Compost
There are two big reasons to make compost.
First, it’s kind to the earth. What are the alternatives for your kitchen scraps? In Arlington, like many towns nowadays, trash is trucked off to an incinerator. Most kitchen scraps are full of water, so they are heavy to truck and then require a lot of supplemental fuel to burn. Or you can put kitchen scraps down your garbage disposal. Then the local sewage treatment plant has to use energy pulling their nutrients back out of the water before it is discharged.
One of the simplest ways to reduce your household’s fuel use, therefore, is to have a compost bin for kitchen scraps. You won’t have to empty it very often at all. Since kitchen scraps are mostly water, their volume decreases dramatically in a compost bin and many households find they can use a bin for a year or two or even three without emptying it.
Yard waste in Arlington gets trucked to Lexington, where it is composted and then distributed to anyone who wants it. That’s not as bad, but if you have space you can skip the trucking and distributing parts of the process by composting your own yard waste in your own yard.
The second big reason to make compost is to increase the fertility of your garden. There is absolutely nothing better than compost for nurturing healthy plants.
Compost can be used in many ways:
My favorite way to use compost is as a mulch. That’s the way nature fertilizes soil, after all – things fall on top of the soil, and earthworms and ants and other burrowing creatures gradually mix it into the soil. Let nature do the work for you!
You can spread up to 2” of compost at a time on an established garden, shrubs, etc. Or heap it on a veggie bed. If you spread compost on your veggie bed in the fall, you can use 8” or more and let it settle in over the winter.
If your compost is well-finished, or you run it through a screen, you can sprinkle it on your lawn. Or sprinkle it on a ground cover. Even if some clumps are visible when you’re done most of them will disappear within a week or so as the critters do their work.
It’s fine to use even unfinished compost as a mulch, if the aesthetics are OK with you. Just don’t add more than 2” of unfinished compost at a time. If it’s slightly smelly, you’ll find the smell disappears within a day or less. (Bad smells mean there’s too little oxygen, and as soon as you spread out the compost it will have plenty of oxygen.) And often half-finished compost isn’t smelly at all, but dark and rich and textured.
People sometimes warn against using unfinished compost as mulch, for fear that the continuing decay process will steal nitrogen from the soil and hurt the plants. In fact, this nitrogen-stealing effect occurs just at the very surface of the soil, in the top quarter-inch or less, so it affects only sprouting seeds (e.g., weeds), but not established root systems. This is part of how mulch deters weed growth, so it’s nothing to worry about!
One common use is to dig compost into planting holes. The problem with this approach is that a plant’s roots may never go outside the planting hole if the soil inside is a lot more appealing than the soil outside. If you put compost in a planting hole, make sure it’s a big planting hole – 3 or 4 feet wide, and down to the bedrock or subsoil. And make sure the compost is well-finished – it isn’t kind to ask the roots of a newly-transplanted plant to cope with unfinished compost.
Another common use is to dig compost into a veggie garden. That’s great, but it can be labor-intensive. It’s best done in the fall, or at least two weeks before planting seeds, especially if you’re using your own home-made compost.
If you are starting a new garden bed, I suggest purchasing bulk compost and spreading at least 6-8” of compost over the entire bed. See additional information on purchasing bulk compost here and on starting a new garden here.
Making compost can be simple or complex:
There’s a lot of advice out there about how to make compost, and people are sometimes intimidated by the complexity of it all. But there’s no need to make it so complicated!
If you want to get finished compost as quickly as possible, you need to optimize the process. But if you just want to take care of your kitchen scraps yourself, and make some compost for your garden, you don’t have to turn composting into a competitive sport that requires extensive study and care and attention.
Here are the basics that I think you need to know:
Compost needs four basic things:
1. Bacteria and fungi, to drive the decaying process
2. Food for the bacteria and fungi – kitchen scraps, leaves, other yard waste, etc.
3. Air – more specifically, oxygen, so the good bacteria can breathe
4. Water, so the whole thing doesn’t dry out
That’s it. Earthworms are helpful but not necessary. You might also want a container for aesthetic reasons, or to keep the critters out of your compost. But only these four things are truly required.
