Long-term experiment

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A long-term experiment is an experimental procedure that runs through a long period of time, in order to test a hypothesis or observe a phenomenon that takes place at an extremely slow rate. What duration is considered "long" depends on the academic discipline. For example, several agricultural field experiments have run for more than 100 years, but much shorter experiments may qualify as "long-term" in other disciplines. An experiment 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 (e.g. Jupiter's Great Red Spot) or undesirable (e.g. field observations of chimpanzee behavior).

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In physics

The Oxford Electric Bell has been ringing at Oxford University since 1840, although there is some reason to believe it may be 15 years older. [1]

The Beverly Clock at the University of Otago has been running since 1864.

The pitch drop experiment has been running at the University of Queensland since 1927.

In botany

The William James Beal Germination Experiment has been running since 1879. It is the oldest on-going experiment in botany. It is scheduled for completion in 2100.

The Godwin Plots experiment at the Wicken Fen reserve in Cambridgeshire, England, has been running since the 1920s and explores the differences between areas of vegetation which are never cut, and respectively all four, three or two years and every year.

In agricultural research

Broadbalk Experiment Rothamsted Broadbalk Experiment Rothamstead.jpg
Broadbalk Experiment Rothamsted

Long-term experiments test the sustainability of different farming practices, as measured by yield trends over decades. Examples include the Park Grass Experiment at Rothamsted Experimental Station (1843–present), the Morrow Plots (1876–present) at the University of Illinois at Urbana–Champaign, Sanborn Field at the University of Missouri (1888-present), the Magruder Plots (1892–present) at Oklahoma State University, Auburn's Old Rotation (1896–present), and the Haughley Experiment (1939–1982?).

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". [2] These results show that practices considered unsustainable by some advocates of sustainable agriculture may preserve "the ability of a farm to produce perpetually", at least under some circumstances. But even if crop diversity in space or time (crop rotation) and organic inputs are not always essential to sustainability, there is abundant evidence from Rothamsted and elsewhere that they are often beneficial.

An experiment in alpine pasture has been ongoing in Switzerland at Schynige Platte from the 1920s looking at the human effect on the alpine environment. [3]

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. [4]

Various short-term experiments have used legumes (in symbiosis with nitrogen-fixing rhizobia) 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 nitrogen removed in a harvested crop over the long term. A key point is that the nitrogen 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 nitrogen 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. [5]

In microbiology and evolutionary biology

In microbiology

A photo showing the components of the 500-year microbiology experiment 500 Year Microbiology Experiment2.JPG
A photo showing the components of the 500-year microbiology experiment
Chroococcidiopsis glass ampoules Chrococcidiopsis Glass Ampoules.jpg
Chroococcidiopsis glass ampoules

At the UK Centre for Astrobiology within The University of Edinburgh and at the Institute of Aerospace Medicine with the German Aerospace Centre, Charles Cockell and Ralf Möller established the "500-Year Microbiology Experiment" that started in July 2014 to study the loss of viability of desiccation-resistant bacteria over long periods. The experiment involves the study of vegetative bacteria (the extreme tolerant cyanobacterium, Chroococcidiopsis sp.) and spore-forming bacteria (Bacillus subtilis). [6] [7]

The experiment comprises two oak wooden boxes containing duplicate samples, to be kept at the University of Edinburgh and the Natural History Museum. Every two years for the next 24 years, and thereafter every 25 years for the next 475 years, triplicate samples of both organisms contained within glass ampoules will be opened and the number of viable cells enumerated. The first time point was taken in 2014, and the last is intended to be taken on 30 June 2514. Within each box, the experiment is duplicated into a reduced and non-reduced background radiation experiment, with one set of samples being kept in a lead box to cut back background radiation, allowing the impact of radiation in combination with desiccation on viability to be studied over long periods. It was motivated by a desire to understand how microbes survive desiccation in deserts, rocks, permafrost and their potential survival in space. The destruction and pathways of degradation of biomolecules will also be studied. In addition to the core experiment, there are a variety of samples including dried agar plates and endoliths for investigation over long periods.

One of the wooden boxes was delivered to the Natural History Museum on 27 February 2015, and will be curated within the cyanobacterial collection.

