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Nitrogen fixation

About: Nitrogen fixation is a research topic. Over the lifetime, 7940 publications have been published within this topic receiving 232921 citations. The topic is also known as: GO:0009399.


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Journal ArticleDOI
TL;DR: There appears to be a very strong case for improving inoculation methods and for selecting rhizobia not only for effectiveness but also for migration in soil and along the root in a range of conditions.
Abstract: Greenhouse and field experiments were made to investigate the influence of root nodule position on nitrogen fixation in soybean. The N-15 isotope dilution method was used to quantify N 2 fixed. Differences in the location of nodules on roots were induced through varying the inoculation procedure, timing or depth of inoculum placement in the soil. Movement of Bradyrhizobium japonicum in soil and rhizosphere was very limited, and nodule formation was restricted largely to the vicinity within which the bradyrhizobia were placed. With seed inoculation, most of the nodules occurred on the crown of the roots (0–5 cm segment of root), in contrast to the profuse and well distributed nodules when the inoculum was applied throughout the soil. Nodules were mostly on the lower portions of the roots when inoculum was below the seed. Nodule position affected N 2 fixation, with nodules formed on the lower part of the root system fixing significantly more N 2 than the crown nodules, and the later-formed nodules contributed also substantially to the total amount of N 2 fixed by the soybean. There appears to be a very strong case for improving inoculation methods and for selecting rhizobia not only for effectiveness but also for migration in soil and along the root in a range of conditions.

92 citations

Journal ArticleDOI
TL;DR: Based on the N economy of the shoots, it appeared that any N addition to the soil in harvest residues varied with crop and location, and the proportion was reduced when the availability of soil moisture and molybdenum were constrained.

92 citations

Journal ArticleDOI
TL;DR: The estimate of the rate of N fixation is comparable to that of denitrification rates in UK shelf seas, and a diversity of expressed nifH genes, and 21 different prokaryotic n ifH transcripts were identified.
Abstract: In temperate Atlantic waters (18.8 to 20.1°C), biological nitrogen fixation has been demonstrated by 2 independent measurements: 15 N-N2 incorporation and nifH identification in the DNA and expressed messenger RNA (mRNA). At 2 stations in the western English Channel, bulk waters were incubated with 15 N-N2. At the high levels of particulate nitrogen (≤11.5 µmol N l -1 ), absolute fixation rates of 18.9 ± 0.01 and 20.0 nmol N l -1 d -1 were determined. While a caveat must accompany the magnitude of the rates presented due to the limited number of data, the presence and activity of diazotrophic organisms in these waters is of ecological significance and may affect current attitudes to nitrogen and carbon budgets. In particular, our estimate of the rate of N fixation (0.35 mmol N m -2 d -1 ) is comparable to that of denitrification rates in UK shelf seas. Molecular analy- sis identified a diversity of expressed nifH genes, and 21 different prokaryotic nifH transcripts were identified.

92 citations

Journal ArticleDOI
TL;DR: In this article, the response of nitrogen fixation rates resulting from concentrations of P and Fe that actually exist in nodules was studied and it was shown that higher concentrations of these two elements not only stimulated higher nitrogen fixation rate, but were associated with an enhanced ability to export ureides from the nodules.

92 citations

Journal ArticleDOI
TL;DR: Nitrogen fixation by cyanobacteria associated with Sphagnum mosses, influences moss growth by transfer of fixed nitrogen to the moss and shows that factors regulating nitrogen fixation will have a direct effect on the role of SphagnUM dominated ecosystems with respect to carbon cycling.
Abstract: Despite the general assumption that nitrogen fixed by associated cyanobacteria will be readily utilised for growth by the Sphagnum, no empirical evidence is available in the literature. Therefore the effects of nitrogen transfer from cyanobacteria associated with S. riparium were investigated. Cultivation of S. riparium with and without cyanobacteria was performed under laboratory conditions for 57 days. We show that nitrogen fixation by cyanobacteria associated with Sphagnum mosses, influences moss growth by transfer of fixed nitrogen to the moss. More than 35 % of the nitrogen fixed by cyanobacteria was transferred to the newly formed moss biomass and resulted in an increase in the growth of Sphagnum biomass compared to the controls. The variation in the increase of nitrogen content explained 76 % of the biomass increment. Hence, nitrogen fixation will have immediate effect on the carbon fixation by Sphagnum. This shows that factors regulating nitrogen fixation will have a direct effect on the role of Sphagnum dominated ecosystems with respect to carbon cycling.

91 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023390
2022831
2021263
2020240
2019250
2018261