If you are starting a new compost pile, find some good rich soil/compost and add a few handfuls of it to the pile. This will inoculate the pile with good bacteria and fungi. Commercial inoculants can do the same thing, but they are more expensive and I suspect less reliable. This step is pretty much essential for a bin that doesn’t touch the ground, but useful for any pile to get the process off to a good start.
It is also useful but not essential to add earthworms to a bin that doesn’t touch the ground. They generally make it through the winter in my composter, but that isn’t to be counted on.
People often worry about compost being smelly. The basic deal here is that there are two types of bacteria – ones that breathe oxygen like we do (called aerobic bacteria) and ones that are killed by the presence of oxygen (called anaerobic bacteria). Because we need oxygen, we tend to feel repulsed by the smells produced by bacteria that grow in the absence of oxygen. If a compost heap smells unpleasant, therefore, the reason is that it needs more exposure to air.
One solution is to stir the compost. A rotating compost bin makes this easy, but you can also just use a pitchfork or something of the sort.
Or you can do prevention, which means keeping air passages in your compost. Think about how a bag of grass clippings smells after a couple days. The grass clippings are all the same basic shape, so they compress well, so no air can get in, so the anaerobic bacteria take off. Phew!
If, however, you layered the grass clippings with other things, they wouldn’t be able to get compacted in the same way. Follow 2-3 inches of fresh grass clippings with some stems from flowers you picked and enjoyed indoors or deadheaded after they bloomed outdoors, or some twigs that fell off a tree, or some leaves from last fall, or some crumpled newspaper (just don’t use the glossy pages) or torn-up cardboard, or anything else coarse and loose that will keep air flowing.
This can be called “layering greens and browns,” and some people will argue over which precise proportions are best. I don’t care about the proportions. Just cover your grass clippings and kitchen scraps with something else and you’ll be fine. It’s traditional to keep a bag or two of fall leaves next to the composter, and add a few handfuls whenever you feel the impulse. You can also add some good garden soil every now and then, to inoculate that part of the pile.
Some things don’t belong in compost:
Invasive plants, especially seeds and roots. Send them to the incinerator.
Feces from carnivores. Used bedding from rodents and other herbivores, however, is great.
Chunks of fat. The good bacteria can’t digest fat, so chunks will slow down the composting process. Don’t worry, though, about small bits mixed with other foods.
Chunks of meat. Meat attracts animals and can stink. If, however, you have a fully-enclosed metal composter (not plastic!), then small bits of meat are OK and full of useful nitrogen.
Lime. The composting environment needs to be acid. The good bacteria produce acids in order to digest their food, and then the compost naturally becomes less acid as it matures. If you add lime, you are fighting against your allies. If your garden is too acid, add lime to the garden or to the compost just before you spread it, not earlier than that.
A compost pile can have many types of structures:
None. Just pile everything in a back corner of your yard, and let it go to.
A leaf pile. In the fall, rake all your leaves into one big pile. For the rest of the year, tuck kitchen waste and garden waste under the leaves in random locations. Come fall, make a second big pile of leaves and use it in the following year. After a year of being left alone, the first pile should be decent compost.
Home-built. Use straw bales, hay bales, saplings, wire, or anything else you have around to provide some structure for your pile.
Garden-direct. If you have a nice big garden, you can dig kitchen waste directly into the garden soil in fallow spots, or tuck it under your mulch.
Municipally distributed. Many municipalities nowadays sell composters at a discount or even give them away. Check with your Town Hall or DPW. (In Arlington, call 781-316-3108 to inquire about current availability.)
Commercially purchased bin. If you get a bin with no top, put only leaves and other garden matter into it, since animals will gladly take away your kitchen waste and that gets messy.
Commercially purchased rotating composter. A handle, axle, and gears make it easy to keep your compost well aerated. Be aware, however, that turning something near ground level can be back-straining, so something on a stand may be preferable.
In my opinion, the best composter on the market is the double-barrel rotating composter from Mantis. It turns easily, with its handle at a normal standing height. It has two bins, so you fill one up and let it cook while you fill the other one, then empty the first and start over again. (If you optimize conditions, it really can make finished compost in less than two months – I’ve done so. Usually, though, conditions aren’t optimal and cooking takes longer.) It’s made out of metal, so critters simply can’t get into it. It isn’t cheap, but it’s durable and good-looking, as composters go.
For information about purchasing compost, see Garden Supplies.
Next page: Mulch