A hotbed is a biological term for an area of decaying organic matter that is warmer than its surroundings. The heat gradient is generated by the

decomposition Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is e ...

of organic substituents within the pile by microorganism metabolization. A hotbed covered with a small glass cover (also called a hotbox) is used as a small version of a hothouse (heated greenhouse or

cold frame In agriculture and gardening, a cold frame is a transparent-roofed enclosure, built low to the ground, used to protect plants from adverse weather, primarily excessive cold or wet. The transparent top admits sunlight and prevents heat escape via co ...

). Oftentimes, this bed is made of

manure 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 Soil fertility, fertility of soil by adding organic ma ...

from animals such as

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...

s, which pass undigested plant

cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell w ...

in their

droppings Feces ( or faeces), known colloquially and in slang as poo and poop, are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a relati ...

, creating a good environment for microorganisms to come and break down the cellulose and create a hotbed. (The digestive systems of

ruminants Ruminants (suborder Ruminantia) are hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The ...

such as cattle and sheep destroy and use all cellulose in their food, and their droppings remain cold and do not heat up.) Some egg-laying animals, such as the brush turkey, make or use hotbeds to incubate their eggs. By extension, the term ''hotbed'' is used metaphorically to describe an environment that is ideal for the growth or development of something, especially of something undesirable.

References

Biodegradation Composting Ecology Horticultural techniques Horticulture {{Horticulture-stub