Questions related to Biological Nitrogen Fixation
How we need to consider soil mineral nitrogen availability regarding this?
General perception is that a fast growing species are better carbon sequester if it holds than all CDM projects will have these species. What will be role of old species and other slow or moderate growth species vis a vis role of site quality with respect to fast growing species. How to determine carbon sequestration potential of and species mean ideal parameters for consideration eg. age of tree, site factor / surrounds, tree associates/ allelopathy nature, nutrient cycle / physiology/ silvics of the species etc.
N-fixation by various leguminous and non-leguminous plants is important and its quantification as function of nature of crop, crop growing condition, soil environment, soil N availability and N-addition needs to be evaluated. We wish to know from the experts colleagues on this kind of work done and like to share the publications by the group on this important aspect, as well some of the empirical technical coefficient generators in this regard.
All plants need relatively large amounts of nitrogen (N) for proper growth and development. Biological nitrogen fixation (BNF) is the term used for a process in which nitrogen gas (N2) from the atmosphere is incorporated into the tissue of certain plants. Only a select group of plants (legumes) is able to obtain N this way, with the help of soil microorganisms. What characteristics make legumes fix nitrogen?
I am doing some literature review to better understand the processes governing the biological fixation of nitrogen by non-symbiotic micro-organisms (associative, endophytic, free-living...).
I am not interested in symbiotic relations like legumes (which have their use), but rather to find solutions to promote this fixation throughout the cultivation (perhaps through composting?).
So it could be in the field or in a compost pile on the farm.
Could you share some insights?
Diazotrophs 'fix' atmospheric nitrogen into biologically available forms. In very general, non-technical terms, an over-abundance of these organic nitrogen forms within a soil beyond what biota in the soil metabolically require has been suggested to result in the increase of nitric acid in the soil. What I would be very interested in is if anyone has done work to help establish a rate of nitric acid production in response to this over abundance of organic nitrogen.
I am looking for a way to estimate the root biomass of a grass-clover stock using visual methods, such as counting roots in a defined area of the soil cross-section. The overall objective is to calculate the total amount of nitrogen and thus also the fixation capacity with the aid of the biomass determined in this way. So, which methods are known for this?
I heard that some species of Rhizobia can fix nitrogen even in the absence of plant roots. If someone knows about it, please let me know what conditions are required for Rhizobia to fix atmospheric nitrogen. Thanks
Economic and environmental costs of chemical N in agriculture is becoming a global concern. At the same time climate, change together with food insecurity is the most pressing problem for the 21st century. Indicating the demand for sustainable agricultural practices including the use of legume- rhizobium symbiosis driven biological nitrogen fixation. Is it economically visible if these N-fixing properties of legume also introduced to cereals?
Pulses are known to fix atmospheric nitrogen through bacterial symbiosis. But only a single molecule of fixed nitrogen consumes about 16 molecules of ATP and the carbohydrate provided to the symbionts by the plant is also used up for the growth and development of the symbionts. So it is clear that a copious amount of photosynthates are consumed in the process of nitrogen fixation.
On the other hand, pulses have the roots which can preferentially uptake soil available nitrogen inhibiting the symbiosis. So, there is a possibility that a normal nitrogen fertilization to pulses may inhibit biological fixation and may help to divert more photosynthates to the economic part.
The problem of excessive vegetative growth may be solved by the judicious splitting of the doses or with drip fertigation techniques.
Please share your views on the matter.
Azotobacter is a nonsymbiotic nitrogen fixer used to fix atmospheric nitrogen, so we can save N through chemical fertilisers upto 20-25 %. PSB are added in soil to solubilise P in the soil,. Besides, they secrete Plant Growth Promoting hormones thus both biofertilizers r beneficial for plant growth. Can these biofertilizers also play a role in solubilising silica in the soil, which increases the resistance of plants against diseases?
I am working with Nitrogen fixating organisms especially cyanobacteria and Heterotrophic bacteria. For quantifying nitrogen fixation rates by these micro organisms ARA used. I need to know the about the Gas chromatography condition separate acetylene and ethylene (I am using Elite Capillary Alumina KCL column (0.53*50m)). I am waiting for your valuable comments.
What are the most important environmental factors, including the soil factors most affecting nodule formation or biological nitrogen fixation?
Is nitrogease enzyme (nifH) are stable in extreme environments??
I want to measure biological nitrogen fixation activity in some legumes using acetylene reduction assay. I got an acetylene cylinder with a regulator and just wondering how to take constant gas samples each time? Thank you.
Hi, I'm not biogeochemistry specialist. This isn't my area. So this question may seem stupid to some.
I would like to know if there may be excess biological nitrogen fixation and if this carries some negative impact. If anyone can give me references on this topic, I will be grateful.
I want to know the importance of %nitrogen derived from atmosphere(%Ndfa) in estimating biological nitrogen fixation(BNF).
