ATTRA Question of the Week

K.K.
Kansas

Answer: I am pleased to provide you with information on using composted zoo manure for gardening.

Based on current compost research, most studies show that applying composted manures from zoos is safe to use in gardens. Many zoos currently offer or sell their “zoo manure” as a means of waste management. Some zoos, such as the Woodland Park Zoo, in Seattle, have developed educational programs and marketing components based on “zoo manure.” In fact, the Woodland Park Zoo sells their composted manures as “Zoo Doo” and also has a hotline for any questions one may have regarding its use. The Zoo Doo Poopline phone number is (206)625-Poop or 7667.

Although most zoos promote their compost as being safe, there are a few precautions that one should be aware of. With any compost, one should ask the following three questions:

1. Where is it coming from?
2. What did the animals eat?
3. How will it impact my crops?

Since you have already answered the first two questions, the concerns with using the compost have to do with levels of antibiotics, pesticides, heavy metals, and other medications. Composting may take care of some of these concerns by eliminating or lowering levels, but not all. For example, composting may not bind the heavy metals cooper, zinc, and arsenic, thus preventing a reduction in levels even when the compost is finished.

It should also be noted that the finished compost from zoos may contain small rocks. This is a result from elephants that require small rocks to aid in digestion. Elephants are considered to be one of the main suppliers of zoo manure.

Please be aware that if you are considering organic certification, zoo manure that does not follow the organic rules and regulations for compost applications are not permitted.

Although the Kansas City Zoo may claim their manure as “safe” and may back up their claim with lab results, you may want to consider having the compost tested prior to applying large quantities on the land. The ATTRA publication, Alternative Soil Testing Laboratories, provides a listing of companies that test compost.