nitrogen cycle

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ni·tro·gen cy·cle

the series of events in which the nitrogen of the atmosphere is fixed, thus made available for plant and animal life, and is then returned to the atmosphere: nitrifying bacteria convert N2 and O2 to NO2- and NO3-, the latter being absorbed by plants and converted to protein; if plants decay, the nitrogen is in part given up to the atmosphere and the remainder is converted by microorganisms to ammonia, nitrites, and nitrates; if the plants are eaten, the animals' excreta or bacterial decay return the nitrogen to the soil and air.
Farlex Partner Medical Dictionary © Farlex 2012

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.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

ni·tro·gen cy·cle

(nī'trŏ-jĕn sī'kĕl)
The series of events in which the nitrogen of the atmosphere is fixed, thus made available for plant and animal life, and is then returned to the atmosphere: nitrifying bacteria convert N2 and O2 to NO2- and NO3-, the latter being absorbed by plants and converted to protein; if plants decay, the nitrogen is in part given up to the atmosphere and the remainder is converted by microorganisms to ammonia, nitrites, and nitrates; if the plants are eaten, the animals' excreta or bacterial decay return the nitrogen to the soil and air.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
Nitrogen cycleclick for a larger image
Fig. 229 Nitrogen cycle .

nitrogen cycle

the circulation of nitrogen in the environment as a result of the activity of living organisms. 80% of the atmosphere is made up of nitrogen and this is maintained by the balancing action of the cycle.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
The values obtained for nitrogen-fixing bacteria that use malate as a carbon source were similar for all three municipalities, with an average count of 3.0 x [10.sup.4] CFU/g dry soil.
It has been shown that inoculating seeds with N-Fix before planting leads to successful colonization of nitrogen-fixing bacteria in each of the crops treated [23].
It eliminated human dependence on nitrogen-fixing bacteria and freed societies from an ecological limit that all previous societies were subject to.
Changes in acetylene reduction activities and effects of inoculated rhizosphere nitrogen-fixing bacteria on rice.
16S ribossomal DNA characterization of nitrogen-fixing bacteria isolated from banana (Musa spp.) and pineapple (Ananas comosus (L) Merril).
But the vast farms where leaf-cutter ants raise fungal crops may harbor a crew of previously overlooked farmhands: nitrogen-fixing bacteria.
of Dundee and Scottish Crop Institute, UK) summarizes current knowledge on the world's leguminous plants and their symbiotic nitrogen-fixing bacteria and provides details on aspects that have not been covered in depth in other volumes.
Summary: TEHRAN (FNA)- Findings of a new study showed that the ant farmers, which cultivate fungus for food, like their human counterparts, depend on nitrogen-fixing bacteria to make their gardens grow.
Nitrogen-fixing bacteria from representative soil series of the Lower Rio Grande Valley region of southern Texas were examined for their symbiotic association with common 'Pinto' been (Phaseolus vulgaris L.).
Think of the nitrogen-fixing bacteria without which we would probably not survive.
The roots of peas and beans are particularly good for composting, as they contain nitrogen-fixing bacteria which help raise the level of nitrogen in the soil for crops the following year.