nitrogen cycle

The circulation of nitrogen in nature, consisting of a cycle of chemical reactions in which nitrogen from the atmosphere is fixed in compounds in soil or water, assimilated by plants and animals, released to the soil and water through decomposition, and returned to the atmosphere through denitrification.

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

nitrogen cycle

(Biology) the natural circulation of nitrogen by living organisms. Nitrates in the soil, derived from dead organic matter by bacterial action, are absorbed and synthesized into complex organic compounds by plants and reduced to nitrates again when the plants and the animals feeding on them die and decay. See nitrification, nitrogen fixation

Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

ni′trogen cy`cle

the continuous sequence of natural processes by which nitrogen in the atmosphere and nitrogenous compounds in the soil are converted, as by nitrification and nitrogen fixation, into substances that can be utilized by green plants and then returned to the air and soil as a result of denitrification and plant decay.

nitrogen cycle

nitrogen cycle

The continuous process by which nitrogen is exchanged between organisms and the environment. Some of the atmosphere's free nitrogen combines with other elements to form compounds that are deposited in the soil. These are then converted by bacteria, in a process called nitrification, into nutrients that are absorbed by the roots of green plants. Nitrogen is then passed into the food chain and returned to the soil by the metabolism and decay of plants and animals.

The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

nitrogen cycle

The natural circulation of nitrogen (including nitrogen compounds) from air to consuming organisms (plants, animals and bacteria) and back to air.

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Noun

nitrogen cycle - the circulation of nitrogen; nitrates from the soil are absorbed by plants which are eaten by animals that die and decay returning the nitrogen back to the soil

biological process, organic process - a process occurring in living organisms

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References in periodicals archive

et al 2003 Human health effects of a changing global nitrogen cycle The Ecological Society of America 1: 240-246.

Metabolismos microbianos involucrados en procesos avanzados para la remocion de Nitrogeno, una revision prospectiva

"Our trials so far suggest there are no major issues, although biochar may have the potential to lock in nitrogen, so slowing the nitrogen cycle and affecting crop growth, which we need to assess."

Welsh farmers tap Amazon fertiliser; 'Biochar' offers climate solution

In the future, however, with rising populations and demands for food and energy, human-made sources of nitrogen are projected to double natural inputs to the environment, reported two of the world's leading nitrogen cycle experts, Nicolas Gruber of the Swiss Federal Institute of Technology and James N.

Chemical detectives follow nitrogen's elusive and essential trail in the ocean: the 'isotope effect' offers a new way to track nitrogen

"The role legumes can play in reducing excess nitrogen in the nitrogen cycle is not widely recognized," says Russelle, who is in the ARS Plant Science Research Unit at St.

Keeping nitrogen out of waterways: legume crops may help farmers manage manure

Arboreal emissions of nitrogen oxides are "evidently an important component of the nitrogen cycle," Hari says.

Scotch pines emit nitrogen oxides into the air. (Fallen Trees?)

The nitrogen cycle converts ammonia to nitrate, which is only toxic to fish in large amounts.

Aquaponics: the marriage of fish farming and hydroponics. (2003 Feature Section--"Themes and Extremes")

* discuss nitrogen nutrition and the nitrogen cycle

Chapter 12: Plant nutrition

The roles of the legume in the nitrogen cycle of productive and sustainable pastures.

Sweetclover: a Potential Problem for the Northern Great Plains

Henderson GS, Harris WF (1975) An ecosystem approach to characterisation of the nitrogen cycle in a deciduous forest watershed.

Mineralisation of nitrogen in a chronosequence of rehabilitated bauxite mines

2-3 on the nitrogen cycle is taken, without correction, from authors who did not understand the cycle or the chemistry involved.

Principles of Ecology in Plant Production

More importantly, synthetically derived fertilizers contain high salt levels and other compounds (perhaps even pesticides), which are harmful to worms and microorganisms; they may impair the nitrogen-fixing ability of the bacteria and short-circuit the nitrogen cycle. If you feel that you must add nitrogen, perhaps to a pile made up of only carbon-rich leaves, always try to use organic sources first: spent grounds from a coffee shop, a neighbor's grass clippings, agricultural manures, or dried blood.

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