Solving Compost Pile Problems
Problems in compost piles are a relative thing. The occasional bad odor in a passive pile behind the barn in a rural area may not be considered to be a "problem", while that same situation in a dense urban neighborhood may have the police at your door. The list of problems addressed in this section then, is offered with the understanding that, for some, many of these items will not be regarded as a serious issue requiring any action whatsoever.
Pile Has Unpleasant Odor -- Bad odors are perhaps the most common problem identified by home composters. Fortunately it is an easy problem to solve. No matter what causes the bad smells, the odors will go away quickly if you turn the pile and add some carbon based materials to the pile as you do so. But what if it is the middle of July and you have no dried leaves and you don't know where to buy straw or hay? Try adding Canadian spaghnum peat moss to the pile. It is sold in bales at all garden centers and works extremely well in eliminating bad odors from a compost pile.
[Line drawing - Showing an odor problem]
Don't just try to cover the odoriferous mess with a layer of leaves or peat moss; the smell will be back in a day or two. You must work the carbon material into the smelly mess in order for the decomposition process to get back into balance and eliminate the odor.
It is important to understand why odor problems occur in order to avoid a recurrence of the situation. Recall from the earlier discussion that bad smells usually develop because the pile has become anaerobic; it has no air. This happens when the pile gets too compacted and soaked with moisture, the water forces out all the air in the pile. Often there is a simultaneous excess of nitrogen materials in the pile; e.g. grass clippings, kitchen garbage, fresh weeds. So guard against piling too many nitrogen materials in the pile without a generous amount of carbon stuff too. Also, take care to cover the pile to protect it from heavy, soaking rain.
Pile Is Too Dry -- If the compost pile gets too dry, decomposition slows. A good signal that this is the problem is that the pile does not settle very much. A pile properly moistened will settle by as much as 20 to 30% in just a month or two. If this does not happen it means that the environment within the pile is lacking moisture so the microbes are not able to work with their typical enthusiasm. Without adequate moisture, microorganisms cease to function and decomposition stops.
[Line drawing - Showing too dry pile]
The best solution is to turn the pile and add water as the pile is rebuilt. The lazy person's solution is to turn a garden hose on just enough to have a modest drip coming out and repeatedly thrust the hose into the pile in various locations and let the water seep into the pile. Just pouring water on top of an established pile usually does not get water into its center, because it just sluices off its outside surfaces. Solve that problem by scooping out a shallow hole in the top of the pile that will trap the water so it can soak into the pile. Then keep the cover off the pile for one or two good rains and the pile should be thoroughly damp again.
Pile Is Too Wet -- If the pile is too wet, for whatever reason, the only solution is to turn the pile and add carbon material. Chopped leaves, peat moss, or straw mixed in with the wet material will help absorb the excess moisture and prevent putrefying. Allowed to simply sit, the wet pile may start to smell. At best, it will take a year to decompose because it lacks air.
[Line drawing - Showing too wet pile]
Pile Is Not Hot -- If the inside of the pile is damp and warm in the middle but is not decomposing to any observable degree, the most likely possibility is that the pile is too small. Unless the pile of material is at least 3x3x3 feet, there is not enough critical mass to support the microbial activity that will generate the high temperatures associated with efficient decomposition. The heat at the center should be almost uncomfortable to the hand.
Pile Is Frozen -- Most composting microbes become inactive below 40ø F. Decomposition continues during the cold months in areas that experience true winter, but very slowly. However, if the pile is turned during the winter and new nitrogen material is added, that pile can easily attain high internal temperatures again and stay quite warm for weeks. Covering the pile with completely with clear plastic film will reduce the oxygen access but will serve as a solar heating mechanism to keep the pile going into the winter. If the pile is quite moist and is not covered this way, it can actually freeze during a cold winter. When spring arrives, the decomposition process will resume. If you are in a hurry you can turn the pile during the winter. If you are not in a hurry, just enjoy spring's arrival and let the microbes take care of themselves.
[Line drawing or photo - Showing maggots in the pile]
Insects In Pile -- Compost piles, by their nature, attract all kinds of bugs and worms. Many beneficial critters such as sow bugs, centipedes, and earthworms inhabit compost piles. In fact, they are instrumental in breaking down the organic yard waste materials. They do not represent a problem and should be encouraged. Houseflies and fruitflies, on the other hand, are not desirable. Their presence suggests that the pile is not properly built or maintained. Take the trouble to prevent these insect pests in the first place, rather than waiting to deal with them when they have already become a problem.
Always cover any kitchen waste that is added to the pile with a layer of carbon material such as chopped leaves or sawdust. A cover over the pile will not keep out flies. The garbage must be covered by that carbon material to be fully protected from marauding flies. If the flies have already arrived and maggots are apparent in and around the pile, turning the pile will often eliminate the problem. Make sure the material on the outside of the pile where the eggs and maggots are end up on the inside of the pile where the heat can kill them.
[Photo - Adding predatory nematodes to pile with maggots]
If you choose, for whatever reason, not to turn the pile, ®MDNM¯and you are not prepared to tolerate maggots, the best and safest pesticides are the natural predators of maggots such as parasitic wasps and predatory nematodes. Available from several mailorder sources (see resources) predatory nematodes will control a maggot problem in a matter of days. Other insecticides including malathion and carbaryl will kill maggots, and the residue from those products will break down within a month or two.
What about pesticide residues? Homeowners worry about putting grass clippings that have been treated with some kind of pesticide on their compost pile. Avoid using any grass in a compost pile that has had any pesticide on it and has not yet been rained on. Typically a steady rain washes all pesticide residues down into the soil around the grass roots and leaves the blades free of pesticide material. If pesticide treated grass is inadvertently included in a compost pile, it is not likely to present any problems. Several studies on the subject suggest that most pesticides used in the home landscape break down during composting, especially if the pile is turned and internal heat exceeds 120øF.ÿ20Those that do show up are generally do so at the low end of the range one would expect to find in typical suburban soil, which often contains pesticide residues.
[Line drawing - Line drawing showing that if grass has been rained on first, it is probably safe for compost]
Animal Pests In The pile -- Occasionally home composters have problems with dogs, cats, raccoons, opossums and even rats hanging around the compost pile. Here again, prevention of these nuisances is preferable to coping with the problem when it arises. None of these animals will be a problem if the pile is built and maintained properly. Those whose habitats are nearby may not even be aware it is there if basic precautions are taken. Obviously, if kitchen garbage is just thrown on top of the pile, and the pile is not covered, those animal pests may well be attracted to it. A good layer of carbon material over the garbage is essential. A strong cover on the bin will also deter them if they are inclined to investigate the pile.