In March 2023 I got a tumbling compost bin with dual chambers similar to the one I had in Houston.

It took a few weeks to fill one of the chambers with compostable waste, and I also included several handfuls of store-bought compost. Then I left that chamber to “cook” while I filled the other side. Both chambers were tumbled several times a week, and moistened when it rained.
My prior experience with a dual chamber tumbling composter was that by the time one side became full, the other side was ready to harvest and use as compost. It was chunkier than store-bought compost, often with recognizable components (e.g., peach stones), but it was moist and presumably filled with decayed organic material that the soil would appreciate.
Not so with my first load here, which I have emptied out underneath the composter. Really it just looks dried out and not decayed. The only part that remotely looks soil-like I suspect is the bagged compost that I put in originally.

I can still end up using this somewhere here, as ugly mulch if nothing else. Obviously I’d prefer to have a process that makes something that more resembles compost, so what might have gone wrong here? Here are some possibilities with comments.
- Not enough “greens”? Compost is made from “browns” which are dry or woody items such as fallen leaves and twigs, and “greens” which are items that have been recently growing such as fruit and vegetable scraps. Both browns and greens are important because they provide different nutrients. I would estimate that we add more greens than browns, so I don’t think this is the problem.
- Not hot enough? Some of the decay organisms that work on compost need heat. However, we have had one of the hottest summers on record with about three months of daily temperatures above 100F, so I rather doubt that is the problem here.
- Not wet enough? This is definitely a possibility since we have had (and are still in) an extended drought, and it wasn’t until recently that I even thought to water the compost. I will start to do that more.
- Not enough decay organisms to start the process? With a dual chamber composter, when harvesting, normally I leave some of the prior load in the chamber to inoculate the next batch. Or if you are beginning the process, you can include some of your current soil from the garden to get it started. I knew the soil here would be useless because it’s so sterile, which is why I added compost from a bag. However, that might not have been a good source of organisms either, so I will use a compost starter to hopefully kick-start the process.
So the first load of compost didn’t really work as I’d hoped. But it can sit under the composter for now and eventually it may break down further with time and as compost juices drip onto it from above. In the meantime I will work on the second batch with the use of a compost starter and paying more attention to moisture.

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