Chapter 6

A Compost Problem Solver

When They Please

There’s a compost pile in my backyard,

This heap sets me at my ease;

I turn it every fortnight,

The worms turn it when they please.

Joel Birman
Springfield, Massachusetts

Everyone who makes compost in his or her garden aims for a perfect pile. The objective is composed of the perfect mix of “browns” and “greens” that breaks down into a rich, dark compost. But what if the results are less than perfect? Don’t throw in the trowel. Here are some common compost problems and what to do about them.

Smoking Compost?

In cold weather, or even on a cool morning in summer, an active compost pile will emit steam, causing many beginning composters to think their piles are on fire. Actually, the compost is just releasing its warm, moist breath, which is a good sign of healthy activity inside. Let the pile continue to do its job.

1. Rotting is Not Composting!

While composting does involve decomposition, that does not mean that the compost pile should ever be sopping wet, soggy, slimy, or smelly. Why would a pile rot and not compost? One of three factors is usually to blame: too little air (oxygen), too much moisture, or an overabundance of either “brown” or “green” materials. For example, a compost pile or bin that is overburdened with materials that mat down when wet—grass clippings, spoiled hay, heaps of unshredded leaves—can become so dense that air can’t reach the center of the pile. If a dense pile is left uncovered during a prolonged rainy spell, and if air is not introduced into the pile’s center, it will end up as a cold, soggy (and smelly!) lump. Aerobic bacteria, the tiny microorganisms that make compost “cook,” cannot live in an oxygen-poor environment. On the other hand, anaerobic bacteria love it, since they don’t require air to thrive, but they work much more slowly than aerobic bacteria—taking 2 to 3 years to break down a pile. Unfortunately, the resulting compost will be slimy, soggy, and unpleasant during the long process. Also, an anaerobic compost pile or bin won’t get hot enough to kill any weed seeds it contains.

Fortunately, soggy compost is fairly easy to fix. Use one or more of the following methods, and the pile or bin should heat up nicely within a few days.

Keep Out Water

If relentlessly wet weather is part of the problem, use a loose-fitting lid or tarp over the pile or bin to exclude rain.

Dry It Out and Add Air

It only takes a little effort to rescue a soggy pile.

• Turn and gently fluff the compostables.
• If the contents are really sodden but the weather is dry and sunny, spread the pile all out in a thin layer on the ground to dry a bit before raking it up and rebuilding the pile or refilling the bin.
• Add more compostables to help soak up the excess moisture and correct the ratio of “browns” to “greens.” A quick sniff will indicate which is needed: If it smells rotten and lots of flies are buzzing around it, chances are that too much dense, wet stuff—such as kitchen scraps or canning wastes—are in the pile. Simply turning and drying may be enough to correct the problem. Or mix in both some dry “browns,” such as chopped straw or shredded old leaves, and some dry “greens,” such as alfalfa pellets or dried grass clippings, to help dry things out.
• At certain times of year (fall and winter), “browns” are available in abundance but “greens” may be scarce. Hair from a pet groomer or barber is available year-round, as are alfalfa pellets or soybean meal from a farm-supply company. Some gardeners tap into a renewable source of a high-nitrogen “green”: urine. It’s normally sterile, and if the gross-out factor isn’t an issue, it’s an effective way to get fall leaves “cooking.” Just dilute urine with water 1:10 and sprinkle it on shredded leaves.
• If the compost has the sharp stench of ammonia, the mix contains too much green material, such as fresh grass clippings. Mix in some absorbent brown materials such as chopped straw or shredded leaves to absorb excess moisture and correct the “greens-to-browns” balance.
• At certain times of year, especially in spring and summer, “greens” are available in abundance but “browns” may be scarcer. Shredded office paper or newspaper are readily available year-round and can be used as “browns.” Or buy wood-shaving bedding (aspen wood is good and pine is okay, but avoid cedar) or straw at a farm-supply company.
• If the compost has little smell and most of the materials added were “browns,” mix in some dry “greens,” such as alfalfa pellets or dried grass clippings, to dry things out and correct the balance.

Help the Good Microorganisms Win

A one-time sprinkling of gypsum or lime may be useful when correcting a soggy compost pile or bin. Both are salts and will shut down the growth of anaerobic microorganisms. Sprinkle a small amount of one or the other (no more than a quarter-cup for the average home compost pile or bin) over the compost, while turning the contents gently. The gypsum or lime, plus the drying and aerating action of turning, will help the beneficial aerobic soil organisms in the pile return to a healthy balance. A word of caution: Do not apply gypsum or lime to a healthy compost pile.

2. Dry and Dusty Piles at a Standstill

In areas where rainfall is practically nonexistent, or during a particularly dry season, a compost pile or bin may not receive enough moisture to support the microbial life necessary to fuel the composting process—without some help. Luckily, fixing dry and dusty or dormant compost is very simple, if outdoor temperatures are above freezing.

Test for Moisture

A compost pile with exposed sides may need to be watered if the top 4 inches of the mound dry out during a heat wave. Turning and watering a dormant pile should bring it to life within a few days.

