Irrigation is the application of controlled amounts of water to plants at needed intervals. Irrigation helps to grow agricultural crops, maintain landscapes, revegetate disturbed soils in dry areas and during periods of less than average rainfall. Irrigation has other uses in crop production, including frost protection, suppressing weed growth in grain fields and preventing soil consolidation. In contrast, agriculture that relies only on direct rainfall is referred to as rain-fed or dry land farming. Irrigation systems are used for cooling livestock, dust suppression, disposal of sewage, in mining. Irrigation is studied together with drainage, the removal of surface and sub-surface water from a given area. Irrigation has been a central feature of agriculture for over 5,000 years and is the product of many cultures, it was the basis for economies and societies across the globe, from Asia to the Southwestern United States. Archaeological investigation has found evidence of irrigation in areas lacking sufficient natural rainfall to support crops for rainfed agriculture.
The earliest known use of the technology dates to the 6th millennium BCE in Khuzistan in the south-west of present-day Iran. Irrigation was used as a means of manipulation of water in the alluvial plains of the Indus valley civilization, the application of it is estimated to have begun around 4500 BC and drastically increased the size and prosperity of their agricultural settlements; the Indus Valley Civilization developed sophisticated irrigation and water-storage systems, including artificial reservoirs at Girnar dated to 3000 BCE, an early canal irrigation system from c. 2600 BCE. Large-scale agriculture was practiced, with an extensive network of canals used for the purpose of irrigation. Farmers in the Mesopotamian plain used irrigation from at least the third millennium BCE, they developed perennial irrigation watering crops throughout the growing season by coaxing water through a matrix of small channels formed in the field. Ancient Egyptians practiced basin irrigation using the flooding of the Nile to inundate land plots, surrounded by dykes.
The flood water remained until the fertile sediment had settled before the engineers returned the surplus to the watercourse. There is evidence of the ancient Egyptian pharaoh Amenemhet III in the twelfth dynasty using the natural lake of the Faiyum Oasis as a reservoir to store surpluses of water for use during dry seasons; the lake swelled annually from the flooding of the Nile. The Ancient Nubians developed a form of irrigation by using a waterwheel-like device called a sakia. Irrigation began in Nubia some time between the third and second millennia BCE, it depended upon the flood waters that would flow through the Nile River and other rivers in what is now the Sudan. In sub-Saharan Africa irrigation reached the Niger River region cultures and civilizations by the first or second millennium BCE and was based on wet-season flooding and water harvesting. Evidence of terrace irrigation occurs in pre-Columbian America, early Syria and China. In the Zana Valley of the Andes Mountains in Peru, archaeologists have found remains of three irrigation canals radiocarbon-dated from the 4th millennium BCE, the 3rd millennium BCE and the 9th century CE.
These canals provide the earliest record of irrigation in the New World. Traces of a canal dating from the 5th millennium BCE were found under the 4th-millennium canal. Ancient Persia used irrigation as far back as the 6th millennium BCE to grow barley in areas with insufficient natural rainfall; the Qanats, developed in ancient Persia about 800 BCE, are among the oldest known irrigation methods still in use today. They are now found in the Middle East and North Africa; the system comprises a network of vertical wells and sloping tunnels driven into the sides of cliffs and of steep hills to tap groundwater. The noria, a water wheel with clay pots around the rim powered by the flow of the stream, first came into use at about this time among Roman settlers in North Africa. By 150 BCE the pots were fitted with valves to allow smoother filling as they were forced into the water; the irrigation works of ancient Sri Lanka, the earliest dating from about 300 BCE in the reign of King Pandukabhaya, under continuous development for the next thousand years, were one of the most complex irrigation systems of the ancient world.
In addition to underground canals, the Sinhalese were the first to build artificial reservoirs to store water. These reservoirs and canal systems were used to irrigate paddy fields, which require a lot of water to cultivate. Most of these irrigation systems still exist undamaged up to now, in Anuradhapura and Polonnaruwa, because of the advanced and precise engineering; the system was further extended during the reign of King Parakrama Bahu. The oldest known hydraulic engineers of China were Sunshu Ao of the Spring and Autumn period and Ximen Bao of the Warring States period, both of whom worked on large irrigation projects. In the Sichuan region belonging to the state of Qin of ancient China, the Dujiangyan Irrigation System devised by the Qin Chinese hydrologist and irrigation engineer Li Bing was built in 256 BCE to irrigate a vast area of farmland that today still supplies water. By the 2nd century AD, during the Han Dynasty, the Chinese used chain pumps which lifted water from a lower elevation to a higher one.
