Dear
ceg
thank you for your detailed reply
but I can't understand last paragraph
do you mean that
replacing the source of N to be NH4/NH3 instead of NO3 will be good for both red and green ?
Hi Mohamed,
Nitrogen uptake and assimilation are tricky. On one hand, the N that is bound in NH3/NH4 is very easy for plants to use and is more abundant per unit weight. For example, NH4 by weight is mostly N since the Hydrogen (H) is the lightest element. In NH4 78% of that weight is N, so in 1 gram of NH4 there is 0.78 gram of N.
In NO3 only 22% of that weight is N, so 1 gram of NO3 yields only 0.22 gram of N.
Furthermore, the energy required to convert, for example NH4, to the chemical amine (-NH2) is very small. It's then very easy to produce amino acids which are used to build proteins.
Producing the same result using NO3 is a more elaborate procedure separating the 3 Oxygen atoms from N. This requires extra enzymes and extra steps so the energy required to use N in this case is less efficient.
On the other hand, there is a downside. Whereas NO3 is non-toxic and can be stored in huge quantities within the plant tissue, NH4 is more toxic and NH3 is extremely toxic. Storage within the plant tissues therefore requires elaborate procedures using internal methods of chelation, greatly reducing the efficiency of NH3/NH4.
As a result of this toxicity, NH3/NH4 uptake is carefully regulated and if both NH3/NH4 and NO3 are present in the water column the plant will selectively uptake NO3 when the concentration level of NH3/NH4 in the water column is high.
Most commercial fertilizers therefore use a combination of NH3/NH4 and NO3.
It would NOT be a good idea to unilaterally substitute NH3/NH4 for NO3, but instead to add only small amounts to the NO3.
In a tank with animals I am fundamentally opposed to the use of NH3/NH4 due to this toxicity issue.
In a plants only tanks there is less of a concern and yes, you can get better performance, better growth, darker greens etc. by adding small amounts of NH3/NH4, however, careless application can also trigger algal blooms.
In the tank animal and plant waste break down into NH3/NH4 already and we can add as much NO3 as we want without any worries whatsoever, but we cannot do the same with NH3/NH4.
Hope this clarifies.
Cheers,