June 25, 2004

SIUC Country Column: 'Dr. Compost' de-mystifies process of getting started

by K.C. Jaehnig

At our house, the new compost bin -- a big, black, hulking, helmet-shaped thing -- goes by the name Darth Vader. We've been bringing him regular offerings of coffee grounds and gutter gunk since he came home with us on Earth Day, but you know how it is with alien life forms -- you're never really sure they're happy.

When we began reading how to estimate the carbon-nitrogen ratio of a mixture of grass clippings to leaves (C:N = (20 + 50)/2=35), we considered falling on our own light saber. We went into column writing as a career because we weren't good with math. We never dreamed we'd need ratios to dispose of our yard and kitchen waste. Clearly, it was time to seek the in-person wisdom of Dr. Compost, otherwise known as Alan Walters, the man behind the home gardening class offered by Southern Illinois University Carbondale's College of Agricultural Sciences.In our quest to learn how we might appease him, we first sought guidance in the sacred halls of the World Wide Web. There we found that the Way of the Composter was hard, with strict rules: Start with six inches of this, add three inches of that, follow up with two inches of the other and toss in an additional four inches of something else, wetting and stirring all the while. Then there was the dandy little fertilizer formula.

Dr. Compost gave us a funny look when we started talking ratios.

"Just throw in what you have," he said.


"Sprinkle in a handful if you want," he said.

What about layering and turning and keeping it moist as a wrung-out sponge? (And how wet is a wrung-out sponge anyway?) Not to worry, he assured us.

"It makes pretty good compost even if you just let it sit there," he said.

For those of you who like your learning Power Point style, that's pretty much it. Composting isn't hard. Just about anything will turn into compost if you let it sit there long enough.

"Except motor oil -- you never want to add that to your compost pile," he said.

Ha, ha! Dr. Compost does love his little joke!

But most folks don't want to wait three or four years for the lazy man's composting process to run its course. That's where the wetting and the turning and the fertilizer come in. Air, moisture and nitrogen -- a key ingredient in fertilizer -- speed up the breakdown of stuff in a compost bin by making life more pleasant for the microbes that do the work.

"If any of these is lacking, the decomposition process is going to be much slower," Walters said.

Once daytime temperatures consistently reach the 70s, turn or mix the compost ingredients once every couple of weeks or so, he said. Keep everything moist but not so wet that squeezing a handful makes water run out of it.

"That would hinder aeration and slow down decomposition -- and wet piles tend to stink," he said.

As for nitrogen, most of the stuff we'd been feeding to Vader contains it, but not all Vader fodder is created equal. Our vegetable scraps have as much as four times more nitrogen than our leaves do. Our coffee grounds, surprisingly, pack the same nitrogen punch as cow manure does (and at our house are more plentiful).

Speaking of manure, composting guides always suggest the addition of "well-rotted" manure. Since most of the manure we drive past on our way to work each morning looks pretty fresh, we asked Walters where we would get the "well-rotted" stuff.

"From the middle of the pile," he said, without missing a beat.

HA, HA! Dr. Compost was having some fun with us!

Should we choose not to entertain our local farmers in our search for "well-rotted" manure, we could buy it in bags from a garden center or hardware store, he said. Just don't use pet "manure," he cautioned. Dog and cat feces contain nasty microbes that we wouldn't want anywhere near our garden.

Fertilizer would let us avoid the manure question altogether. Walters advised using one labeled 10-10-10, sprinkling a handful into Vader's maw, wetting it and mixing it in.

Walters also recommended giving Vader a little regular soil or even some pre-packaged compost to get things rolling -- "You have to get the microbes in there to begin with," he said -- and shredding the really large or hard stuff (citrus rinds, leaves, twigs, nutshells and such) to make it break down faster.

If it's warm out, and if we have made sure that Vader is full of a moist mix of itty-bitty pieces of scraps and lawn leftovers laced with fertilizer or "well-rotted" manure, and if we have stirred his innards every other week or so, we could have honest-to-gosh compost in just a few months.

But then what? We grow perennials, not vegetables or annuals, so we can hardly work our finished compost into the soil before planting. In our case, Walters advised applying it directly to the soil around the plants right up to the stems, following up with a layer of mulch. As the compost continues to break down, it will work its way into the soil.

"That's what it is -- it's a soil-building mechanism," Walters said. "It breaks the soil up so that plant roots can penetrate the soil faster, and it increases the soil's nutrient- and moisture-holding capacity. Under drought conditions, plants will do much better with a layer of compost around them.

"But it's not a substitute for fertilizer because the microbes use its nitrogen as part of the decomposition process. And while it has some of the attributes of mulch, other materials will do a better job of that than compost."

When the growing season ends, we can feed Vader all the leftovers from this year's garden (including the contents of our hanging baskets and deck planters, potting soil and all), as long as they are free of disease. And once cool weather sets in for good, we can still offer him buckets of kitchen waste. We just don't have to bother with turning or watering it because nothing much will happen inside that dark Maw until it warms up next spring.

So there you have it: Compost 101 in a (shredded, well-rotted) nutshell. And may The (Compost) Fork be with you!