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.

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.

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.
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.
References in periodicals archive ?
Additionally, she thinks herbivores will accelerate nitrogen cycling in some plots, because in high-nitrogen systems, they stimulate growth of fast-growing plants that can tolerate grazing.
Do ungulates accelerate or decelerate nitrogen cycling? For Ecol Manag, 181:189-204.
The carbon fractions study was published in the Open Journal of Soil Science, and the nitrogen cycling study appeared in Nutrient Cycling in Agroecosystems, both in 2012.
The role of fungi in nitrogen cycling process is displayed by the Arbuscular Mycorrhizae fungi (AMF), which also contribute significantly to N nutrition (N uptake and use efficiency) in soil where N[O.sub.3]-N dominates, by increasing plant nitrate uptake, the percentage of plant N derived from fertilizer, and plant N use efficiency [11-17].
She knew she'd be back--and sure enough, in 2006 she became an undergraduate summer student fellow in geochemist Karen Casciotti's laboratory studying microorganisms involved in nitrogen cycling. Her summer project piqued her interest in nitrogen isotopes, so she returned as a graduate student.
Nitrogen cycling and nitrogen saturation in temperate forest ecosystems.
The commercial bacterial supplement failed to improve the nitrogen cycling capability of the system.
Decomposition and Nitrogen Cycling in Coastal Marine Sediments - Controls by Temperature, Organic Matter Inputs, and Benthic Macrofauna.
3) The abundance of arbuscular mycorrhizal fungi, and consequent interaction with nitrogen cycling prokaryotes, will further alter nitrogen cycling dynamics, and will be associated with lower nitrate leaching
Proteobacteria are critical for carbon and nitrogen cycling in the soil, and the fact that they are more likely to stay close to home during dust storms is good news for soil health, Acosta-Martinez says.--By Dennis O'Brien, ARS.