Kitchen Gardening

Creating Healthy Compost

Should you compost pesticides, herbicides, animal manure, paper, weeds, or diseased plants? The answers may surprise you.

A compost pile is the perfect place to recycle kitchen scraps.
Photo/Illustration: Scott Phillips

by Janet M. Jemmott
August 1999
from issue #22

Theoretically, anything of organic origin can be put into a composting system, but I would not recommend adding meat, fish, poultry, or foods with added fat to an open system. They’re just too likely to attract pests. Besides, they can be odorous and slow to break down.

Composting kitchen scraps
  When you add kitchen scraps to a compost heap, make sure you mix brown and green material. Completely cover good waste with brown matter.

If you have a closed system and want to add waste of animal origin, such as bones or food scraps, you must bury it in the center of the pile and cover it with brown material; you should also have a layer of brown material around the outside. Deterring rodents has to do as much with how you manage the bins as with their contents and the con­struction of the bin itself.

Evidence indicates that pesticides and herbicides break down into innocuous components during hot composting. Nevertheless, I would not put treated grass clippings in my compost system.

Animal manure
Horse and cow manure are tradi­tional additions to compost, and fresh manure provides a large input of nitrogen. Use one part fresh manure to four parts brown organic matter. Give it plenty of time to break down.

Keep cat, dog, and human feces out of your bin, as they may contain harmful pathogens. Bird cage waste typically includes numerous weed seeds and possibly diseases, so keep it out. Any manure can contain pathogens. The concern is not only whether pathogens will break down in the compost, but also that you may come in contact with pathogens when handling waste to put in the bin. This is of less concern with manure from herbivores such as rabbits. Rabbit droppings are a rich source of nitrogen. Handled carefully, they can fire up a waning compost mix.

Most newspapers are printed with soy-based inks and are safe to add to your pile. Use them in mode­ration and shred them first. If you run out of brown matter during the winter, paper is a good stand-in. Do not add shiny, colored maga­zine paper, because the ink may contain heavy metals.

Weeds and diseased plants
Do not add diseased plants to compost. If you’re certain you have your pile cooking at 150° to 160°F for at least a few days, weed seeds will be destroyed. Certain pernicious weeds may persist in any but the hottest compost piles.

If you’re new to com­posting, keep it simple. Stick to kitchen waste and back­yard clippings. Or follow the guide below.

Good stuff to compost Bad stuff to compost

• Leaves, fresh or dry
• Grass clippings
• Weeds
• Pine needles
• Seaweed
• Shredded wood, shavings and sawdust from untreated wood
• Brown paper or newspaper, shredded
• Vegetable and fruit waste
• Tea and coffee grinds (including bags and filter paper)
• Egg shells
• Manure of herbivorous animals, including rabbits, horses, cows  

• Diseased plants
• Pesticide-treated leaves and grass clippings
• Poison sumac and poison ivy
• Glossy paper
• Pressure treated wood scraps and sawdust
• Kitchen waste of animal origin*
• Human feces, pet manure**

*Kitchen waste such as meat scraps, bones, and dairy products can be composted if a pile is carefully managed, but these products are slow to decompose and attract pests.

**There are folks who successfully compost human fecal matter, as well as those of cats, dogs, and other carnivorous pets. High temperatures may kill off pathogens and parasites, but in the case of the home composter, the risks are not worth the bother.


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