Brown and green to gold: Classic composting

Posted by talkdirt

Posted: May 5, 2008 - 5:51 pm

compost2: Finished compost should look and smell like rich forest loam. Photo by Anchorage Daily News photographer Bob Hallinen.View May Calendar
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Cheryl writes: Two pretty good rules of thumb: Anytime something’s wrong with your soil, add compost.

And anytime something’s wrong with your compost, get out there with a pitchfork and turn it.

At bottom, composting is nothing more than good housekeeping, says Jeff Smeenk, the soil expert at the University of Alaska’s Cooperative Extension Service office in Anchorage. “You take something out and use it, you put it back where it came from,” in the case of compost, back in the good Earth, he told a gathering of gardeners in early spring.

There are lots of good reasons to compost your vegetative-based refuse: If you recycle, you can cut your garbage going to the landfill to almost nothing; finished compost you’ve made for free improves your soil and plant health; it’s a self-sustaining process; and it’s not hard.

Or you can forget the bottom line and go for the magic. It’s pure alchemy, isn’t it? Turning rubbish to garden gold.

You’ll need two things from the garden supply store: A long-stemmed thermometer (not the one you use on hams or roasts, please) to keep track of the heat inside the pile, and a sturdy pitchfork.

You’ll also want a stock of green and brown fixings, water, air and a place to pile your compost as it cooks. The green will be readily available very soon, and right now is a fine time to scavenge the brown as people clean up and bag leaves missed in the fall. Your pile can be in either sun or shade, but downwind from the neighbors, in case it sours, would be kind.

Smeenk uses the image of an Earth-toned layer cake: green / brown / green / brown / green / brown, with an occasional sprinkling of fish meal, cottonseed meal, bone meal, blood meal or the like between layers as a treat for the bacteria, fungi, actinomycetes, protozoa and rotifers toiling away on your behalf.

“Brown” is for carbon. “Green” is for nitrogen. You’re aiming for an approximate mix of 30 parts carbon to 1 part nitrogen, or 30:1, though there’s flex either way.

“Green” includes grass clippings such as weeds (seeds and all), vegetable and fruit peels, and fresh horse, cow or chicken manure. Use only manure from herbivores because dog or cat excrement, or that from other carnivores, carries nasty pathogens for people. Moose poop isn’t especially helpful because it’s so dense and woody.

No meat or fish scraps, or grease. No bones. No eggs. (You don’t want bears, or other troublesome scavengers.) No oil or any petroleum-based product (poison to plants). No vehicles. (A “compost” pile at a home I bought years ago hid a dead Dodge pickup.)

“Brown” includes dry grass clippings and dry hay or straw, shredded newspapers (though not the glossy ad slicks or inserts), egg shells, coffee grounds, tea leaves, and chopped twigs and branches.

The bigger the chunks you toss in, the longer they will take to break down and help you.

The Extension Service has a fine instructional video with Ellen Vande Visse directing the building of a compost pile out in the Mat-Su, sort of a Compost 101.

A good compost pile starts out as at least a 3-foot layered cube. Smaller, and the heat escapes too quickly from the core to break down the content.

Like most things, Smeenk says, you can spend as much as you want on your compost arrangement. What he presented was the classic three-bin set-up for making compost, with the youngest compost in the first bin and the mature, cured compost in the final one. The bins can be built from wood pallets, posts and wire, old hay bales, etc., or you can order more artistic (and far pricier) ones on line.

Or you can dispense with bins altogether and go to piles. If you lay down a sheet of plywood first the pile will be easier to work and turn because the pitchfork won’t be jamming into the ground.

It will help to have your separate stockpiles of brown and green ready and waiting for your pitchfork, like having everything measured out and ready to go before you launch into a recipe. Start with a coarse layer of “brown” between 4-6 inches deep, something like straw or hay or chopped-up branches. Spread it out to 4x4 or 5x5 feet and sprinkle it down with the hose. Then add 4-6 inches of “green” like grass clippings, then another layer of brown, then another layer of green, then a light layer of soil, sprinkling with water to keep it damp, and so on. Stop when it’s about 3 feet tall and spread a plastic tarp over it. This is to keep the rain out, and the moisture you’ve added in.

In the dark, warm damp, which also will have necessary air spaces if you’ve used materials of different sizes, moderate-temperature microorganisms will get right to work. They’ll do their breakdown thing for a couple of days, heating the pile to about 104 degrees Fahrenheit (it’s fun to keep up with this with the thermometer) and preparing the way for the high-temperature microorganisms.

They’ll take over from there and kick the temperatures up to between 131 and 149 degrees for days to months, depending on the composition of the pile, its size, and outside temperatures. That’s what you’re after. But temperatures over 149 degrees will also bake helpful microbes and slow down the decomposition, so if your pile has a hot flash, cool it by turning it with your pitchfork.

After this, the pile will cool naturally and the moderate-temperature microorganisms will return in force to “cure” the compost. Start to finish, this usually takes 6-8 weeks.

Your part in this is to make sure the aerobic bacteria consistently have the oxygen and water and nutrients they need to produce the heat you need to destroy weed seeds and pathogens and end up with good compost. If the pile starts to stink like raw sewage, you don’t have enough oxygen in it and the anerobic bacteria, the oxygen-haters, have taken over. Get out there and turn it. Your good microorganisms are suffocating.

In fact, after 10-12 days, get out there anyway and turn it. The easiest way is to lay down another sheet of plywood and pitchfork the first pile onto it. Check to see if the moisture level is right. When compost is cooking, it should feel like a wrung-out sponge. If you squeeze it and water trickles out, it’s way too wet. Turn it so it can dry some. If you squeeze it and it crumbles, it’s way too dry. Get the hose.

If space is limited, the crank-turned drums are the quickest, most compact way to make compost, Smeenk says. But they’re expensive.

When your compost is crumbly and dark, when you can’t tell any more what the individual elements were, and when it has that good rich smell of forest loam, it should be ready. However, for your own safety and that of your plants, make one last test. Put some of it in a jar, add enough water to make it soggy and screw down the jar lid tightly. Let it ferment out of the sun for a week. Then open the jar carefully (gas will have built up inside), and give it a sniff. If it smells like healthy wet earth, it’s ready. If it stinks, then it’s not decomposed enough and you need to give it more time (and turning).

You’ll save yourself and your plants hard times if you screen the compost before you use it. Half-inch rabbit wire is good for compost to be worked into garden beds. That will take out wood chunks. Toss what’s too big to go through the screen into the next batch of compost. For potting soil, you’ll need your most mature, finest-textured compost. Eighth-inch screening is good here.

Don’t dabble with any liquid running out the bottom of the pile. This is not compost tea. This is runoff that hasn’t broken down yet, and it may be crawling with pathogens.

For compost tea, put your finished compost in an old knee-high stocking, suspend it in a 5-gallon bucket of water, plug in an aquarium bubbler to boost the microorganisms, and cover it with a loose lid for 10-12 hours. Better use the brew at once because it will go flat, like beer, and won’t help you.

Anything carbon-based can be composted, Smeenk says. A Mat-Su organic farmer put a pair of old jeans in his compost pile.

When last seen, only zipper and button were left.

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