Long-term experiment
A long-term experiment
An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...

 is an experimental procedure that runs through a long period of time, in order to test a hypothesis
A hypothesis is a proposed explanation for a phenomenon. The term derives from the Greek, ὑποτιθέναι – hypotithenai meaning "to put under" or "to suppose". For a hypothesis to be put forward as a scientific hypothesis, the scientific method requires that one can test it...

 or observe a phenomenon that takes place at an extremely slow rate.

Several agricultural field experiment
Field experiment
A field experiment applies the scientific method to experimentally examine an intervention in the real world rather than in the laboratory...

s have run for more than 100 years, but much shorter experiments may qualify as "long-term" in other disciplines. An experiment
An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...

 is "a set of actions and observations", implying that one or more treatments (fertilizer, subsidized school lunches, etc.) is imposed on the system under study. Long-term experiments therefore contrast with nonexperimental long-term studies in which manipulation of the system studied is impossible (Jupiter's Great Red Spot) or undesirable (field observations of chimpanzee
Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...



Visible sunspot measurements have been made since the 18th century.

The Oxford Electric Bell
Oxford Electric Bell
The Oxford Electric Bell or Clarendon Dry Pile is an experimental electric bell that was set up in 1840 and which has rung almost continuously ever since. It is located in the foyer of the Clarendon Laboratory at the University of Oxford, England...

 has been ringing at Oxford University since 1840, although there is some reason to believe it may be 15 years older.

The Beverly Clock
Beverly Clock
The Beverly Clock is a clock situated in the foyer of the Department of Physics at the University of Otago, Dunedin, New Zealand. The clock is still running despite never having been manually wound since its construction in 1864 by Arthur Beverly....

 at the University of Otago
University of Otago
The University of Otago in Dunedin is New Zealand's oldest university with over 22,000 students enrolled during 2010.The university has New Zealand's highest average research quality and in New Zealand is second only to the University of Auckland in the number of A rated academic researchers it...

 has been running since 1864.

The pitch drop experiment
Pitch drop experiment
The pitch drop experiment is a long-term experiment which measures the flow of a piece of pitch over many years. Pitch is the name for any of a number of highly viscous liquids which appear solid, most commonly bitumen...

 has been running at the University of Queensland
University of Queensland
The University of Queensland, also known as UQ, is a public university located in state of Queensland, Australia. Founded in 1909, it is the oldest and largest university in Queensland and the fifth oldest in the nation...

 since 1927.

Arthur Covington
Arthur Covington
Arthur Edwin Covington is a Canadian physicist who made the first radio astronomy measurements in Canada...

's microwave solar observatory has been running since 1947, currently at the Dominion Astrophysical Observatory
Dominion Astrophysical Observatory
The Dominion Astrophysical Observatory, located on Observatory Hill, in Saanich, British Columbia, was completed in 1918 by the Canadian government. Proposed and designed by John S...


Long-term agricultural field experiments

Long-term experiments test the sustainability of different farming practices, as measured by yield trends over decades. Examples include the Rothamsted Experimental Station
Rothamsted Experimental Station
The Rothamsted Experimental Station, one of the oldest agricultural research institutions in the world, is located at Harpenden in Hertfordshire, England. It is now known as Rothamsted Research...

 (1843–present), the Morrow Plots
Morrow Plots
The Morrow Plots is an experimental corn field at the University of Illinois at Urbana-Champaign and is the oldest of its kind in the Western hemisphere and the second oldest in the world. It was established in 1876 as the first experimental corn field at an American college and continues to be...

 (1876–present), Alabama's Old Rotation
Old Rotation
The Old Rotation is a soil fertility experiment on the Auburn University campus in Auburn, Alabama. The Old Rotation experiment, which started in 1896, is the third-oldest ongoing field crop experiment in the United States and the oldest continuous cotton experiment in the world...

 (1896–present), and the Haughley Experiment
Haughley Experiment
The Haughley Experiment was the first scientific comparative study of organic farming and conventional chemical-based farming, started in 1939 by Lady Eve Balfour and Alice Debenham, on two adjoining farms in Haughley Green, Suffolk, England....


Experiments at Rothamsted showed that "grain yields can be sustained (and even increased) for almost 150 years in monocultures of wheat and barley given organic or inorganic fertilizer annually". These results show that practices considered unsustainable by some advocates of sustainable agriculture
Sustainable agriculture
Sustainable agriculture is the practice of farming using principles of ecology, the study of relationships between organisms and their environment...

 may preserve "the ability of a farm to produce perpetually", at least under some circumstances. But even if crop diversity
Crop diversity
Crop diversity is the variance in genetic and phenotypic characteristics of plants used in agriculture. Crops may vary in seed size, branching pattern, in height, flower color, fruiting time, or flavor. They may also vary in less obvious characteristics such as their response to heat, cold or...

 in space or time (crop rotation
Crop rotation
Crop rotation is the practice of growing a series of dissimilar types of crops in the same area in sequential seasons.Crop rotation confers various benefits to the soil. A traditional element of crop rotation is the replenishment of nitrogen through the use of green manure in sequence with cereals...

