## hpr3408 :: Composting

 Introduction
Welcome to another episode of Hacker Public Radio. This episode is inspired by HPR episode 3157 entitled Compost by Klaatu. During the early 2000's, I lived in a single family home which had a number of oak trees around it. Between the trees, other foliage, and grass, there was a large amount of yard waste. While my city (Baltimore, MD in the US) will pick up your yard waste if you put it in bags by the curb [1], I would use the oak leaves as mulch, and did have a mulch pile of leaves and other yard waste. At that time, I thought about composting food waste, but there is a big issue with rats in Baltimore, and I didn't look into ways to compost. I just knew I couldn't randomly mix it into my mulch pile.
I am currently living in a different house, without any oak trees, and not as much yard waste (particularly since we hire someone to mow the grass every couple weeks). After listening to the Compost episode, I was inspired to look into the best way to do it given my current living situation. The first thing I did was to look and see if there are any laws against composting in Baltimore City. The rat problem is big enough that the City purchased and distributed a large green plastic trash bin to every physical mailing address in the city. This is the bin you are required to use when putting out your trash. Given the situation, I wasn't sure it would be legal to do composting in your back yard. Much to my surprise, it is not only legal, but the city website has a web page on how to compost [2] and just recently started a pilot program for food scrap drop off with seven locations around the city [3].
Kitchen Compost Bin
After determining I wasn't going to be a scofflaw, I went to the Internet to see what kind of bins are available for purchase. While Klaatu gives great suggestions for low cost composting bins, I wanted something that would look nice sitting out on a shelf for the small inside bin. I found the Utopia Kitchen Compost Bin [4]. The bin is made of stainless steel and has a volume of 1.3 gallons (4.9 liters). The lid is rounded and has a series of holes around the top. The inside of the lid holds a circular shaped charcoal filter. The combination of holes and charcoal filter capture any odors generated by the food scraps. It works amazingly well and even with onion scraps you need to stick your nose to the holes and inhale deep to smell anything when the lid is closed. It holds three to seven days worth of food scraps, most of which end up being coffee grinds. We have had this bin for 10 months, and the charcoal filter is still effective. There are replacement filters available for this bin, but you could also cut other charcoal filters to fit inside the lid.
Outside Compost Bin
Given the potential rat and other small critter issues, I wanted the main, outside composter to be fully enclosed, and preferably not sitting directly on the ground. A quick search brings up a number of options, both composters that sit on the ground and ones that are tumbler style, which hang on a frame. I went with a tumbler style compost bin. This provided the desired feature of not being on the ground, and has the added advantage of making it easy to turn the compost every second or third day by just rotating the bin slowly for three or four full turns. I purchased the FCMP Outdoor IM4000 Tumbling Composter [5]. The composter is octagonal shaped column with two chambers inside it. This allows you to fill one chamber while the other side is finishing the composting process. There are also aeration holes for each chamber which can be open to different levels to moderate the amount of moisture. The combined volume of the two chambers is approximately 37 gallons (140 liters).
My Composting Experience
So far I have been very happy with this combination. I just emptied a chamber for the third time. I do have a bit of an issue with the compost being overly damp. I have mixed some drier yard waste in from time to time and that does help, but have had times when parts of it get a little slimy. I have also run into issues with flies and other bugs living in the chamber for a while, but generally I don't see them outside of the composter, just when I open the door to add more material. Not ideal, but not so bad that I did anything about it. I have also found certain things do take extra time to compost, and usually need some manual help to break down. Pits of mangoes and avocados in particular along with corn cobs take a long time to break down. They do start to compost, and are easy to crumble in your hands, but keep their basic shape for a long while. Egg shells don't really break down, as Klaatu mentioned, but they do become very brittle and I crumble them up manually along with the pits and corn cobs. Another issue I have found with damper compost, particularly in cooler months, it doesn't heat up enough to decompose the seeds of some plants. This ended up being a pleasant surprise this summer after mixing in the first batch of compost in our little herb garden during the spring. We now have a combination of plumb and medium sized tomato plants and some kind of squash plant growing in it. If you don't want random plants growing in your yard or flower beds, do be careful when composting plants with seeds [6].
Conclusion
While it takes a little extra effort, composting does reduce the amount of garbage you are sending to the dump, and does reduce the smell of your kitchen trash bin. It also gives a rewarding feeling as you watch the material break down into a rich dirt, and then mix it into your garden or yard. I recommend giving it a try, and posting your experience as another episode of Hacker Public Radio.
References

Baltimore City Department of Public Works-Yard Waste
Baltimore City Department of Public Works-Source Reduction
Baltimore City Department of Public Works-Food Scrap Drop-Off Pilot Program
Utopia Kitchen Compost Bin
FCMP Outdoor IM4000 Tumbling Composter
Composting Tomato Plants: When To Compost Tomatoes

