Although maintaining a compost pile is an excellent way to responsibly recycle organic materials, there are some things that you should never try to compost.
First of all, any materials that are chemically or biologically contaminated or may promote disease should be avoided. Materials that attract pests, have a strong smell, or create nuisances should also be similarly shunned.
Don’t throw fish, meat, or dairy products on your compost pile; nor should you add bones. Charcoal ash should be avoided, because the sulfur dioxide in it is dangerous to plants (especially when mixed with water, when it becomes sulfuric acid). In addition, don’t let weeds with seed heads get into your pile, or any material that you’ve cut off an infected plant.