composting basics

sifting-compost-2HERE, IN THE COMPOST HEAP, is life and death and life again—proof positive of “from dust to dust.” But too many gardeners waste the raw material of future soil amendments by getting hung up on silly details, like what shape of pile or kind of bin to use, what can and can’t go in the pile, or how much work they fear composting will be. It doesn’t have to be much work at all; even without turning and other human intervention, the leaves on the forest floor break themselves down in time, don’t they? So will your pile, if it’s made sensibly.

What method of composting you use should be determined by the volume of material created in the yard (and to a lesser degree, in the kitchen, where vegetable scraps, egg shells and coffee and tea grounds can be collected for the heap, too). My friend and fellow garden author Lee Reich has lots of material to recycle, and believes in using bins–so he has a whole highly productive row of them, like this, in his yard.

I create far too much raw material for a simple bin-type system, the commercially available kind made of metal or heavy plastic or mesh that are about as big as a washing machine. I have one of those, a metal one that shuts tight and thereby keeps animals out, to hold my vegetable food wastes, alternating them with layers of garden debris and a little soil or finished compost to get things activated and reduce any chance of unpleasant odors. I haven’t managed to build multiple bins as Lee did–yet.

One recent rage is all about lobster-trap-wire bins, meaning really durable even under the ocean day in and out. But my main heap is about 40 feet long and 5 or 6 feet wide, a long, open pile that in composting jargon is called a windrow. In the peak of fall cleanup and leaf raking, it gets to be about 5 feet tall, too, but as the material begins to settle, and eventually to break down, it’s usually more like 3 to 4 feet high.

Whatever style of composting you choose, from a simple, small pile to a long windrow to an enclosed store-bought bin or row of bins, the key is to vary the kinds of materials that go into the mix. There is no precise recipe; there is just common sense at work here, too.

My compost heap in late fallGreen plus brown equals black gold (well, plus some sticks and stones you will have to screen out, above). Layer the two basic categories of ingredients: green ones (nitrogen-rich materials such as grass clippings and leafy green plants) and brown ones (carbon-rich materials like dry, brown leaves or twiggy bits and pieces). Too much of either one will impede decomposition.

I liken successful composting to the combustion that goes on when my car is running smoothly: to ignite, the car needs fuel, air, and a spark. So does the compost heap. The spark is the nitrogen-rich green stuff; the fuel is the brown stuff; the air is supplied by occasional turning of the pile, and water must be available from rain or the hose, so the pile is slightly moist but not sodden.

Too much green stuff (particularly wet things like grass clippings) will produce a smelly heap; spread them around, and toss in a thin layer of soil or old compost to help things get going. I don’t bother with store-bought compost starters; there are plenty of beneficial micro-organisms in good garden soil and some well-rotted leaves.

Too much brown stuff will just sit there (and that includes things that are “brown” chemically if not in color, like piles of orange rinds from weeks of juicing). Chopping up difficult brown elements will speed decomposition; so will aerating the pile, and adding more greens. And don’t site the heap in the dark; a position in at least part-day sun is essential to good decomposition.

It’s easier to list what doesn’t go in the heap than what does. Leave out weeds with seeds on them (pull them before they go to flower and seed, when they can be composted); weeds that spread even without seeds (like bulbous onion grass); and diseased plants. All of these can be pre-“cooked” first in some big plastic bags near the heap, to kill off the unwanted parts, though again, Lee Reich puts it all in his bins. We both leave out fats and oils, such as dairy products and meats and fish; bones.

Manures from farm animals (not domestic pets) are great additions to the heap, if you can get them from a nearby farm or stable that practices organic agriculture and doesn’t feed tainted grasses or grains to their animals. Otherwise, because of “persistent herbicides” sprayed on fields, you may end up with “killer compost,” that causes your plants not to grow.

Also remember that unless manures are well-composted in a fast-decomposing (or “hot”) pile, between 140 and 160 degrees F, they will be full of the seeds of what the animals were fed, so plan to let them rot thoroughly in a heap that’s really cooking along. A compost thermometer will help eliminate the guesswork here. That said, I will admit I put most weeds in my heap (not bagging them up for the trash) and that I never take my heap’s temperature. Nobody is perfect.

a place just for leaves

If you want to use compost as mulch later on, I recommend composting leaves separately, in their own pile. They can be shredded to speed up the process; this can be done if they are raked into small piles where the heap is to be made, then run over with the mower, which works better when they are dry. Moisten the pile and perhaps sprinkle in some soil or old compost. The leaves can also be left whole, in bags or in a pile, all winter and shredded come spring.

Leaf mold, as the rotted stuff is called, is a great mulch or soil amendment. How often you turn your pile will affect the speed at which finished material is ready to be returned to the garden; if you’ve got time, you can escape turning and just let nature take its course (again, nobody’s perfect—and would you like to turn a 40-foot-long windrow every few weeks?). I turn once or twice a year, in spring and late summer or fall, and extract the lowest layer, where the finished stuff is hiding. After 20 years of doing this by hand, I recently treated myself to a small tractor with a front-end loader, and the work will be easier from now on.

sifting compost Before using the compost in the garden, I toss it through a homemade sifter (seen above, like a giant easel with hardware cloth where the drawing paper or canvas would be). It lands in a wheelbarrow, and this action culls the stones and sticks and unfinished bits like tenacious corncobs or thick roots. I topdress my flower beds with an inch or two of the sifted material each spring, along with some all-natural organic fertilizer, and use the rest to top up my raised vegetable-garden beds. Yummy.

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