These were powered by manual foot-pedal, hydraulic waterwheels, or rotating mechanical wheels pulled by oxen. The water was used for public works, providing water for urban residential quarters and palace gardens, bu
Salt Lake Valley
Salt Lake Valley is a 500-square-mile valley in Salt Lake County in the north-central portion of the U. S. state of Utah. It contains Salt Lake City and many of its suburbs, notably Murray, South Jordan, West Jordan, West Valley City. Brigham Young said "this is the right place", when he and his fellow settlers moved into Utah after being driven out of several states; the Valley is surrounded in every direction except the northwest by steep mountains that at some points rise 7,100 feet from the valley floor's base elevation. It lies nearly encircled by the Wasatch Mountains on the east, the Oquirrh Mountains on the west, Traverse Ridge to the south and the Great Salt Lake on the northwest, with the peaks of Antelope Island visible; every entrance into the valley is narrow and congested. They include the Point of the Mountain to the south via the Jordan Narrows, a gap in the Traverse Mountains, narrow entrances between the Great Salt Lake and Oquirrh Mountains to the northwest and the Great Salt Lake and the Wasatch Mountains to the north, several canyons to the east including Parley's Canyon and Emigration Canyon.
Flowing from Utah Lake in Utah Valley in the south, the Jordan River runs north through a gap in the Traverse Mountains, bisecting the Valley before emptying into the Great Salt Lake. The Jordan River, along with numerous mountain streams and reservoirs, provides irrigation water to the growing Valley; the only areas that have not been urbanized in Salt Lake Valley are near the Great Salt Lake and in the far west and mid-southwest parts of the Valley, although those areas are beginning to experience the effects of the Salt Lake City urban area's rapid expansion. This southwestern expansion will be facilitated by the Mountain View Corridor; some experts are claiming. A company known as Kennecott Land, which owns the eastern foothills of the Oquirrhs in the western part of the valley drafted a plan that would develop the rest of the entire valley within 75 years, adding at least 500,000 residents; the first development, known as the Daybreak Community, has substantial portions completed but continues construction.
It will focus on transit-oriented development (it has service by TRAX light rail and will feature a ski resort in the Oquirrh Mountains and a university campus. Interstate 15 runs north to south through the middle-eastern portion of the Valley and Interstate 80 runs east to west in the northern quarter of the Valley from Parley's Canyon into Tooele County to the west; the Interstate 215 belt route, State Route 154, State Route 201, State Route 85 are major transportation routes. The Utah Transit Authority operates an extensive bus system across the Wasatch Front, including the Salt Lake Valley, in addition to three light rail lines in the Valley. A commuter rail line known as FrontRunner runs north to Pleasant View in Weber County and south to Provo in Utah County. Mormon Trail Salt Lake County, Utah
University of Illinois at Urbana–Champaign
The University of Illinois at Urbana–Champaign is a public research university in Illinois and the flagship institution of the University of Illinois System. Founded in 1867 as a land-grant institution, its campus is located in the twin cities of Champaign and Urbana; the University of Illinois at Urbana–Champaign is a member of the Association of American Universities and is classified as a R1 Doctoral Research University under the Carnegie Classification of Institutions of Higher Education, which denotes the highest research activity. In fiscal year 2017, research expenditures at Illinois totaled $642 million; the campus library system possesses the second-largest university library in the United States by holdings after Harvard University. The university hosts the National Center for Supercomputing Applications and is home to the fastest supercomputer on a university campus; the university contains 16 schools and colleges and offers more than 150 undergraduate and over 100 graduate programs of study.