In evolutionary biology

The E. coli long-term evolution experiment (LTEE), a study in experimental evolution initated by Richard Lenski, has been underway since 1988 for more than 70,000 generations. [8] [9] Experiments with the evolution of maize under artificial selection for oil and protein content represent more years, but far fewer generations (only 65). [10] [11]

The domesticated silver fox, an ongoing breeding program since 1959 with dramatic results.

The "Dark Fly" experiment started by Syuichi Mori (Kyoto University) in 1954 studies evolution of common fruit fly reared in a constant dark room for 57 years (over 1400 generations). In 2012, the third successor of the experiment, Naoyuki Fuse, performed the full genome sequencing of the strain, and reported around 5% alterations from the wildlife strain. [12]

In ecology

The US National Science Foundation supports a number of long-term ecological experiments, mostly in ecosystems that are less directly affected by humans than most agricultural ecosystems are. See LTER. Within the UK the Ecological Continuity Trust works to promote and secure the future of long-term ecological experiments, maintaining a register of experiments where treatments have been applied for a minimum of six years.

A number of other areas, sometimes called involuntary parks, can be regarded as long time ecological experiments, because they have been abandoned by humans and returned to near-feral condition. These include areas abandoned for political reasons, such as the Korean Demilitarized Zone, or environmental contamination, such as the Chernobyl Nuclear Power Plant Exclusion Zone.

In medicine and psychology

The Framingham Heart Study has been running continuously since 1948.

The Grant Study at the Laboratory of Adult Development in the Department of Psychiatry at Brigham and Women's Hospital, a Harvard Medical School affiliate, is conducting a longitudinal study of human adult development, by following two groups of individuals as they age (268 Harvard graduates and 456 males from inner-city Boston). The study has been ongoing since 1937 and is currently the longest running study of adult life ever conducted.

Related Research Articles

<span class="mw-page-title-main">Guar</span> Species of flowering plant in the bean family Fabaceae

The guar or cluster bean, with the botanical name Cyamopsis tetragonoloba, is an annual legume and the source of guar gum. It is also known as gavar, gawar, or guvar bean.

<span class="mw-page-title-main">Crop rotation</span> Agricultural practice of changing crops

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

<span class="mw-page-title-main">Organic farming</span> Method of agriculture meant to be environmentally friendly

Organic farming, also known as ecological farming or biological farming, is an agricultural system that uses fertilizers of organic origin such as compost manure, green manure, and bone meal and places emphasis on techniques such as crop rotation and companion planting. It originated early in the 20th century in reaction to rapidly changing farming practices. Certified organic agriculture accounts for 70 million hectares globally, with over half of that total in Australia. Organic farming continues to be developed by various organizations today. Biological pest control, mixed cropping, and the fostering of insect predators are encouraged. Organic standards are designed to allow the use of naturally-occurring substances while prohibiting or strictly limiting synthetic substances. For instance, naturally-occurring pesticides such as pyrethrin are permitted, while synthetic fertilizers and pesticides are generally prohibited. Synthetic substances that are allowed include, for example, copper sulfate, elemental sulfur, and ivermectin. Genetically modified organisms, nanomaterials, human sewage sludge, plant growth regulators, hormones, and antibiotic use in livestock husbandry are prohibited. Organic farming advocates claim advantages in sustainability, openness, self-sufficiency, autonomy and independence, health, food security, and food safety.

<span class="mw-page-title-main">Rothamsted Research</span> UK agricultural research institution

Rothamsted Research, previously known as the Rothamsted Experimental Station and then the Institute of Arable Crops Research, is one of the oldest agricultural research institutions in the world, having been founded in 1843. It is located at Harpenden in the English county of Hertfordshire and is a registered charity under English law.

