A Rhizotron is a laboratory constructed underground in order to study the soil

Soil

Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

 and its interactions with plants and animals. Typically equipped with a central corridor with viewing windows into the soil profiles on either side. On the outside , separate bays are constructed to enable specific experiment

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...

s to be carried out by varying the soil composition and the plant and animals contained therein.

Rhizotrons are in use at Kew Gardens

Royal Botanic Gardens, Kew

The Royal Botanic Gardens, Kew, usually referred to as Kew Gardens, is 121 hectares of gardens and botanical glasshouses between Richmond and Kew in southwest London, England. "The Royal Botanic Gardens, Kew" and the brand name "Kew" are also used as umbrella terms for the institution that runs...

 . at the USDA

United States Department of Agriculture

The United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...

 Northern Research Station at Houghton

Houghton, Michigan

Houghton is a city in the U.S. state of Michigan's Upper Peninsula and largest city in the Copper Country on the Keweenaw Peninsula. As of the 2010 census, the city population was 7,708. It is the county seat of Houghton County...

, and at Treborth Botanic Garden

Treborth Botanic Garden

Treborth Botanic Garden , is a botanic garden in Wales, close to the city of Bangor, Gwynedd. It is owned by Bangor University, and is used in teaching for University students, local schools and community groups...

, near Bangor

Bangor, Gwynedd

Bangor is a city in Gwynedd, north west Wales, and one of the smallest cities in Britain. It is a university city with a population of 13,725 at the 2001 census, not including around 10,000 students at Bangor University. Including nearby Menai Bridge on Anglesey, which does not however form part of...