greek Phrygian and Thracian mystery cult of the Kabeiroi, who were also called the "Hephaistoi", "the Hephaestus-men", in Lemnos. One of the three Lemnian tribes also called themselves Hephaestion and claimed direct descent from the god.

Hephaestus and Athena.

Hephaestus is to the male gods as Athena is to the females, for he gives skill to mortal artists and was believed to have taught men the arts alongside Athena. He was nevertheless believed to be far inferior to the sublime character of Athena. At Athens they had temples and festivals in common. Both were believed to have great healing powers, and Lemnian earth (terra Lemnia) from the spot on which Hephaestus had fallen was believed to cure madness, the bites of snakes, and haemorrhage, and priests of Hephaestus knew how to cure wounds inflicted by snakes.  He was represented in the temple of Athena Chalcioecus (Athena of the Bronze House) at Sparta, in the act of delivering his mother; on the chest of Cypselus, giving Achilles's armour to Thetis; and at Athens there was the famous statue of Hephaestus by Alcamenes, in which his lameness was only subtly portrayed. The Greeks frequently placed small dwarf-like statues of Hephaestus near their hearths, and these figures are the oldest of all his representations. During the best period of Grecian art he was represented as a vigorous man with a beard, and is characterized by his hammer or some other crafting tool, his oval cap, and the chiton.  Athena is sometimes thought to be "the ‘soul-mate’ of [Hephaestus]. Yet a kind of cloudy mysteriousness shrouds their relationship; no single tradition was ever clearly established on this subject, and so what confronts us is a blurred image based on rumors and conflicting reports." Nonetheless, he "seeks impetuously and passionately to make love to Athena: at the moment of climax she pushes him aside, and his semen falls to the earth where it impregnates Gaia."

Volcano god.

Hephaestus was associated by Greek colonists in southern Italy with the volcano gods Adranus (of Mount Etna) and Vulcanus of the Lipari islands. The first-century sage Apollonius of Tyana is said to have observed, "there are many other mountains all over the earth that are on fire, and yet we should never be done with it if we assigned to them giants and gods like Hephaestus".

Other mythology.

In the Trojan war, Hephaestus sided with the Greeks, but was also worshiped by the Trojans and saved one of their men from being killed by Diomedes. Hephaestus’ favourite place in the mortal world was the island of Lemnos, where he liked to dwell among the Sintians, but he also frequented other volcanic islands such as Lipara, Hiera, Imbros and Sicily, which were called his abodes or workshops.  The epithets and surnames by which Hephaestus is known by the poets generally allude to his skill in the plastic arts or to his figure or lameness. The Greeks frequently placed small dwarf-like statues of Hephaestus near their hearths, and these figures are the oldest of all his representations.  At the marriage of Peleus and Thetis he gave a knife as a wedding present.

Symbolism.

Hephaestus was sometimes portrayed as a vigorous man with a beard and was characterized by his hammer or some other crafting tool, his oval cap, and the chiton.  Hephaestus is described in mythological sources as "lame" (), and "halting" (). He was depicted with crippled feet and as misshapen, either from birth or as a result of his fall from Olympus. In vase paintings, Hephaestus is usually shown lame and bent over his anvil, hard at work on a metal creation, and sometimes with his feet back-to-front: "Hephaistos amphigyēeis". He walked with the aid of a stick. The Argonaut Palaimonius, "son of Hephaestus" (i.e. a bronze-smith) was also lame.  Other "sons of Hephaestus" were the Cabeiri on the island of Samothrace, who were identified with the crab ("karkinos") by the lexicographer Hesychius. The adjective "karkinopous" ("crab-footed") signified "lame", according to Detienne and Vernant. The Cabeiri were also lame.  In some myths, Hephaestus built himself a "wheeled chair" or chariot with which to move around, thus helping him overcome his lameness while demonstrating his skill to the other gods. In the "Iliad" 18.371, it is stated that Hephaestus built twenty bronze wheeled tripods to assist him in moving around.  Hephaestus’s ugly appearance and lameness is taken by some to represent peripheral neuropathy and skin cancer resulting from arsenicosis caused by arsenic exposure from metalworking. Bronze age smiths added arsenic to copper to produce harder arsenical bronze, especially during periods of tin scarcity. Many Bronze Age smiths would have suffered from chronic arsenic poisoning as a result of their livelihood. Consequently, the mythic image of the lame smith is widespread. As Hephaestus was an iron-age smith, not a bronze-age smith, the connection is one from ancient folk memory.

Comparative mythology.

Parallels in other mythological systems for Hephaestus's symbolism include:

Cities and places.