The university holds 651 buildings on 6,370 acres and its annual operating budget in 2016 was over $2 billion. The University of Illinois at Urbana–Champaign operates a Research Park home to innovation centers for over 90 start-up companies and multinational corporations, including Abbott, AbbVie, Capital One, State Farm, Yahoo, among others; as of October 2018, 30 Nobel laureates, 2 Turing Award winners, 1 Fields medalist have been affiliated with the university as alumni, faculty members, or researchers. The University of Illinois named "Illinois Industrial University", was one of the 37 universities created under the first Morrill Land-Grant Act, which provided public land for the creation of agricultural and industrial colleges and universities across the United States. Among several cities, Urbana was selected in 1867 as the site for the new school. From the beginning, President John Milton Gregory's desire to establish an institution grounded in the liberal arts tradition was at odds with many state residents and lawmakers who wanted the university to offer classes based around "industrial education".
The university opened for classes on March 2, 1868, had two faculty members and 77 students. The Library, which opened with the school in 1868, started with 1,039 volumes. Subsequently, President Edmund J. James, in a speech to the board of trustees in 1912, proposed to create a research library, it is now one of the world's largest public academic collections. In 1870, the Mumford House was constructed as a model farmhouse for the school's experimental farm; the Mumford House remains the oldest structure on campus. The original University Hall was the fourth building built. In 1885, the Illinois Industrial University changed its name to the "University of Illinois", reflecting its agricultural and liberal arts curriculum. During his presidency, Edmund J. James is credited for building the foundation for the large Chinese international student population on campus. James established ties with China through the Chinese Minister to the United States Wu Ting-Fang. In addition, during James's presidency, class rivalries and Bob Zuppke's winning football teams contributed to campus morale.
Alma Mater, a prominent statue on campus created by alumnus Lorado Taft, was unveiled on June 11, 1929. It was established from donations by the Alumni Fund and the classes of 1923–1929. Like many Universities, the economic depression slowed expansion on the campus; the university replaced the original university hall with the Illini Union. After World War II, the university experienced rapid growth; the enrollment doubled and the academic standing improved. This period was marked by large growth in the Graduate College and increased federal support of scientific and technological research. During the 1950s and 1960s the university experienced the turmoil common on many American campuses. Among these were the water fights of the fifties and sixties. By 1967 the University of Illinois system consisted of a main campus in Champaign-Urbana and two Chicago campuses, Chicago Circle and Medical Center, people began using "Urbana–Champaign" or the reverse to refer to the main campus specifically; the university name changed to the "University of Illinois at Urbana–Champaign" around 1982, using the reverse of the used designation for the metropolitan area, "Champaign-Urbana".
The name change established a separate identity for the main campus within the University of Illinois system, which today includes campuses in Springfield and Chicago. In 1998, the Hallene Gateway Plaza was dedicated; the Plaza features the original sandstone portal of University Hall, the fourth building on campus. In recent years, state support has declined from 4.5% of the state's tax appropriations in 1980 to 2.28% in 2011, a nearly 50% decline. As a result, the university's budget has shifted away from relying on state support with nearly 84% of the budget now coming from other sources. On March 12, 2015, the Board of Trustees approved the creation of a medical school, being the first college created at Urbana–Champaign in over 60 years; the Carle-Illinois College of Medicine began classes in 2018. The main research and academic facilities are divided evenly between the twin cities of Urbana and Champaign, which form part of the Champaign–Urbana metropolitan area; the College of Agriculture and Environmental Sciences' research fields stretch south from Urbana and Champaign into Savoy and Champaign County.
Land reclamation known as reclamation, known as land fill, is the process of creating new land from oceans, riverbeds, or lake beds. The land reclaimed is known as reclamation land fill. In a number of other jurisdictions, including parts of the United States, the term "reclamation" can refer to returning disturbed lands to an improved state. In Alberta, for example, reclamation is defined by the provincial government as "The process of reconverting disturbed land to its former or other productive uses." In Oceania it is referred to as land rehabilitation. Land reclamation can be achieved with a number of different methods; the most simple method involves filling the area with large amounts of heavy rock and/or cement filling with clay and dirt until the desired height is reached. The process is called "infilling" and the material used to fill the space is called "infill". Draining of submerged wetlands is used to reclaim land for agricultural use. Deep cement mixing is used in situations in which the material displaced by either dredging or draining may be contaminated and hence needs to be contained.
