Stop Toxic Compost

Creating compost is a great way to recycle yard and kitchen waste and to make a free soil amendment at the same time. Starting a pile and making your own compost can be a fairly easy and low-maintenance process. However, there are some precautions you need to take to make sure that your compost doesn't go from being a garden asset to a toxic pile of goo.

Be careful of the materials you are putting into your compost bin. Most kitchen waste items are good for your compost pile. However, there are some that are definite no-no's: meat, fish, dairy products, and oily or greasy food waste. While most of these food waste items won't necessarily make your compost pile toxic, they are slow to break down, tend to attract animals and pests, and smell really bad when they decompose. The one item that can be toxic is raw meat or fish - adding this to you pile is one way to get your compost full of salmonella very, very fast.

Be mindful of the yard waste that you add to your compost pile as well. Putting diseased plants into your compost will make all that great organic matter into a disease vector for all the plants you put it next to next season. It takes a very efficient and hot running compost pile to destroy plant diseases. This is also why you shouldn't put cat or dog waste in your compost either. While manure from vegetarian animals like cows or horses is just fine to compost, dog and cat droppings contain disease organisms that the average household compost pile just isn't hot enough to kill.

Another yard waste issue is herbicides and pesticides. Don't add anything to your pile that's been treated with synthetic chemicals. They don't necessarily break down in the composting process, which means they can pass on intact into your garden. While pesticides may have been useful for getting rid of dandelions that infested your lawn last summer, you don't want it to migrate to your vegetable garden or your prize roses. If you still want to add materials that have been treated with pesticides, let them sit in a pile outside your compost bin for two to three weeks before adding them in.

Some more yard waste materials to avoid are leaves from horse chestnut trees or any type of walnut tree. Both contain chemicals that inhibit germination and plant growth. If you do feel like you want to use these in your compost, only add them in small amounts and mix the leaves thoroughly into your pile. The toxins in the leaves will break down within a month or so.

Other assorted materials to avoid are glossy paper, charcoal briquettes, coal ash and manure from farm animals that have been recently treated with antibiotics. Glossy paper is much more likely than newspaper to contain toxic inks or heavy metals. Most newspapers are safe to use in your compost pile because they are now printed with soy or vegetable inks, but please double-check! There is often a little blurb about how the inks are vegetable or soy based at the bottom of the first page of the paper. Otherwise, call the newspaper office and ask.

Coal ash or charcoal briquettes should be avoided because they contain sulfur oxides in amounts high enough to damage your plants. However, wood ash is useful for making the pH of your compost pile more alkaline. Manure is a great addition to a compost pile as long as the animals it came from haven't been recently treated with antibiotics. Try and find a local source of manure that you can guarantee is antibiotic free - an organic farm is one good option.

The last piece of advice I have is to make sure you manage your compost pile properly. An ill-tended compost pile will be a stinky pile of glop no matter what you put in it. A well-tended and material-balanced compost pile will be earthy-smelling throughout the composting process and will become a great organic soil amendment once it's done. See the links below for more pointers on good management of your compost pile.