<span class="mw-page-title-main">Sustainable agriculture</span> Farming approach that balances environmental, economic and social factors in the long term

Sustainable agriculture is farming in sustainable ways meeting society's present food and textile needs, without compromising the ability for current or future generations to meet their needs. It can be based on an understanding of ecosystem services. There are many methods to increase the sustainability of agriculture. When developing agriculture within sustainable food systems, it is important to develop flexible business process and farming practices. Agriculture has an enormous environmental footprint, playing a significant role in causing climate change, water scarcity, water pollution, land degradation, deforestation and other processes; it is simultaneously causing environmental changes and being impacted by these changes. Sustainable agriculture consists of environment friendly methods of farming that allow the production of crops or livestock without damage to human or natural systems. It involves preventing adverse effects to soil, water, biodiversity, surrounding or downstream resources—as well as to those working or living on the farm or in neighboring areas. Elements of sustainable agriculture can include permaculture, agroforestry, mixed farming, multiple cropping, and crop rotation.

<span class="mw-page-title-main">Rotational grazing</span> System of grazing moving animals between paddocks around the year

In agriculture, rotational grazing, as opposed to continuous grazing, describes many systems of pasturing, whereby livestock are moved to portions of the pasture, called paddocks, while the other portions rest. Each paddock must provide all the needs of the livestock, such as food, water and sometimes shade and shelter. The approach often produces lower outputs than more intensive animal farming operations, but requires lower inputs, and therefore sometimes produces higher net farm income per animal.

<span class="mw-page-title-main">Rhizobia</span> Nitrogen fixing soil bacteria

Rhizobia are diazotrophic bacteria that fix nitrogen after becoming established inside the root nodules of legumes (Fabaceae). To express genes for nitrogen fixation, rhizobia require a plant host; they cannot independently fix nitrogen. In general, they are gram negative, motile, non-sporulating rods.

<span class="mw-page-title-main">Legume</span> Plant in the family Fabaceae

A legume is a plant in the family Fabaceae, or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock forage and silage, and as soil-enhancing green manure. Well-known legumes include beans, soybeans, chickpeas, peanuts, lentils, lupins, mesquite, carob, tamarind, alfalfa, and clover. Legumes produce a botanically unique type of fruit – a simple dry fruit that develops from a simple carpel and usually dehisces on two sides.

<span class="mw-page-title-main">Green manure</span> Organic material left on an agricultural field to be used as a mulch or soil amendment

In agriculture, a green manure is a crop specifically cultivated to be incorporated into the soil while still green. Typically, the green manure's biomass is incorporated with a plow or disk, as is often done with (brown) manure. The primary goal is to add organic matter to the soil for its benefits. Green manuring is often used with legume crops to add nitrogen to the soil for following crops, especially in organic farming, but is also used in conventional farming.

<span class="mw-page-title-main">Cover crop</span> Crop planted to manage erosion and soil quality

In agriculture, cover crops are plants that are planted to cover the soil rather than for the purpose of being harvested. Cover crops manage soil erosion, soil fertility, soil quality, water, weeds, pests, diseases, biodiversity and wildlife in an agroecosystem—an ecological system managed and shaped by humans. Cover crops may be an off-season crop planted after harvesting the cash crop. Cover crops are nurse crops in that they increase the survival of the main crop being harvested, and are often grown over winter. In the United States, cover cropping may cost as much as $35 per acre.

<span class="mw-page-title-main">Polyculture</span> Growing multiple crops together in agriculture

In agriculture, polyculture is the practice of growing more than one crop species in the same space, at the same time. In doing this, polyculture attempts to mimic the diversity of natural ecosystems. Polyculture is the opposite of monoculture, in which only one plant or animal species is cultivated together. Polyculture can improve control of some pests, weeds, and diseases while reducing the need for pesticides. Intercrops of legumes with non-legumes can increase yields on low-nitrogen soils due to biological nitrogen fixation. However, polyculture can reduce crop yields due to competition between the mixed species for light, water, or nutrients. It complicates management as species have different growth rates, days to maturity, and harvest requirements: monoculture is more amenable to mechanisation. For these reasons, many farmers in large-scale agriculture continue to rely on monoculture and use crop rotation to add diversity to the system.

<span class="mw-page-title-main">Nutrient management</span> Management of nutrients in agriculture

Nutrient management is the science and practice directed to link soil, crop, weather, and hydrologic factors with cultural, irrigation, and soil and water conservation practices to achieve optimal nutrient use efficiency, crop yields, crop quality, and economic returns, while reducing off-site transport of nutrients (fertilizer) that may impact the environment. It involves matching a specific field soil, climate, and crop management conditions to rate, source, timing, and place of nutrient application.

