In today's Master Composter class, we began to delve into the science of composting. We did some hands-on (and microscopes on) research to help us gain a better understanding of what's happening in the compost bin and what qualities make for good 'post. By comparing samples of NYC soil (grey, dry, lots of rocks and some twigs, not much of a smell) and finished compost (black, moist, crumbly, earthy aroma), we got an observational sense of how the two differ. The soil, frankly, seemed rather nutritionally haggard, whereas the compost had a Nile-River-delta verdancy to it.

When you examine compost with the naked eye-or better yet, with a microscope-you discover a teeming world of invertebrates. Looking through our batch, produced by vermicomposting, we came across worms and worm cocoons as well as mites and springtails. A magnified mite is quite a sight!

In addition to these visible critters, there are numerous other bacteria, fungi, protozoa, et al that are breaking down the organic matter in the bin. Knowing that your compost heap is a complex ecosystem with an eclectic cast of characters will keep you more at ease when you look through your worm bin or compost pile.

Personally, I was somewhat unsettled when I discovered a bunch of brown mites hanging out in our bin. But the thing to remember is that all of these little rascals are helping to decompose the material that you put into the composting system, and they're helping you to live greener. They can be removed if need be, and unless they wildly proliferate, they present no harm.

On the subjects of decomposition and composition, this session brought up several key definitions. Composting, for instance, can be defined as "controlling or managing the process of decomposition." The word "humus" is another essential term in the CT milieu. This is the term used for finished compost, material that has decomposed as much as is possible and is ready for plants to sup on (not an accompaniment for falafel).

When composting, you have to be conscious of the ratio of carbon and nitrogen, key elements in the cycle of life. The ideal carbon to nitrogen ratio in the system is 30 to 1, which you can get if you add approximately equal amounts of protein-providing nitrogen sources ("greens" like vegetable scraps, grass clippings, eggshells, coffee grinds) and energy-giving carbon sources ("browns" like leaves, newspaper, sawdust, teabags, etc.).

While a 30 to 1 ratio might be optimal, I get the feeling that, like many things, you don't need to be obsessive about this-particularly when it comes to low-temperature composting. Every composter's pile is going to be different, and everyone is going to have their own mishigas about what creates the best compost. It's sort of like making pesto. As MC instructor Karla observed, "We can tell you the basics, but everyone is going to have a different recipe."

Next week: Finding Balance in the Compost Pile