Land dredging is another method of land reclamation. It is the removal of sediments and debris from the bottom of a body of water, it is used for maintaining reclaimed land masses as sedimentation, a natural process, fills channels and harbors naturally. Instances where the creation of new land was for the need of human activities. Notable examples include: Some of the coastlines of Saadiyat Island, in the UAE. Used for commercial purposes. Much of the coastlines of Mumbai, India, it took over 150 years to join the original Seven Islands of Bombay. These seven islands were lush, thickly wooded, dotted with 22 hills, with the Arabian Sea washing through them at high tide; the original Isle of Bombay was only 24 km long and 4 km wide from Dongri to Malabar Hill and the other six were Colaba, Old Woman's Island, Parel and Mazgaon.. Much of the coastlines of Mainland China, Hong Kong, North Korea and South Korea, it is estimated. Inland lowlands in the Yangtze valley, including the areas of important cities like Shanghai and Wuhan.
Much of the coastline of Karachi, Pakistan. The shore of Jakarta Bay. Land is reclaimed to create new housing areas and real estate properties, for the expanding city of Jakarta. So far, the largest reclamation project in the city is the creation of "Golf Island", still ongoing. A part of the Hamad International Airport in Qatar, around 36 square kilometres; the entire island of The Pearl-Qatar situated in Qatar. Haikou Bay, Hainan Province, where the west side of Haidian Island is being extended, off the coast of Haikou City, where new land for a marina is being created; the Cotai Strip in Macau, where most of the major casinos are located Nagoya Centrair Airport, Japan Incheon International Airport, Korea Beirut Central District, Lebanon The southern Chinese city of Shenzhen The shore of Manila Bay in the Philippines along Metro Manila, has attracted major developments such as the Mall of Asia Complex, Entertainment City and the Cultural Center of the Philippines Complex. The city-state of Singapore, where land is in short supply, is famous for its efforts on land reclamation.
The Palm Islands, The World and hotel Burj al-Arab off Dubai in the United Arab Emirates The Yas Island in Abu Dhabi, UAE. Hulhumalé Island, Maldives, it is one of the six divisions of Malé City. Giant Sea Wall Jakarta Colombo International Financial City, Sri Lanka Airport of Nice, France Large parts of the Netherlands Almost half of the microstate of Monaco Parts of Dublin, Ireland Most of Belfast Harbour and areas of Belfast, Northern Ireland Parts of Saint Petersburg, such as the Marine Facade Helsinki Barceloneta area, Barcelona, in Spain The port of Zeebrugge in Belgium The southwestern residential area in Brest, Belarus Majority of left-bank and some right-bank residential areas of Kiev were built on a reclaimed fens and floodplains of the Dnieper river. Most of Fontvieille, Monaco Parts surrounding Port Hercules in La Condamine, Monaco The airport peninsula, the industrial area of Cornigliano, the PSA container terminal and other parts of the port in Genoa, Italy The Fens in East Anglia Venice, Italy Rione Orsini, part of Borgo Santa Lucia, Naples A big part of Kavala, city in Greece Fucine Lake, ItalyWaterfront Centre, Jersey The Foreshore in Cape Town The Hassan II Mosque in Morocco is built on reclaimed land.
The Eko Atlantic in Lagos, Nigeria. Large parts of Rio de Janeiro, most notably several blocks in the new docks area, the entire Flamengo Park and the neighborhood of Urca Parts of Florianópolis. Parts of New Orleans Parts of Montevideo, Rambla Sur and several projects still going on in Montevideo's Bay. Much of the urbanized area adjacent to San Francisco Bay, including most of San Francisco's waterfront and Financial District, San Francisco International Airport, the Port of Oakland, large portions of the city of Alameda has been reclaimed from the bay. Mexico City. Parts of Panama City urban and street development are based on reclaimed land, using material extracted from Panama Canal excavations; the Chicago shoreline The Northwestern University Lakefill, part of the campus of Northwestern University in Evanston, Illinois Back Bay, Massachusetts Battery Park City, Ma
Cecil County, Maryland
Cecil County is a county located in the U. S. state of Maryland. As of the 2010 census, the population was 101,108; the county seat is Elkton. The county was named for Cecil Calvert, 2nd Baron Baltimore, the first Proprietary Governor of the Province of Maryland, it is the only Maryland county, part of the Philadelphia-Camden-Wilmington, PA-NJ-DE-MD Metropolitan Statistical Area. Cecil County has existed since the late 1600s, though it continued to grow in population and town size; the area now known as Cecil County was an important trading center long before the county's official organization in 1674 by proclamation of Lord Baltimore. It had been a northeastern part of a much larger Baltimore County, in the northeastern portion of the Province; this had included present-day Baltimore City and county, Carroll, eastern Frederick, portions of Howard and Anne Arundel counties. At the time of its founding, Cecil County included modern Kent County and the border on the Eastern Shore of the Chesapeake Bay went as far south as the Chester River, until its formation in 1706.