<span class="mw-page-title-main">Jean-Baptiste Boussingault</span> French chemist (1801–1887)

Jean-Baptiste Joseph Dieudonné Boussingault was a French chemist who made significant contributions to agricultural science, petroleum science and metallurgy.

<span class="mw-page-title-main">Organic fertilizer</span> Fertilizer developed from natural processes

Organic fertilizers are fertilizers that are naturally produced. Fertilizers are materials that can be added to soil or plants, in order to provide nutrients and sustain growth. Typical organic fertilizers include all animal waste including meat processing waste, manure, slurry, and guano; plus plant based fertilizers such as compost; and biosolids. Inorganic "organic fertilizers" include minerals and ash. The organic-mess refers to the Principles of Organic Agriculture, which determines whether a fertilizer can be used for commercial organic agriculture, not whether the fertilizer consists of organic compounds.

The effect of organic farming has been a subject of interest for researchers. Theory suggests that organic farming practices, which exclude the use of most synthetic pesticides and fertilizers, may be beneficial for biodiversity. This is generally shown to be true for soils scaled to the area of cultivated land, where species abundance is, on average, 30% richer than that of conventional farms. However, for crop yield-scaled land the effect of organic farming on biodiversity is highly debated due to the significantly lower yields compared to conventional farms.

<span class="mw-page-title-main">The Rodale Institute</span>

Rodale Institute is a non-profit organization that supports research into organic farming. It was founded in Emmaus, Pennsylvania in 1947 by J. I. Rodale, an organic living entrepreneur. After J.I. Rodale died in 1971, his son Robert Rodale purchased 333 acres and moved the farm to Kutztown, Pennsylvania.

<span class="mw-page-title-main">Agricultural pollution</span> Type of pollution caused by agriculture

Agricultural pollution refers to biotic and abiotic byproducts of farming practices that result in contamination or degradation of the environment and surrounding ecosystems, and/or cause injury to humans and their economic interests. The pollution may come from a variety of sources, ranging from point source water pollution to more diffuse, landscape-level causes, also known as non-point source pollution and air pollution. Once in the environment these pollutants can have both direct effects in surrounding ecosystems, i.e. killing local wildlife or contaminating drinking water, and downstream effects such as dead zones caused by agricultural runoff is concentrated in large water bodies.

<span class="mw-page-title-main">Biofertilizer</span> Substance with micro-organisms

A biofertilizer is a substance which contains living micro-organisms which, when applied to seeds, plant surfaces, or soil, colonize the rhizosphere or the interior of the plant and promotes growth by increasing the supply or availability of primary nutrients to the host plant. Biofertilizers add nutrients through the natural processes of nitrogen fixation, solubilizing phosphorus, and stimulating plant growth through the synthesis of growth-promoting substances. The micro-organisms in biofertilizers restore the soil's natural nutrient cycle and build soil organic matter. Through the use of biofertilizers, healthy plants can be grown, while enhancing the sustainability and the health of the soil. Biofertilizers can be expected to reduce the use of synthetic fertilizers and pesticides, but they are not yet able to replace their use. Since they play several roles, a preferred scientific term for such beneficial bacteria is "plant-growth promoting rhizobacteria" (PGPR).

<span class="mw-page-title-main">History of fertilizer</span>

The history of fertilizer has largely shaped political, economic, and social circumstances in their traditional uses. Subsequently, there has been a radical reshaping of environmental conditions following the development of chemically synthesized fertilizers.

<span class="mw-page-title-main">Manure</span> Organic matter, mostly derived from animal feces, which can be used as fertilizer

Manure is organic matter that is used as organic fertilizer in agriculture. Most manure consists of animal feces; other sources include compost and green manure. Manures contribute to the fertility of soil by adding organic matter and nutrients, such as nitrogen, that are utilised by bacteria, fungi and other organisms in the soil. Higher organisms then feed on the fungi and bacteria in a chain of life that comprises the soil food web.

References

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