Last week when I tested the compost tea, There was a quite high reading of nitrite and nitrate. The interesting thing is, Even if I gradually increase how much compost I add for the tea, i didnt see it increasing progressively. One thing was quite different though: we had a guest at home, so i got to brewing the tea only on Sunday late in the evening, and let it brew only for about 2 hours. So it got me thinking: what if, there is some nitrate at detectable level in the compost, but that it is used in some way by the living organisms during the brewing process ?
Yesterday, I set my compost tea to brew, with a timer on the side for 1h, 2h and then the next morning (about 12h from the set up time). I also "sacrificed" a strip to measure the water - molasses mixture before adding the compost to get a baseline. Here are the results:
| Time | GH | KH | Ph | NO2- | NO3- |
| 0 | 30 | 80 | 6 | 0 | 0 |
| 1 | 180 | 120 | 7.5 | 10 | 200 |
| 2 | 180 | 120 | 7.5 | 10 | 200 |
| 12 | 180 | 120 | 7.5 | 0 | 0 |
So where does this nitrogen go ?
If nitrates are consumed by denitrification, my pH should increase to some extend. Denitrification is the biological process in which bacteria and fungus are transforming N03- into N2. This process consumes H+ ions [http://www.umich.edu/~lehnert/denitrification.html], which should raise the pH. Most hobby website would mention that denitrification is an anaerobic process, but in fact, some organisms can function in both aerobic and anaerobic modes [http://link.springer.com/article/10.1007%2FBF00408378], but is less efficient in aerobic environment. The pH seems stable, so I would want to say that this is not happening, but possibly the amount of change would not be reflected in the strips measurements. I cant test that without an actual lab. Also I have aeration going in the tea, which should slow down the process if occuring.
My hope Is that bacterial activity is fixing nitrogen into their proteins, which would keep the nitrogen in the system. Some bacteria are able to use N03- as a nitrogen source for their protein synthesis [http://www.bashanfoundation.org/cyli/cylisporocarps.pdf].
Conclusions for me at this point : I will brew my compost teat only for an hour or so from now on. Also, I will not add systematically molasses as there will not be a focus on increasing bacterial life.
