If someone has put a chemical on the clippings to kill members of the soil food chain, then including those clippings in my pile would kill decomposers.
Organic material that would be fine for home composting in its original state could be processed in such a way that it should no longer be included in a compost pile. Grass, wood, and paper are good examples.
Pesticides, Weed Killers or Fertilizers Applied. Some composters choose to compost grass clipping that have recently been treated with pesticides, weed killer or non-organic fertilizers. I don’t include treated grass clippings in my pile. My reasons for not including these clippings stem from a variety of issues.
Most chemical applications in my area are performed by professional servicers, and the homeowner is not exactly certain what was applied. Even when the homeowner applied the chemicals, they often throw away the empty container and forget exactly what they administered. If I don’t know what was applied, how can I possibly determine that it is safe in my compost pile? I can’t, so I exclude the clippings.
If I could determine exactly what was applied and when, I could research how long the chemical remained potent — if it is absorbed into the plants, if it was likely washed away over time, how dangerous the chemical is, what by-products are produced as it breaks down, etc. Then I could make an informed decision if I wanted to. In reality, if I were worried enough to do all that research, I would be hesitant to use the clippings no matter what I discovered.
The most obvious reason I don’t include pesticide-treated clippings is that it doesn’t make sense to me. If someone has put a chemical on the clippings to kill members of the soil food chain, then including those clippings in my pile would kill decomposers. If I’m going to kill the decomposers, why bother building a pile?
The exception to this general rule would be a fertilizer that had no detrimental effect on soil life. When I apply fertilizer of any kind to my soil I make sure to check for earthworms afterward to see the effect.
If I’m not certain that a fertilizer is entirely organic, I test it first on just one small area. I wait a few days, then dig around to see how many worms are there. If I don’t see any worms, I don’t use the fertilizer. But if the earthworms are happy with it, I don’t worry about using it and will probably use the clippings in the pile.
Some people feel office paper has been too highly-treated to go in their home piles. I have decided that I will include these in my own pile because they comprise such a small portion of the pile.
Non-Organic or Detrimental Substances Added. If organic material has been processed, usually to make it more marketable, it is important to determine what has been done and what substances have been added. The best examples of this are paper and wood products.
Paper is usually listed as an acceptable compost input, but you have to consider different types of paper. Newspaper printed with vegetable inks should be very safe in a pile. On the other hand, I wouldn’t tear up glossy photos and put them in a pile because the paper they are printed on has been heavily processed with chemicals that are not beneficial to compost.
There are so many different kinds of paper, paperboard, and cardboard products, inks, finishes, and glues that it would be impossible to list them all. In theory, we should find out what processes the paper product has been through, what chemicals were involved, then research those chemicals. That would be the safest course of action.
In real life, I don’t have time to research every piece of paper that comes into my home. So, what I personally have decided to do with paper is to abide by the priorities of sustainability. That means that I re-use as much as possible, e.g., donating books to charities, selling to used book stores, reusing boxes. Of what is left, I recycle everything that can be recycled unless it is confidential or identity-sensitive, e.g., letters, envelopes, newspapers, magazines, paperboard, cardboard.
The confidential or identity-sensitive papers are shredded and composted. This is usually some type of office paper, which some people feel has been too highly-treated to go in their home piles. I have decided that I will include these in my own pile because they comprise such a small portion of the pile. I feel that the presence of any chemicals would be “diluted” throughout the pile, so the risk is acceptable to me. I would not be willing to compost them if the quantity was high; fortunately for me, recycling for all kinds of paper is available in my area.
Lumber is another interesting material. Wood from a healthy tree would be an organic material suited for a pile. But depending on the paint, varnish, lacquer, stain, glue, or other chemical applied to it, it may no longer be suitable.
Again, try to determine what processes have been used on the wood product and what chemicals have been applied before deciding if you want to include it in your pile.
Something else to watch for in the future are non-organic products that look like wood but are not really wood or not totally wood. There are floor coverings that appear to be wood, but aren’t. There are decking and fencing materials that are a composite of plastic and wood. The better technology becomes at “fooling” us, the more careful we will have to be to keep the non-organics out of our piles.
Mary Tynes, Master Composter, www.mastercomposter.com
Image Credit (top left): http://www.flickr.com/photos/newtown_grafitti/4453863220/
Image Credit (bottom right): http://www.flickr.com/photos/cliffbeckwith/2541593003/
Great site. A lot of useful information here. I’m sending it to some friends!