I was told that it was not possible to have more nitrite than nitrate in a given soil or plant extract. Is this true? If it is true, can someone please explain or provide some reference(s) to why it is NOT POSSIBLE to have more nitrite than nitrate in a soil or plant sample/extract?
Hi Kauahi, yes it is possible. Nitrification in soil is basically a 2 stage process
The first step of nitrification involves ammonia-oxidizing bacteria oxidizing ammonia to nitrite according to equation (1).
NH3 + O2 → NO2-+ 3H+ + 2e- (1)
Nitrosomonas is the most frequently identified genus associated with this step
The second step of the process involves nitrite-oxidizing bacteria oxidizing nitrite to nitrate according to equation (2).
NO2- + H2O → NO3- + 2H+ +2e- (2)
Nitrobacter is the most frequently identified genus associated with this second step.
If somehting inhibits the second step, but not the forst step (like a change in environmental conditions or a toxin/stress that affects Nitrobacter more acutely), you can get a build up of nitrite.
Yes, it is possible to have more nitrite in a soil sample than nitrate. This can occur when nitrifying bacteria convert ammonium to nitrite more quickly than they convert nitrite to nitrate.
Agreed about the soil. Anhydrous NH3 bands can exhibit this phenomenon. Nitrate is toxic in plants so it's concentration is usually well-controlled.
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