Cycle of nitrogen

[Primarygun]

In nitrogen circle, nitrogen-fixing bacteria convert nitrogen into nitrogen compound but not nitrate and can be absorbed by plant,why?

Isn't plant only able to absorb nitrate ions?

[YT2095]

not at all, Think Ammonia based "foods"

 

the bacteria will have proteins that contain Amines (Ammonia groups), it`s only after much further breakdown does it become Nitrates

[Primarygun]

so ammonia and nitrate ions?

By the way, what's the relationship between plankton and zoophyte?

[chadn]

Plants are capable of taking up both NH4 and NO3. NO3 is the usual form in which plants take up nitrogen because its the most common form found in soils. However, almost every plant takes it up in both forms throughout its life. Which nutrient is taken up more than the other is dependent upon a variety of factors including soil pH, temperature, species of plant, age of plant, etc.

 

NO3 once absorbed must be conveted to NH4 within the plant, so NH4 uptake is more energy efficient, but plants can only tolerate so much NH4 before it becomes toxic. In contrast, much larger amounts of NO3 can be tolerated within the plant so the its a give and take. Almost every study shows that most species benefit the most from a combination of NH4 and NO3 rather than one over the other. There are exceptions, for instance, blueberries cannot tolerate NO3.

 

The amounts of NH4 and NO3 also have huge impacts on the amounts of other nutrients and their uptake by plants.

[YT2095]

hence the use of organic matter (well rotted horse crap) for instance on vegetable gardens, you get a great combo of the NH4, NO3, Carbon, minerals etc....

 

and the rotting process uses the bacteria you mention

 

 

oh yeah, and not ALL plants fix nitrogen from the soil, some (legumes) use special node that will fix nitrogen from the air too

 

 

(a fantastic way to make Green Manure)

[chadn]

oh yeah, and not ALL plants fix nitrogen from the soil, some (legumes) use special node that will fix nitrogen from the air too

 

just to clear things up, plants dont fix nitrogen from the air, only bacteria and some algae species do this. The nodules on legumes are actually the result of an infection by a nitrogen-fixating species of bacteria called rhizobium. I created a thread related to this a while back:http://www.scienceforums.net/forums/showthread.php?t=7303

 

Heres a link on the symbiotic relationship between legumes and rhizobium:

http://www.ls.huji.ac.il/~nurit/pho...association.htm

[Primarygun]

Yes. My book said it is nitrogen-fixing bacteria in the root nodules of legumes.

It feeds on the carbohydrate produced by plant, actually decompose them with nitrogen.

What's the product of this metabolic reaction? Ammonia?

[chadn]

What's the product of this metabolic reaction? Ammonia?

 

NH3 which must then be converted to NH4+ by the plant.

[Primarygun]

What's the general formula of nitrogen compound can be absorbed by plant?

NH4(X)?