) and organic inputs are not always essential to sustainability, there is abundant evidence from Rothamsted and elsewhere that they are often beneficial.

The Haughley Experiment was noteworthy as a rare example of a long-term experiment in organic farming without external inputs of nutrients. After about 30 years, however, it was decided to start importing manure. There is some disagreement whether a "decline in relative yields from the organic section" was due to a depletion of soil nutrients.

Various short-term experiments have used legumes (in symbiosis with nitrogen-fixing rhizobia
Rhizobia are soil bacteria that fix nitrogen after becoming established inside root nodules of legumes . Rhizobia require a plant host; they cannot independently fix nitrogen...

) as a nitrogen source, but good short-term yields do not prove the system is sustainable. The problem is that release of nitrogen from soil organic matter can make up any shortfall of nitrogen from legumes for a decade or more. The Old Rotation showed that nitrogen from legumes can balance N removed in a harvested crop over the long term. A key point is that the N in the legumes was not removed, as it would be with a soybean crop, but was plowed under as a green manure. In the Old Rotation, the green manure was grown during the winter to supply N to a summer crop (cotton); this would be less practical in colder climates.

Long-term agricultural experiments that have been started more recently include the Long-Term Research on Agricultural Systems experiments at UC Davis, started in 1993.

Long-term ecological experiments

The US National Science Foundation supports a number of long-term ecological experiments, mostly in ecosystems that are less directly impacted by humans than most agricultural ecosystems are. See LTER.

A number of other areas, sometimes called involuntary park
Involuntary park
Involuntary park is a neologism coined by science fiction author and environmentalist Bruce Sterling to describe previously inhabited areas that for environmental, economic or political reasons have, in Sterling's words, "lost their value for technological instrumentalism" and been allowed to...

s, can be regarded as long time ecological experiments, because they have been abandoned by humans and returned to near-feral
A feral organism is one that has changed from being domesticated to being wild or untamed. In the case of plants it is a movement from cultivated to uncultivated or controlled to volunteer. The introduction of feral animals or plants to their non-native regions, like any introduced species, may...

 condition. These include areas abandoned for political reasons, such as the Korean Demilitarized Zone
Korean Demilitarized Zone
The Korean Demilitarized Zone is a strip of land running across the Korean Peninsula that serves as a buffer zone between North and South Korea. The DMZ cuts the Korean Peninsula roughly in half, crossing the 38th parallel on an angle, with the west end of the DMZ lying south of the parallel and...

, or environmental contamination, such as the Chernobyl Nuclear Power Plant Exclusion Zone.

Long-term experiments in evolutionary biology

The experiments of Richard Lenski
Richard Lenski
Richard E. Lenski is an American evolutionary biologist. He is the son of sociologist Gerhard Lenski. He earned his BA from Oberlin College in 1976, and his PhD from the University of North Carolina in 1982...

 on evolution of E. coli
E. coli long-term evolution experiment
The E. coli long-term evolution experiment is an ongoing study in experimental evolution led by Richard Lenski that has been tracking genetic changes in 12 initially identical populations of asexual Escherichia coli bacteria since 24 February 1988...

 have been underway for more than 20,000 generations. Experiments with the evolution of maize under artificial selection for oil and protein content represent more years but far fewer generations (only 65).


The Laboratory of Adult Development in the Department of Psychiatry at Brigham and Women's Hospital
Brigham and Women's Hospital
Brigham and Women's Hospital is the largest hospital of the Longwood Medical and Academic Area in Boston, Massachusetts. It is directly adjacent to Harvard Medical School of which it is the second largest teaching affiliate with 793 beds...

, a Harvard Medical School
Harvard Medical School
Harvard Medical School is the graduate medical school of Harvard University. It is located in the Longwood Medical Area of the Mission Hill neighborhood of Boston, Massachusetts....

 affiliate, is conducting a longitudinal study
Longitudinal study
A longitudinal study is a correlational research study that involves repeated observations of the same variables over long periods of time — often many decades. It is a type of observational study. Longitudinal studies are often used in psychology to study developmental trends across the...

 of human adult development
Adult development
Adult Development is a branch of developmental psychology that deals specifically with how adults age through physical, emotional, and cognitive means...

, by following two groups of individuals (268 Harvard
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...

 graduates and 456 males from inner-city Boston
Boston is the capital of and largest city in Massachusetts, and is one of the oldest cities in the United States. The largest city in New England, Boston is regarded as the unofficial "Capital of New England" for its economic and cultural impact on the entire New England region. The city proper had...

) as they age. The study has been ongoing for 68 years and is currently the longest running study of adult life ever conducted.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.