The Piscataway traded with the Susquehannocks near Conowingo, with Lenape of the Delaware valley and their Nanticoke allies near the Elk River and Elk Neck Peninsula. A southern tribe sometimes called the Shawnace moved into what became North East, Maryland. Captain John Smith visited the area in 1608. William Claiborne, a Puritan trader based in Virginia, earlier established a trading post at what is now known as Garrett island at the mouth of the Susquehanna River near what became Perryville. Bohemian immigrant Augustine Herman lobbied for Cecil County's creation, drew the 1674 maps, in exchange for which Herman received extensive land grants, including one developed as Bohemia Manor, where he died. Another early developer was George Talbot, appointed Surveyor-General of Maryland in 1683, who came from Ballyconnell, County Cavan, Ireland; until the American Revolution, Cecil County was an important shipping center, both within the colonies and abroad. It exported not only its own agricultural products but animal skins from the west and tobacco from the south.
St. Francis Xavier Church begun as a Jesuit mission in 1704 and rebuilt in 1792, is one of Maryland's oldest churches, though now a museum. St. Mary Anne's Episcopal Church, rebuilt in 1742 is another. West Nottingham Academy founded by Presbyterian Rev. Samuel Finley in 1744, educated Benjamin Rush and Richard Stockton, both of whom signed the Declaration of Independence, still operates today; the Principio Furnace, founded in 1719, became an important exporter of pig iron. During the American Revolution both British and colonial troops traveled through Cecil County, although no major battles occurred within its borders; the Battle of Cooch's Bridge occurred in nearby Delaware, both General Howe and General George Washington stopped in Elkton during the summer of 1777. Robert Alexander, the area's delegate to the Continental Congress of 1776, spoke with both sides but decided to go into exile in England without his wife, she remained a loyal Marylander and received a life estate in some of Elkton property that Maryland confiscated.
The War of 1812 caused Cecil County considerable damage. Not only did British Admiral George Cockburn blockade the upper Chesapeake bay, in response to musket fire from colonials at Welch Point, his troops destroyed a trading post known as Frenchtown, they tried to sail further up the Elk River to the county seat at Elkton, but turned back under fire from Fort Defiance hindered by a cable across the navigation channel. British troops destroyed most of Havre de Grace in nearby Harford County, Maryland. Cockburn's ships traveled up the Sassafras River, meeting resistance, destroyed Georgetown and Fredericktown, Maryland. Avoiding Port Deposit which rumors called defended, the British destroyed the Principio Iron Works, an important military target. Port Deposit boomed after the Susquehanna Canal opened in 1812. Engineer James Rumsey, who grew up in Bohemia Manor before moving to Bath, invented a steamboat which he demonstrated to George Washington, before traveling to London to secure patents against competition from John Finch.
Rumsey died there in 1792, but his lawyer brother Benjamin Rumsey moved south to Joppa and served as Maryland's Chief Justice for 25 years. Steamboats, using technology such as by Robert Fulton, came to dominate travel on the bay during the following decades; the Eagle, built in Philadelphia in 1813, transported travelers between Baltimore and Elkton, where they connected with stagecoaches to travel to Wilmington and other points north. An 1802 attempt to build a canal to connect the Elk River to Christiana, Delaware failed within two years. However, between 1824 and 1829, with financial support from the states of Maryland and Pennsylvania, over 2600 workers built the 14 miles long Chesapeake and Delaware Canal, which became for a while the busiest canal in the new nation; the U. S. Army Corps of Engineers still operates it today, Chesapeake City, Bohemia Manor until 1839, has a museum explaining the canal's importance. Railroads and bridges proved economically important to Cecil County and surrounding region.
