Long-term experiment

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.

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 (Jupiter's Great Red Spot) or undesirable (field observations of chimpanzee behavior).

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.

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.

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.

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

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