Some nitrogen fixing endophytic bacteria belong to the genera such as Klebsiella, Enterobacter, Herbaspirillum, Stenotrophomonas, Rhizobium, Bradirhizobium had been detected from plant extracted DNA.Same plant samples were stamped on Nitrogen minus MR agar plate for isolation of the mentioned bacteria. Only Rhizobium and Bradirhizobium was isolated and other not isolated.can I get information of suitable media/technique for isolation of Klebsiella, Enterobacter, Herbaspirillum,Stenotrophomonas please?
There are several methods of measuring nitrogen fixation ability of bacterial cells (like acetylene reduction assay etc) , but is there any protocol or research paper from which we can directly find out nitrogen fixing ability of root nodule.
I am working on N2 production by none denitrifying bacteria. To be sure that N2 produced by these organisms actually is from the N2O route, I need to spike the culture medium with labelled N2O and trace the yield of labelled N2
Hi, I am interested in measuring nitrogenase activity in free living bacteria. Specifically i am interested in measuring through the 15N2 method which measures the organic nitrogen through mas spectometry. Nevertheless, I would l would like to know why it does not take into account other forms of nitrogen in the supernatant or intracellular. For example Labelled amonnia.
Can nitrogen fixation occurs in non legume plants? It is well know that nitrogen fixation occurs in legume plants. But our Q Can nitrogen fixation occurs in non legume plants such as wheat, rice and corn.
I want to determine the effect of elite indigenous rhizobia strains on nitrogen use efficiency
I’m planning to investigate free-living nitrogen-fixing microorganism application as an alternative to chemical fertilization and soil restoration. In the application of nitrogen-fixing microorganisms (diazotrophs) it is very common the use those who are in symbiosis with leguminous plants. But, it is well known that a significant number of plant species that feed humanity (e.g. wheat, corn, rice) do not have the capacity to form this type of symbiosis; Therefore, other ways have been sought to supply for this lack. One of these is the use of microorganisms that make asymbiotic fixation. However, the species until now used, have been studied and obtained in pure microbial cultures, and for various causes low ability to colonize soils for agricultural use has been found, especially those highly degraded.
Recently, alternatives have been developed for the use of microbial communities in mixed cultures or consortia, but so far no relationship with biological nitrogen fixation. So, I’m really looking to find out what you’d consider to be the most limiting factors in the application of this nitrogen fixation consortia to no-leguminous crops.
In the extreme desert, soil nutrients, especially nitrogen are always very poor. Are significant effects observed among local desert plants? I want to know your opinions about which are the key factors controlling nitrogen use efficiency of desert plants in extreme environments?
How nitrogen fixation ability of Azotobacter on solid media? please give exact composition. We tried GNFMM but it produced yellow color rather blue?
I'm having the hardest time finding this information. If anyone knows of a reference leading me to it I'd be most appreciative.
I know rhizobia bacteria fix nitrogen when symbiotic with leguminous plant.But when culture on nitrogen free media that's time can fix atmospheric nitrogen.
By qualitative assay, we have found some bacteria showing positive to utilize nitrogen in Nfb media. Now we are trying to quantify nitrogen fixation by these endophytic bacteria. So if anyone can suggest which method we can apply to quantify nitrogen fixation . How is the Kjeldahl method?
We are growing Azotobacter in liquid medium and can't obtain cysts after fermentation. We tried to use minimal salt medium, tried to mix the obtained liquid with other materials such as butanol, glycerol, liquid humus, starch, gum arabicum, PVP but no formation of cysts we can observe. Furthermore the number of colony forming units are decreasing very faster, i.e. during storage of one month the number of CFU 109 decrease until 108. Maybe someone can suggest some methods how to induce cyst formation of Azotobacter vinelandii in liquid medium and how to keep the number of cells for a long storage?
I am working on biological nitrogen fixation and I wanted to screen the microbes for nitrogen fixation attributes. Is there a method to find nitrogen fixation by microbial isolates apart from Gas chromatography method (ARA).
i need to make primary screening for biological nitrogen fixing endophytes, concerning the amount of fixed nitrogen in liquid media?
I am working of Nitrogen fixation and I wanted to find Nitrogenase activity. I want to know a very good method to find nitrogen fixation method apart from Gas chromatography method.
I want to determine the nitrogen fixation efficiency of some bacterial isolates in my lab. How can i do it with simplest lab settings?
I want to extract growth substances such as gibberellins and Auxins from nitrogen fixing cyanobacteria Anabaena sp..
Dear researcher, I know that nitrogenase is responsible to fix atmospheric nitrogen. Which technique are used to detect the nitrogenase enzyme? Please tell me answer so I will gratitude for everybody.
I'm just wondering whether molybdenum is absolutely necessary to isolate nitrogen fixers using nitrogen-free media. Your replies would be invaluable.
It is possible to apply this method on root nodules and/or on Rhizobia strains (like nitrogen fixation by the free bacteria) and how for each case?
How long Azotobacter will go on multiplying continuously in soil after adding ? What are the factors responsible for their decrease in population in soil ? OR simply adding organic matter in the soil will help to multiply Azotobacter , which was used to treat seeds at the time of sowing ?