The New Castle and Frenchtown Railroad began service in 1831. Railroads crisscrossed Cecil county within three decades, although they greatly reduced its importance as a trading center. Cities such
University of Missouri
The University of Missouri is a public, land-grant research university in Columbia, Missouri. It was founded in 1839 as the first public institution of higher education west of the Mississippi River; the state's largest university, it enrolled 30,870 students in 2017 and offered over 300 degree programs in 21 academic divisions. It is the flagship campus of the University of Missouri System, which has campuses in Kansas City, St. Louis. There are more than 300,000 MU alumni living worldwide with over one half residing in Missouri. In 1908, one of the first schools of journalism was founded by Walter Williams as the Missouri School of Journalism. Forty-five years in 1953, the school began operating the country's only university-owned TV network affiliate, it is one of the 34 public universities that are members of the Association of American Universities. The University of Missouri Research Reactor Center is the world's most powerful university research reactor; the university operates the University of Missouri Health Care system, which operates four hospitals in Mid-Missouri.
The athletics teams are known as the Missouri Tigers. The FBS football team in Missouri is the only FBS program in Missouri and it competes as a member of the Southeastern Conference; the school's mascot, Truman the Tiger, is named after Missourian and former U. S. president Harry S. Truman. MU claims that the university held the first American football homecoming in 1911. In 1839, the Missouri Legislature passed the Geyer Act to establish funds for a state university, it would be the first public university west of the Mississippi River. To secure the university, the citizens of Columbia and Boone County pledged $117,921 in cash and land to beat out five other central Missouri counties for the location of the state university; the land on which the university was constructed was just south of Columbia's downtown and owned by James S. Rollins, he was called the "Father of the University." As the first public university in the Louisiana Purchase, the school was shaped by Thomas Jefferson's ideas about public education.
In 1862 the American Civil War forced the university to close for much of the year. Residents of Columbia formed a Union "home guard" militia that became known as the "Fighting Tigers of Columbia", they were given the name for their readiness to protect the university. In 1890, the university's newly formed football team took the name the "Tigers" after the Civil War militia. In 1870 the institution was granted land-grant college status under the Morrill Act of 1862; the act led to the founding of the Missouri School of Mines and Metallurgy as an offshoot of the main campus in Columbia. It developed as the present-day Missouri University of Technology. In 1888 the Missouri Agricultural Experiment Station opened; this grew to encompass ten centers and research farms around Missouri. By 1890 the university encompassed a normal college, engineering college and science college, school of agriculture and mechanical arts. School of medicine, school of law. On January 9, 1892, Academic Hall, the institution's main building, burned in a fire that gutted the building, leaving little more standing than six stone Ionic columns.
Under the administration of Missouri Governor David R. Francis, the university was rebuilt, with additions that shaped the modern institution. After the fire, some state residents tried to have the university moved further west to Sedalia; the columns were retained as a symbol of the historic campus. Today they are surrounded by the oldest part of campus. At the quad's southern end is Academic Hall's replacement, Jesse Hall, named for Richard Jesse. Built in 1895, Jesse Hall holds Jesse Auditorium; the buildings surrounding the quad were constructed of red brick, leading to this area becoming known as Red Campus. The area was tied together in planned landscaping and walks in 1910 by George Kessler in a City Beautiful design of the grounds. Jesse Hall is scheduled for a $9.8 mil. makeover to include a fire sprinkler system, work on its elevators, a new heating and cooling system as part of a $92 mil. total renovation package the Board of Curators approved in June 2013. This upgrade is expected to be completed in March 2015.
To the east of the quadrangle buildings constructed of white limestone in 1913 and 1914 to accommodate the new academic programs became known as the White Campus. In 1908 the world's first journalism school opened at MU, it became notable for its "Missouri Method" of experience-based instruction. It established an award for "Distinguished Journalism". In April 1923, a black janitor was accused of the rape of the daughter of a University of Missouri professor. James T. Scott was abducted from the Boone County jail by a mob of townsfolk and students, was lynched to death from a bridge near the campus before his trial took place. In the winter of 1935, four graduates of Lincoln University—a traditionally black school about 30 miles away in Jefferson City—were denied admission to MU's graduate school. One of the students, Lloyd L. Gaines, brought his case to the United States Supreme Court. On December 12, 1938, in a landmark 6–2 decision, the court ordered the State of Missouri to admit Gaines to MU's law school or provide a facility of equal stature.
