-
Second attempt
12/19/2017 at 13:54 • 0 commentsFor my second attempt I decided to measure the initial contents of the bottle more precisely. The diagram below shows how the bottle was put together.
I dried the soil so that I could accurately control how much water the bottle contained at the outset. I didn’t want to overdo the water, partly because the CO2 sensor does not work if the humidity is too high (i.e. if there is condensation), and partly because I want to work out what the minimum water requirement is. It looks as though I haven’t used enough water, since the lower part of the soil still looks dry. I also suspect that the process of drying the soil and funnelling it into the bottle has resulted in soil that is too compacted and won’t allow gases to permeate it. Rather than stop the experiment and add more water, I want to continue it as-is just to see what happens. I used 5 carrot seeds, thinking that not all of them will germinate. They will be overcrowded if they grow large enough. I covered the seeds with a thin layer of damp soil from the garden - the reason for this was that I wanted to make sure that soil microbes were present in the bottle. Drying the soil may have killed the microbes it contained.
I decided to add some moss to the bottle for two reasons. Firstly to see whether it survives. Secondly because I wondered whether there was an overproduction of CO2 in my first attempt. Perhaps the moss will help to maintain an equilibrium in the bottle and consume excess CO2. Until I’ve measured CO2 levels, this is just speculation.
I started this bottle on 8th December, below is a photograph of it.
I noticed yesterday (18th December) that some of the carrot seeds have germinated. I can tell that they are carrot seedlings and not weeds because they still have the carrot seed case attached, as you can see in the photo below.
UPDATE 4th Jan 2018:
The seedlings in this experiment have gone droopy and they look like they will die. This can been seen by comparing this photo from 29th December, when the seedlings were still upright:
With this photo taken today (4th January):
As per my log entry from 2nd January, I believe that there is more CO2 in the bottle than the seedlings can tolerate (although I haven’t measured the CO2 level in this bottle).
-
First attempt
12/19/2017 at 12:44 • 0 commentsMy first (rather informal) attempt at germinating carrot seeds in bottles failed. I placed a few small stones at the bottom of each bottle, put a layer of activated charcoal on top, then put damp soil on top until each bottle was about half full. I put a single carrot seed in each bottle, covered over with some soil. I left the bottles in a reasonably well lit windowsill. The carrot seeds didn’t germinate. I noticed that a few weed seeds that had been in the soil did germinate, and produced rather spindly seedlings which died off after a few days. Now, six weeks later, there is nothing green growing in either bottle. What happened, and why did all of the weeds die? I’m not sure. One possibility is that because there is nothing to recycle the CO2 produced by the soil, it accumulates. Perhaps this makes the water in the bottle acidic. I can test this by measuring the pH of the water and comparing it to a sample of soil from the same place that I took the soil to fill the bottle. I could also try to quickly attach a CO2 meter to the top of one of the bottles without letting too much air escape to see what it reports.