Solinus wrote that the Lycians dedicated a city to Hephaestus and called it Hephaestia. The Hephaestia in Lemnos was named after the god. In addition, the whole island of Lemnos was sacred to Hephaestus.  Pausanias wrote that the Lycians in Patara had a bronze bowl in their temple of Apollo, saying that Telephus dedicated it and Hephaestus made it.  The island Thermessa, between Lipari and Sicily was also called Hiera of Hephaestus (ἱερὰ Ἡφαίστου), meaning sacred place of Hephaestus in Greek.

Minor planet.

The minor planet 2212 Hephaistos discovered in 1978 by Soviet astronomer Lyudmila Chernykh was named in Hephaestus' honour.

Sooty grunter.

The sooty grunter ("Hephaestus fuliginosus"), a dark, typically sooty-coloured freshwater fish of the family Terapontidae found in northern Australia, is named after Hephaestus.

Stones.

Pliny the Elder wrote that at Corycus there was a stone which was called Hephaestitis or Hephaestus stone. According to Pliny, the stone was red and was reflecting images like a mirror, and when boiling water poured over it cooled immediately or alternatively when it placed in the sun it immediately set fire to a parched substance.

Hephaestus (; eight spellings; "Hēphaistos") is the Greek god of blacksmiths, metalworking, carpenters, craftsmen, artisans, sculptors, metallurgy, fire (compare, however, with Hestia), and volcanoes. Hephaestus' Roman equivalent is Vulcan. In Greek mythology, Hephaestus was either the son of Zeus and Hera or he was Hera's parthenogenous child. He was cast off Mount Olympus by his mother because of his deformity or, in another account, by Zeus for protecting Hera from his advances.

Dans la mythologie grecque, Héphaïstos ou Héphaestos (en grec ancien ) est le dieu du feu, de la forge, de la métallurgie et des volcans.


Properties.

Every entire function "f"("z") can be represented as a power series  that converges everywhere in the complex plane, hence uniformly on compact sets. The radius of convergence is infinite, which implies that  or  Any power series satisfying this criterion will represent an entire function.  If (and only if) the coefficients of the power series are all real then the function evidently takes real values for real arguments, and the value of the function at the complex conjugate of "z" will be the complex conjugate of the value at "z". Such functions are sometimes called self-conjugate (the conjugate function, formula_4, being given by formula_5  If the real part of an entire function is known in a neighborhood of a point then both the real and imaginary parts are known for the whole complex plane, up to an imaginary constant. For instance, if the real part is known in a neighborhood of zero, then we can find the coefficients for "n" > 0 from the following derivatives with respect to a real variable "r":  (Likewise, if the imaginary part is known in a neighborhood then the function is determined up to a real constant.) In fact, if the real part is known just on an arc of a circle, then the function is determined up to an imaginary constant. (For instance, if the real part is known on part of the unit circle, then it is known on the whole unit circle by analytic extension, and then the coefficients of the infinite series are determined from the coefficients of the Fourier series for the real part on the unit circle.) Note however that an entire function is not determined by its real part on all curves. In particular, if the real part is given on any curve in the complex plane where the real part of some other entire function is zero, then any multiple of that function can be added to the function we are trying to determine. For example, if the curve where the real part is known is the real line, then we can add "i" times any self-conjugate function. If the curve forms a loop, then it is determined by the real part of the function on the loop since the only functions whose real part is zero on the curve are those that are everywhere equal to some imaginary number.  The Weierstrass factorization theorem asserts that any entire function can be represented by a product involving its zeroes (or "roots").  The entire functions on the complex plane form an integral domain (in fact a Prüfer domain). They also form a commutative unital associative algebra over the complex numbers.  Liouville's theorem states that any bounded entire function must be constant. Liouville's theorem may be used to elegantly prove the fundamental theorem of algebra.  As a consequence of Liouville's theorem, any function that is entire on the whole Riemann sphere (complex plane "and" the point at infinity) is constant. Thus any non-constant entire function must have a singularity at the complex point at infinity, either a pole for a polynomial or an essential singularity for a transcendental entire function. Specifically, by the Casorati–Weierstrass theorem, for any transcendental entire function "f" and any complex "w" there is a sequence formula_7 such that  Picard's little theorem is a much stronger result: any non-constant entire function takes on every complex number as value, possibly with a single exception. When an exception exists, it is called a lacunary value of the function. The possibility of a lacunary value is illustrated by the exponential function, which never takes on the value 0. One can take a suitable branch of the logarithm of an entire function that never hits 0, so that this will also be an entire function (according to the Weierstrass factorization theorem). The logarithm hits every complex number except possibly one number, which implies that the first function will hit any value other than 0 an infinite number of times. Similarly, a non-constant, entire function that does not hit a particular value will hit every other value an infinite number of times.  Liouville's theorem is a special case of the following statement:

Growth.