I will work on effect of Nitrogen levels on Brachypodium distachyon, and I want know on better of Nitrogen levels can I use it..
I am studying the effects of pH on Biological Nitrogen Fixation and planning to use N15 natural abundance method for determining BNF. Can anyone suggest me if there is any other method more suitable for this particular study?
I am looking for some scholarly articles on the effects of increased soil pH on nitrogen fixation. Can anyone suggest the most read and cited articles on this topic please?
In studies aimed to evaluate the soybean response to nitrogen fertilization in reproductive stages, the rationale for nitrogen application is the assignment or decrease in BNF after flowering. However, I think that if the BNF continues during the reproductive stages, such justification would not make sense.
I appreciate if someone can help me.
In drylands, rhizobial community are in low density. In your opinion, in a experiment to measure the rhizobial population in sites where you expect to be low density, what is the most appropriate serial x-fold dilution to determine the most probably number (MPN)? 10-fold, 5-fold, 2-fold?
While conducting experiments, I experienced that 1000 mg/l ammonium nitrogen was converted to 130 mg/l nitrate nitrogen. This did not make sense to me, although the experiments were conducted in triplicates. Additional experiments also gave similar results
B value represents the fractionation given by the nitrogenase and the 15N distribution in the plant. According to Höwberg (1997), the fractionation during N2-fixation is generally small. Besides, 15N distribution in the plant is not important when we harvest and analyze both above and below ground biomass. I think B value estimation is important when we harvest only above ground biomass, but if it is possible to harvest all biomass, can we assume B=0? What is your opinion about this?
I want information on how to calculate N2 fixation using 15-N based methods for measuring BNF .That is the Principles of the δ15N (15N natural abundance) technique to determine biological N2 fixation (BNF).
With the formula
. %Ndfa = δ15N of reference plant - δ15N of N2-fixing legume x 100
δ15N of reference plant – B 1
), expecally how to calculate for the B vale in the formula
I'm working on nitrogen cycle and I want to quantify the potential rate of nitrification and denitrification through the quantification of functional genes. I want to known how many copies of these genes (nosZ, nirS, nirK and amoA genes) there are in a bacterial genome?
We are interested in getting rhizosphere bacteria with plant growth-promoting activities. We got hundreds of bacterial colonies from environmental samples and we must now evaluate nitrogen fixation in them. Does anyone know selective microbiological methods for these activities?
Suppose I have over-fertilized soil ( festival area - places with the big urine concentration) and I want to accumulate the nitrogen in plants to recycle it further and make it available for other plants. What kind of plant could help me to bind the nitrogen from soil (in similar way as leguminosae fix and accumulate the nitrogen from atmosphere)? Is there any solution to make a use of this natural fertilizer (urine I mean ) which has a peak only two times a year?
Symbiotic N fixation has been shown to respond to N availability and is limited by high energy requirements. Plants appear to use symbiotic N fixation as a facultative strategy to overcome N limitation. However, in many ecosystems, N fixing plants are not present, and even in ecosystem where they are present, N fixation by free-living organisms appears to be an important additional source of N to the ecosystem. But, what controls this input on an ecosystem scale? Is there any observed variation across certain gradients? And how close is the interaction between plants and free-living fixers? Is there plant exudation of labile C as energy provision to free-living heterotrophs? - Thanks for any answers and references!
I am looking for the database about herbs biomass. I need some average data about biomass (C and N) sequestered in entire plant, roots and shoots.
I need it to evaluate "plant biomass" of different sites, according to counted "plant units".
I would like to know if it would be possible to combine both measurements and measure them simultaneously. Are there any studies doing this?
We got results of nitrogen fixation by unicellular cyanobacteria in an eutrophic estuary. In an eutrophic estuary they have enough nutrients available for their metabolism, so they do not have the need for nitrogen fixation. However, even under these circumstance they continue with nitrogen fixation. What is the reason for this?
Nitrogen input and output from a Capsicum annuum- soil system may be important to determine amount of nitrogen got leached from Chile soil system. We know the added amount of nitrogen to system but what about the N in output (Capsicum annuum fruits)?
I tried to isolate about 150 Endophytic bacteria from the roots and nodules of the legume White Lupin. However, I can't identify them due to the lack of PCR or any other apparatus required for molecular identification in our laboratory.
Conventional microscopic identification of nitrogen fixing cyanobacteria and heterotrophic bacteria (growing in nitrogen-free medium) is a difficult task. Does anyone work with a diversity of nitrogen fixing cyanobacteria and heterotrophic bacteria?
There are some concerns about the use of 15N enrichment and 15N natural abundance to quantify the contribution of biological nitrogen fixation.
Molecular tools allow us to measure the diversity and also abundance of some functional genes, such as nitrogen fixation genes(nif H), ammonia oxidation genes (amo B) etc. For the gene diversity and gene abundance, which one has more contribution to the biogeochemical processes and to the ecosystem?