The other day, an Organic Gardening reader emailed us a question about whether or not he should add shredded newspapers to his compost pile. (My opinion: Shredded newspaper is OK in moderation, especially in piles that are blessed with too much nitrogen and need some extra carbon-rich materials to balance it out. In my garden at home I’m more likely to utilize newspapers in an unshredded layer under the mulch, where they have a compounding influence on the mulch’s beneficial effects.)
The reader’s question inspired me to start a list of items that shouldn’t be added to a compost pile. Weeds that have gone to seed; meat scraps from the kitchen; used cat litter: Some things are obviously unwelcome as compost ingredients.
Others require some research. Wood ash, for example, is often considered a safe compost ingredient—in small quantities. But it is highly alkaline and raises the pH of the decomposing pile, allowing nitrogen to be released into the air as ammonia gas. Not just smelly, but a waste of an essential plant nutrient.
In the end, I came up with 10 items that are best kept out of the compost bin. Look for the list in the Skills & Abilities section of the June/July 2011 issue of Organic Gardening. —Doug Hall