Use of alternate substrates (acetylene, azide, cyanide) for estimating N(2) fixation confirmed that recombined fractions from different bacteria are functional but restricted in complementarity.

Biochar application can influence soil nitrogen (N) cycle through biological and abiotic processes. However, studies on comprehensive examination of the effects biochar microbially mediated N-cycling processes (N mineralization, nitrification, denitrification, fixation) N fate (i.e., plant uptake, N2O emission, leaching) are warranted. Therefore, aim this study was to examine transformation, mi...

Much of the demand for nitrogen (N) in cereal cropping systems is met by using N fertilisers, but the cost of production is increasing and there are also environmental concerns. This has led to a growing interest in exploring other sources of N such as biological N2 fixation. Non-symbiotic N2 fixation (by free-living bacteria in soils or associated with the rhizosphere) has the potential to mee...

The Bertics et al. manuscript addresses the potential simultaneous occurrence of sulfate reduction and N fixation in anaerobic core horizons from the Baltic Sea. This work adds new data to the observations that sulfate-reducing bacteria fix nitrogen. Overall, the technical approach is sound, the conclusions regarding N fixation sound, and the paper is well written. I believe the work to be time...

Estimates of nonsymbiotic and associative nitrogen fixation indicate that nitrogen fixation occurs at magnitudes that may be of agronomic significance. Long-term N balances for crop production, although difficult to measure, are necessary for estimating the amounts of N2 fixed. Techniques using N directly to measure nitrogen fixation and problems involved in employing these techniques are discu...

1.1 Biological nitrogen fixation and nitrogen nutrition in soybean plants Biological nitrogen fixation is one of the most important processes for ecosystem to access available N for all living organisms. Although N2 consists 78% of atmosphere, but the triple bond between two N atoms is very stable, and only a few group of prokaryotes can fix N2 to ammonia by the enzyme nitrogenase. Annual rate ...

The majority of pulp and paper mills now biotreat their combined effluents using activated sludge. On the assumption that their wood-based effluents have negligible fixed N, and that activated-sludge microorganisms will not fix significant N, these mills routinely spend large amounts adding ammonia or urea to their aeration tanks (bioreactors) to permit normal biomass growth. N(2) fixation in s...

N limitation to primary production and other ecosystem processes is widespread. To understand the causes and distribution of N limitation, we must understand the controls of biological N fixation. The physiology of this process is reasonably well characterized, but our understanding of ecological controls is sparse, except in a few cultivated ecosystems. We review information on the ecological ...

The nitrogen-deficient coastal waters of North Carolina contain suspended bacteria potentially able to fix N(2). Bioassays aimed at identifying environmental factors controlling the development and proliferation of N(2) fixation showed that dissolved organic carbon (as simple sugars and sugar alcohols) and particulate organic carbon (derived from Spartina alterniflora) additions elicited and en...

Cyanobacteria-plant symbioses play an important role in many ecosystems due to the fixation of atmospheric nitrogen (N) by the cyanobacterial symbiont. The ubiquitous feather moss Pleurozium schreberi (Brid.) Mitt. is colonized by cyanobacteria in boreal systems with low N deposition. Here, cyanobacteria fix substantial amounts of N₂ and represent a potential N source. The feather moss appears ...