An experiment in trench composting.

In a previous blog, I wrote about some of the benefits of trench composting. A process in which kitchen scraps are dumped into a shallow trench and covered with dirt to speed up the breakdown process. What I did not gleam from my web sources was just how long it took for the breakdown to occur. I surmised also that factors like the composition of the scraps and the size would come into play. (I figured an egg shell would take quite some time where as cantaloupe rinds might decompose much more quickly. I also felt that scraps that were cut up into small pieces might decompose more quickly).

So, I decided it might be fun to try a simple experiment whereby I would dig a small trench and then divide it in half with a piece of clear glass. After filling in one side, it would give me a viewing window on all the strata of soil from the top down to where the scraps were buried. My initial guess was that the scraps would take about two weeks to completely break down. Now, this was a pretty simple setup to be sure and I wondered about local dogs digging the whole thing up. So, as insurance, I covered the area with a bit of chicken wire.

I began the experiment on Tuesday, July 27, 2010. The weather on this date was hot with the afternoon temperatures in the mid nineties. I took a container of scraps that weighed 1766 grams (about 3 ¾ pounds) and dumped it into a trench area that measured about 12 by 14 and which was 8 inches deep. Now, prior to this I also made sure to cut all the scraps into uniform sizes. Included were the following items, coffee grounds, egg shells, celery, orange peels, old bananas and other assorted odds and ends. (There was no meat present anywhere for this experiment).

Day 1 - As you can see in the picture, the scraps made a tidy little pile about 2 inches deep. Over this was placed about 6 inches of soil that originally came from the hole. The view through the glass was not very good. After getting my pictures, I made sure to cover the open area on the other side of the glass with a small board so it would be dark. Then, I placed a piece of chicken wire over that. Thusly, day one was concluded. I decided to come back to this spot one week from now to uncover and record the degree of decomposition.

Day 2 - I went out to check my little experiment only to find the area had been dug up sometime overnight. Undeterred, I added another batch of scraps (2068 grams) to the bottom of the trench and covered this with soil. I then replaced the board and weighted it down with a heavy pot. I also dispensed with the glass pane at this time. You can't really see anything with this set up. I'll rethink that concept.  So, the experiment continues.

Day 7 - A week has passed but the weather outside is so hot I have put off my inspection for another day or so. Hey it was 103!

Day 8 - I went over to the spot where the scraps were buried and dug down with a trowel. Nope, not broken down. So, I recovered the area and will check in another week.

Day 19 - Wow! I checked the hole and there was nothing except brown dirt and one measly piece of brown eggshell. The weather has been in the nineties most of this time and so the soil is very active. But, this was shocking to me.I also noticed that the soil looked a lot more healthy. Gotta keep this up!