Reach a bare hand into the pile and give the materials a squeeze. If things feel dry, all the pile may need is some water. Put a small sprinkler set on low or a coiled soaker hose on top of the pile or bin and run it for an hour or so. An open hose can also be used, but there will be considerable runoff, and the interior of the pile may remain dry; be sure to move the hose frequently and allow the water to enter the pile at various places. Check the center of the pile to be sure it’s becoming moist. If it’s not moist to the interior of the pile, the pile may need to be rebuilt and watered. If the compostables feel about as wet as a damp sponge, yet the pile or bin doesn’t heat up within a few days to a week, chances are the initial ingredient mix was mostly brown and too short on green materials. Rebuild the pile and mix in some high-nitrogen “greens,” such as manure or grass clippings.

Once the pile does start “cooking,” don’t let it dry out again. Tiny microorganisms use up a lot of water as they multiply, so keeping the pile moist will keep the decomposition process active.

Streaky Compost

A pile or bin that has the right amount of air and moisture, but lots of extra nitrogen, may compost so fast that the center overheats and dries out, leaving visible white streaks. These white streaks that appear early in the composting process are sometimes called “fire fanging” or “burning” by old-time gardeners. This phenomenon is especially common in piles that have been overloaded with fresh manure—especially from chickens or horses. The white streaks are not ashes but actually the dead bodies of millions of microorganisms. While not dangerous, fire fanging means that the microorganisms are no longer making finished compost due to excessive heat in the pile. To prevent overheating in a pile, turn and mix the materials regularly and maintain a good mix of “browns” and “greens.” To correct an already fire-fanged pile, rebuild it completely, mixing in some brown material, such as shredded leaves or paper, and sprinkling lightly with water as needed.

In contrast, the white powdery material present in nearly finished compost is most likely filaments produced by fungi and actinomycetes (a type of bacteria). Both of these microorganisms work on breaking down debris that is tough, dry, and low in nitrogen, during the cool final stages of the composting process. The white powdery material is harmless and just shows the compost isn’t completely finished.

3. Uninvited Guests

The dark, warm conditions or tantalizing aroma of compost can sometimes result in uninvited guests, such as a variety of insects and other small creatures as well as larger animals. Here are some of the most common pests and what to do about them.

Insects and Other Critters

A compost pile is a smorgasbord to creatures like pill bugs and sow bugs (which are actually small crustaceans and not insects), because they live on decaying organic refuse. Turning over the top layer of almost any pile will reveal thousands of tiny gray creatures that look like miniature armadillos with seven pairs of legs each. These pill bugs and sow bugs look similar, but their one difference is that pill bugs roll up into a ball when threatened and sow bugs don’t. Neither bug will harm compost—in fact, they’re actually helping to break it down. But if pill bugs or sow bugs are in the finished mixture when it gets spread on the garden, they may turn to snipping off the emerging roots and leaves from beans, beets, and other seedlings, making them dubious helpers at best. Some gardeners remove compost from a bin or pile and let it set for a few days to allow the pill bugs and sow bugs to leave before the finished compost is added to the garden.

Ants and earwigs, which are true insects, may also invade compost. Like pill bugs and sow bugs, they are essentially harmless to the composting process, but their presence may indicate that a pile or bin is on a slow track to decomposition. To evict these small residents from the compost, raise the heap’s temperature to above 120°F (so hot that a bare hand can’t tolerate it for very long). To heat up compost, turn the pile over and rebuild it, watering as needed. To prevent the bugs from moving back, keep the compost “cooking” by turning it at least every week or two until it’s finished.

If finished compost is infested, just spread the compost in a thin layer on a tarp in direct sunlight and leave it there to dry for a few hours. The unwanted bugs will bail out quickly.

Large Furry Visitors

Large visitors, such as raccoons, opossums, skunks, dogs, and bears, do not eat compost, but they will tear up the pile, and even the bin, to get at any fresh, edible kitchen garbage. Items such as meat scraps, fat, or bones are especially attractive to these compost raiders, and even more so if these favorites were recently added. Animals can be attracted to compost piles just because the piles smell like humans, and the animals have learned to associate humans with food.

Completely avoid tossing meat and dairy products into the compost pile, and be sure to mix all newly added kitchen garbage into the hot center of the pile to discourage animals. Unfortunately, once scavengers have gotten used to stopping in for a free meal, even if it’s peelings and crusts, the only solution is to install a sturdy covered bin. An off-the-ground model, such as a compost tumbler on a stand, or a homemade scavenger-proof garbage-can composter are the most effective choices. But determined animals can be destructive when they’re hungry, so dismantling and abandoning a compost pile for a few months may force pests to search elsewhere for a free meal.

Small Furry Creatures

Moles, voles, mice, and rats may be more of a problem for most backyard composters. If there are tunnels in the compost pile, the chances are that a tiny four-footed creature is dining on kitchen scraps. These small rodents can tunnel under or climb over a bin’s structure or walls, can squeeze through the tiniest of gaps in the bin, and can even take up residence in the middle of the pile. If mice and moles and their friends are a constant issue, take steps to exclude these animals when building or setting up the bin. Try setting mousetraps along the bin perimeter to try to reduce rodent populations. Install hardware cloth or wire mesh on the bottom, sides, or top of the bin to create a barrier. Unfortunately, this could make adding to or maintaining the pile more difficult, but it might offer the best solution. Or consider using the bin for yard waste only and stop adding kitchen scraps—at least until the pests have moved on.