Gaines disappeared in Chicago on March 1939, under suspicious circumstances. The university granted Gaines a posthumous honorary law degree in May 2006. Undergraduate divisions were integrated by court order in 1950, when the university was co
Soil classification deals with the systematic categorization of soils based on distinguishing characteristics as well as criteria that dictate choices in use. Soil classification is a dynamic subject, from the structure of the system itself, to the definitions of classes, in the application in the field. Soil classification can be approached from the perspective of soil as a material and soil as a resource. Engineers geotechnical engineers, classify soils according to their engineering properties as they relate to use for foundation support or building material. Modern engineering classification systems are designed to allow an easy transition from field observations to basic predictions of soil engineering properties and behaviors; the most common engineering classification system for soils in North America is the Unified Soil Classification System. The USCS has three major classification groups: coarse-grained soils; the USCS further subdivides the three major soil classes for clarification.
It distinguishes sands from gravels by grain size, further classifying some as "well-graded" and the rest as "poorly-graded". Silts and clays are distinguished by the soils' Atterberg limits, separates "high-plasticity" from "low-plasticity" soils as well. Moderately organic soils are considered subdivisions of silts and clays, are distinguished from inorganic soils by changes in their plasticity properties on drying; the European soil classification system is similar, differing in coding and in adding an "intermediate-plasticity" classification for silts and clays, in minor details. Other engineering soil classification systems in the United States include the AASHTO Soil Classification System, which classifies soils and aggregates relative to their suitability for pavement construction, the Modified Burmister system, which works to the USCS, but includes more coding for various soil properties. A full geotechnical engineering soil description will include other properties of the soil including color, in-situ moisture content, in-situ strength, somewhat more detail about the material properties of the soil than is provided by the USCS code.
The USCS and additional engineering description is standardized in ASTM D 2487. For soil resources, experience has shown that a natural system approach to classification, i.e. grouping soils by their intrinsic property, behaviour, or genesis, results in classes that can be interpreted for many diverse uses. Differing concepts of pedogenesis, differences in the significance of morphological features to various land uses can affect the classification approach. Despite these differences, in a well-constructed system, classification criteria group similar concepts so that interpretations do not vary widely; this is in contrast to a technical system approach to soil classification, where soils are grouped according to their fitness for a specific use and their edaphic characteristics. Natural system approaches to soil classification, such as the French Soil Reference System are based on presumed soil genesis. Systems have developed, such as USDA soil taxonomy and the World Reference Base for Soil Resources, which use taxonomic criteria involving soil morphology and laboratory tests to inform and refine hierarchical classes.
Another approach is numerical classification called ordination, where soil individuals are grouped by multivariate statistical methods such as cluster analysis. This produces natural groupings without requiring any inference about soil genesis. In soil survey, as practiced in the United States, soil classification means criteria based on soil morphology in addition to characteristics developed during soil formation. Criteria are designed to guide choices in soil management; as indicated, this is a hierarchical system, a hybrid of both natural and objective criteria. USDA soil taxonomy provides the core criteria for differentiating soil map units; this is a substantial revision of the 1938 USDA soil taxonomy, a natural system. The USDA classification was developed by Guy Donald Smith, former director of the U. S. Department of Agriculture's soil survey investigations. Soil taxonomy based soil map units are additionally sorted into classes based on technical classification systems. Land Capability Classes, hydric soil, prime farmland are some examples.
The European Union uses the World Reference Base for Soil Resources the Update 2015 of the third edition 2014. The earlier editions of the WRB were used. According to the first edition of the WRB, the booklet "Soils of the European Union" was published by the former Institute of Environment and Sustainability. In addition to scientific soil classification systems, there are vernacular soil classification systems. Folk taxonomies have been used for millennia, while scientifically based systems are recent developments; the US Occupational Safety and Health Administration requires the classification of soils to protect workers from injury when working in excavations and trenches. OSHA uses 3 soil classifications plus one for rock, based on strength but other factors which affect the stability of cut slopes: Stable Rock: natural solid mineral matter that can be excavated with vertical sides and remain intact while exposed. Type A - cohesive, plastic soils with unconfined compressive strength greater than 1.5 ton per square foot, meeting several other