nitrogen cycle

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nitrogen cycle

n.
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.

nitrogen cycle

n
(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

ni′trogen cy`cle


n.
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.
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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.

nitrogen cycle

The natural circulation of nitrogen (including nitrogen compounds) from air to consuming organisms (plants, animals and bacteria) and back to air.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.nitrogen cycle - the circulation of nitrogennitrogen 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
References in periodicals archive ?
The project will improve knowledge about nitrogen cycling and availability, soil phosphorus and potassium storage, sources of nutrient supply and responsiveness of crops.
Robertson FA, Myers RJK, Saffigna PG (1997) Nitrogen cycling in brigalow clay soils under pasture and cropping.
At Hopland Research and Extension Center (HREC), researcher Lindsey Hendricks-Franco, a doctoral candidate in integrative biology at UC Berkeley, is investigating the postfire nitrogen cycling roles played by ephemeral herbaceous plants such as whisperingbells (Emmenanthe penduliflora) and Brewer's redmaids (Calandrinia breweri) and by herbivores -- black-tailed deer, rodents and rabbits.
27) At this point, little is known about the patterns of nitrogen cycling in the Lake Erie watershed.
Herbivory can be significant in terrestrial nitrogen cycling (Pastor et al, 1993; Frank and Groffman, 1998; Belovsky and Slade, 2000; Singer and Schoenecker, 2003; Murray et al, 2013).
The book identifies the major new issues in understanding nitrogen cycling as greenhouse gas formation and the use of nitrate fertilizers in agriculture with resulting high nitrate levels in fresh water for human use and in the environment.
Nitrogen cycling is a critical environmental issue because crops need to take up nitrogen to grow, but if too much nitrogen is in the soil it can be released in the air as nitrous oxide or leach into waterways.
The topics include soil architecture and its functional manifestation across scales, thermodynamic limits of the critical zone and their relevance to hydropedology, the hydropedology of the North American coastal temperate rainforest, detecting and modeling subsurface flow networks at the hillslope scale, and coupling biogeochemistry and hydropedology to advance carbon and nitrogen cycling science.
Quantitative analyses of nitrogen cycling genes in soils.
Our findings suggest that plant species richness may be particularly important for maintaining ecosystem functions linked to carbon and nitrogen cycling, which sustain carbon sequestration and soil fertility," said Eldridge.
The thaw-induced shifts that we detected directly support conceptual models of carbon and nitrogen cycling in Arctic soils, in which microbes play a central role in greenhouse gas emissions and destabilisation of stored permafrost carbon.
Temporal and spatial variations in nitrogen cycling in deciduous forest ecosystems along an urban-rural gradient.