Tuesday, August 10, 2010

Coffee and Compost, II

When I started thinking about making more compost, my main concern was the turning. When I first started composting I used to move my whole pile every other Saturday, in order to incorporate air. Fresh air helps keep the aerobic bacteria in the pile digesting the materials, and prevents smelly anaerobic bacteria from building up. If the pile is large enough, the body heat from the bacteria warms it up.

My pile that first year was extremely well managed, going through a very hot phase at the beginning and gradually moving on to the wormy, buggy stage that ideally precedes use. The hot phase helps to kill bacteria and weed seeds - commercial/city compost operations use a thermometer to monitor the heat and make sure it gets hot enough for long enough to kill pathogens. (They have peoples' pet poop in their compost, after all.) It is also just lots of fun to watch steam pouring out of the pile when you turn it in December.

Since R was born, I am no longer the composting wonder woman of old. Above you can see my current compost batch, which is crawling with worms and bugs - that's great, but it indicates that the pile isn't very warm. The weed seeds will just have to live on, I decided, and I've been turning my pile about 6 times a year, just enough to keep the tree roots from moving in and the plants that grow in it from going to seed. The result is that the pile finishes more slowly, and not as completely as it did before. Stuff near the edge is more likely to end up back in the pile after I screen than it was before.

The trouble is, I want to make more compost in the same amount of time in the same compost bin, which means I need it to finish faster. So how does a lazy composter like me get more finished compost without much more work? Well, here is my idea:

I took some scraps of PVC pipe from an old project, cut into lengths a few feet long, and drilled three sets of holes going down the length, about 2-3 inches apart. There are five pieces, and my plan is to set them down into the compost bin and fill in compost around them, so that the tops just stick out of the pile. This is something that I've had in mind to do since I built the pile, but it seemed to work so well without them that I never got around to it.

I'm not sure exactly about the length or the number of holes, I just tried to squint at it and ask myself if I thought fresh oxygen was going to get all the way down into the tube, and into the pile, on a regular basis. Hopefully I am not too far off.


  1. Sounds like a reasonable idea. Let us know how it works out.

  2. Naturally! A good scientist must PUBLISH the results of her experiments, right?