Do plants contribute to the nitrogen cycle?

[lance]

Do plants help to break down the NH3/NH4 n' the nitrites?

just wondering if they contribute to the nitrogen cycle or do they merely absorb the nitrates?

[loupgarou]

plants take nh4 and no2 more readily than no3.

[vinz]

Plants prefer ammonia or ammonium (I can't remember which) before nitrate. I think they don't take nitrites or at least it's the least prefered.

[vinz]

Chris, you sure about NO2? I better go look it up again.

[bclee]

Plants merely absorb the NH3. They do not take part in converting NH3 to NO2. They for they do not aid in the nitrogen cycle. They do not absorb NO2.

Now talking about cycling the planted tank. Since plants are readily absorb NH3, that also means you may not see a NH3 spike which in turn you don't see the NO2 spike. But the bacteria colony should be developing despite of the absence of the spikes. Therefore, if you are able to get the plants to grow well or at least settle well in the tank in the begining, you may not have to wait for the cycling to be over before introducing the fishes.

BC

[bclee]

BTW, NH3 and NH4+ exist together in the water. The ratio of one to the other depends on the pH of the water.

NH3(aq) + H2O <---> NH4+ + OH-

BC

[lance]

Thanks BCLee

now i understand why i stopped seeing the spikes after i have introduced the plants. I was expecting to see more ammonia spikes n' was wondering if my tank was already cycled.

[Allen_1971]

according to diana walstad, there has not been a conclusive study on the uptake of nitrites by plants... however there was a study done using duckweed, and in it it showed that duckweed took up nitrites and ammonia more readily than nitrates with no preference for either of the former.

So the best assumption we can make is that all plants readily take in ammonia, some plants take in NO2 as easily as ammonia, and most plants prefer NO3 least... (haha ok maybe its not the best assumption)

[vinz]

BC,

How does the pH affect the ratio of NH3 to NH4?

[loupgarou]

http://www.bio-elite.com/nitrogen_faq.htm

[Allen_1971]

Vinz,

heres a more detailed look at the effects of ph/temp on NH3/NH4 from the krib

http://www.thekrib.com/Chemistry/ammonia-toxicity.html

Allen