"Your #1 source for information about how to compost."
HOW TO COMPOST
What a Good Pile Needs
What You Need
Extras & Additives
What to Use - or Not!
Building the Pile
When is it Finished?
Just Do It
More Than Just Dirt
Water & Soil Remediation
A Few Concerns
What You Can Do
Additives, Accelerators & ExtrasIf you want a hot pile, and you want it now, any of several compost boosters or inoculants will help speed the process.
Since most piles are short on nitrogen, not carbon, adding nitrogen will generally help a pile heat up quickly. (If the pile starts smelling like ammonia, you know you've gone too far.) Quick fix nitrogen sources include blood meal, organic cotton-seed meal (non-organic can contain high concentrations of pesticides), alfalfa pellets, and manures, especially chicken manure. Sprinkle, don't dump, one of these here and there in the pile as it accumulates. Doing so is one way to get a continuous pile to heat up.
Since it's the micro-organisms that do the bulk of the work in an active pile, adding extras will hurry the process along. Most organic gardening stores carry boxed dormant micro-organisms. Dig down a layer or two, and sprinkle some of the dry mix into the damp center of the pile, in several different places. If you put it on top, be sure to water it in as it won't become active until damp.
Placing a palette in the bottom of a compost bin, or simply starting the pile with several inches of sticks or heavy-duty stems, will lift the pile off the ground and provide continuous air-flow. Doing this, however, removes the compost from what's often the primary source of microbes, the dirt underneath it. It's a good idea, therefore, to provide an alternative source of microbes for piles built off the ground, if only by sprinkling them with the occasional half-inch of dirt.
Oxygen can also be supplied by building a pile around perforated pipes that reach all the way to the sides or to the top of the pile. There's some dispute in the composting world about how well such systems work.
Turning, however, is the time-honored method of providing oxygen to a pile.
Smaller pieces provide more surface area for the micro-organisms to attack. If you chop, shred, or grind your compostable materials before adding them to the pile, you in effect do some of the beasties' work for them, which saves time.
Some people toss the day's compost into a food processor or grinder; some use a paper-shredder on newsprint and office paper; some use chippers or a machete on twigs and branches; some use a mulching lawn-mower to shred leaves and other compostables.
Some people include lime in their compost to raise pH. Immature compost can indeed be quite acidic -- the process produces many acids -- but by the time it is fully mature, its pH is about 6.5, which is ideal for most plants. Adding lime can harm some of the micro-organisms that create compost, and unbalance the complicated chemistry. The early, acidic phase, for instance, plays an important role in killing dangerous pathogens. It's best to adjust compost pH after the composting process is finished, but if your starting mix has a pH of 5 or below, you can add lime.
Wood ash can be a valuable soil amendment for acidic soils, especially if you're getting it free: it contains phosphorus (.8-3%,) potassium (2.8-8.6%), and calcium (14-28 %), as well as magnesium, sulfur, and boron. Some people figure they'll just toss the ashes in the compost and save themselves the trouble of dealing with two separate amendments.
However, adding ash to an open compost pile doesn't work well because its nutrients easily leach away. This is due in part to its chemistry and, in part, to the small size of its particles. Those particles themselves are subject to leaching, and because they're so small, ash has a high surface area which exposes a high proportion of its contents to water when it gets wet.
Even in a closed pile, ash is a bad idea. Its high calcium content makes it a powerful "liming" agent. Like lime, it interferes with the natural pH of compost. Changing pH changes everything; to mess with it is to mess with the chemistry of the pile.
Instead of adding ash to an active pile, add it to finished compost near the end of the curing process, at which point it will not derail any important chemical or biological processes.
In Praise of LidsLids are not required, and plenty of people compost happily and successfully without them. However, a lid solves so many problems that it's worth considering even if you don't want a bin to go under it.
A lid performs two important functions: it keeps rainwater off, and it keeps critters out.
A rain heavy enough to significantly wet a pile will cause water to drain from it, and this leachate will carry with it valuable microbes and minerals. Rain water will also cool the compost, slowing the composting process. Worst of all, if the pile stays wet for too long, the aerobic microbes might give up and pass the baton to their anaerobic cousins, which would mean that the compost pile "goes anaerobic" -- which means that it starts to smell.
Lids not only keep water out, but to some extent they also keep it in, slowing evaporation from the pile in hot weather. Many piles plug along at half speed or even grind to a halt because they're not wet enough.
Mother Nature, of course, doesn't put lids over her leaf piles, but she also doesn't care if they go anaerobic or if their nutrients leach away.
The second function of lids, critter-control, eliminates several problems that range from the trivial to the critical. Animals that invade compost piles in search of food (magpies, squirrels, foxes, crows, raccoons, possums, skunks) deplete the piles we depend on to nourish our gardens. Some, such as skunks, are not visitors we want to encourage. Crows and magpies, once they've located a prime pile, can congregate in large, loud groups. Foxes pose a danger to our chickens and cats. And so on down the list.
These visitors may leave behind feces in place of the foodstuffs they forage; cats and dogs may also take a bathroom break in or on a compost pile. Bird droppings may contain weed seeds, including those to the dreaded nut sedge, while other animal feces can carry pathogens, including quite nasty ones such as E. coli and salmonella. Stray or free-ranging dogs (or deer) that take a fancy to your compost pile aren't the only possible sources of E. coli, but the threat they pose is real, and an enclosed bin with a lid all but eliminates it.
Lids don't require hours of work with saws and hinges, but what might seem the simplest solution -- throwing a tarp over the whole pile -- could again result in a smelly, anaerobic mess, especially if the pile is wet when it gets covered. Unlike a lid on a bin built of chicken wire, tarps rest directly on the pile and drape over sides. Since they cut air-flow pretty drastically, they're best used only in composting emergencies.
On the other hand, a few boards laid over a bin will get the job done. Just shove one aside when it's time to add table scraps. Turning does require removing and replacing them all; if that gets to feeling like too much of a chore, it may be time for an upgrade.