Entire functions may grow as fast as any increasing function: for any increasing function "g": [0,∞) → [0,∞) there exists an entire function "f" such that "f"("x") > "g"(|"x"|) for all real "x". Such a function "f" may be easily found of the form:  for a constant "c" and a strictly increasing sequence of positive integers "n". Any such sequence defines an entire function "f"("z"), and if the powers are chosen appropriately we may satisfy the inequality "f"("x") > "g"(|"x"|) for all real "x". (For instance, it certainly holds if one chooses "c" := "g"(2) and, for any integer formula_14 one chooses an even exponent formula_15 such that formula_16).

Order and type.

The order (at infinity) of an entire function formula_17 is defined using the limit superior as:  where "B" is the disk of radius "r" and formula_19 denotes the supremum norm of formula_17 on "B". The order is a non-negative real number or infinity (except when formula_21 for all "z"). In other words, the order of formula_17 is the infimum of all "m" such that:  The example of formula_24 shows that this does not mean "f"("z") = O(exp(|"z"|)) if formula_17 is of order "m".  If formula_26 one can also define the type:  If the order is 1 and the type is "σ", the function is said to be "of exponential type "σ"". If it is of order less than 1 it is said to be of exponential type 0.  If  then the order and type can be found by the formulas  Let formula_30 denote the "n" derivative of "f", then we may restate these formulas in terms of the derivatives at any arbitrary point "z":  The type may be infinite, as in the case of the reciprocal gamma function, or zero (see example below under #Order 1).

Examples.

Here are some examples of functions of various orders:

Order ρ.

For arbitrary positive numbers "ρ" and "σ" one can construct an example of an entire function of order "ρ" and type "σ" using:

Order 1/4.

where

Order 1/3.

where

Genus.

Entire functions of finite order have Hadamard's canonical representation:  where formula_41 are those roots of formula_42 that are not zero (formula_43), formula_44 is the order of the zero of formula_42 at formula_46 (the case formula_47 being taken to mean formula_48), formula_49 a polynomial (whose degree we shall call formula_50), and formula_51 is the smallest non-negative integer such that the series  converges. The non-negative integer formula_53 is called the genus of the entire function formula_42.  If the order ρ is not an integer, then formula_55 is the integer part of formula_56. If the order is a positive integer, then there are two possibilities: formula_57 or formula_58.  For example, formula_59 and formula_60 are entire functions of genus "1".

Other examples.

According to J. E. Littlewood, the Weierstrass sigma function is a 'typical' entire function. This statement can be made precise in the theory of random entire functions: the asymptotic behavior of almost all entire functions is similar to that of the sigma function. Other examples include the Fresnel integrals, the Jacobi theta function, and the reciprocal Gamma function. The exponential function and the error function are special cases of the Mittag-Leffler function. According to the fundamental theorem of Paley and Wiener, Fourier transforms of functions (or distributions) with bounded support are entire functions of order "1" and finite type.  Other examples are solutions of linear differential equations with polynomial coefficients. If the coefficient at the highest derivative is constant, then all solutions of such equations are entire functions. For example, the exponential function, sine, cosine, Airy functions and Parabolic cylinder functions arise in this way. The class of entire functions is closed with respect to compositions. This makes it possible to study dynamics of entire functions.  An entire function of the square root of a complex number is entire if the original function is even, for example formula_61.  If a sequence of polynomials all of whose roots are real converges in a neighborhood of the origin to a limit which is not identically equal to zero, then this limit is an entire function. Such entire functions form the Laguerre–Pólya class, which can also be characterized in terms of the Hadamard product, namely, "f" belongs to this class if and only if in the Hadamard representation all "z" are real, "p" ≤ 1, and "P"("z") = "a" + "bz" + "cz", where "b" and "c" are real, and "c" ≤ 0. For example, the sequence of polynomials  converges, as "n" increases, to exp(−("z"−"d")). The polynomials  have all real roots, and converge to cos("z"). The polynomials  also converge to cos("z"), showing the buildup of the Hadamard product for cosine.

In complex analysis, an entire function, also called an integral function, is a complex-valued function that is holomorphic at all finite points over the whole complex plane. Typical examples of entire functions are polynomials and the exponential function, and any finite sums, products and compositions of these, such as the trigonometric functions sine and cosine and their hyperbolic counterparts sinh and cosh, as well as derivatives and integrals of entire functions such as the error function. If an entire function "f"("z") has a root at "w", then "f"("z")/("z−w"), taking the limit value at "w", is an entire function. On the other hand, neither the natural logarithm nor the square root is an entire function, nor can they be continued analytically to an entire function.

En analyse complexe, une fonction entière est une fonction holomorphe définie sur tout le plan complexe. C'est le cas notamment de la fonction exponentielle complexe, des fonctions polynomiales et de leurs combinaisons par composition, somme et produit, telles que "sinus", "cosinus" et les fonctions hyperboliques.