New York City's Department of Sanitation (NYCDOS) has completed a one-year study of the diversion potential of backyard composting. Not surprisingly, the study found that backyard composting appeals only to a small percentage of New Yorkers who are avid gardeners or who have yards.
By combining survey research, waste composition analysis and cost-benefit calculations, the NYCDOS also concluded that backyard composting is not likely to have a measurable effect on New York's waste diversion. However, backyard composting still is a great way of promoting waste awareness among city residents, according to the NYCDOS
Targeting suburban neighborhoods of New York City in which there are predominately one- or two-family homes with backyards, the NYCDOS contracted with the city's four botanical gardens for assistance in recruiting composters. Promotions included letters, telephone calls and door-to-door visits. Gardens staffers offered residents a compost bin, a scrap bucket, literature and follow-up training - for a total cost of $10 dollars.
Those who agreed to compost were encouraged to begin immediately, but they were not informed of the NYCDOS's waste composition study. In the meantime, before and after the recruitment period, curbside waste was collected from a random sample and analyzed to determine its composition, including food waste, yard waste, recyclables and other materials. The city sampled both composters and noncomposters. A third group's waste - from a suburb unexposed to the city's promotional efforts - was sampled to eliminate the potential effect of those promotions on their waste stream. Simultaneously, telephone surveys and focus groups gathered residents' reasons for declining or deciding to compost, as well as their attitudes toward recycling, the environment and the outdoors.
Despite the intense outreach effort, only 9.4 percent of households with backyards elected to compost. Avid gardeners who worked in their yards and could use the compost recognized the benefits to composting. Others - even those considered environmentally friendly - however, couldn't imagine composting because it did not directly benefit them.
Waste composition data showed, on average, that each composting household left 2.5 fewer pounds of food waste per week at the curbside than non-composting homes. NYDOS could not accurately assess the yard-waste composting rate, however, because yard waste measurements fluctuated significantly from household to household.
During the study, recycling increased in the test neighborhoods by approximately 3.5 pounds per week. This possibly was due to program outreach as well as the visibility of the sanitation staff during waste collection, which would not be repeated in future citywide composting programs.
An estimated 930,000 homes in New York City have outdoor space where a compost bin could be placed. Using the sample's 9.4 percent of homeowners volunteering to compost, the city estimates a maximum potential of 87,000 households could compost. Multiplied by 2.5 pounds per week, these households would annually divert approximately 5,700 tons per year - a mere 0.15 percent of the 3.7 million tons the city annually generates. If yard waste were composted, the composting rate would be about 5 pounds per week, but this only would increase the diversion from 0.15 percent to 0.30 percent.
Thus, NYCDOS concluded that backyard composting is not a reliable or substantial waste reduction method, although promoting it has benefits.
Research found that almost all composting volunteers said the program was informative, rewarding and well-run. Focus groups revealed that the program encouraged citizens to think more about their waste - an outcome that NYDOS values in its ongoing efforts to educate communities about waste prevention, reuse and recycling.
Moreover, after the research segment of the study concluded, the botanical gardens tried several different outreach and bin distribution strategies to continue promoting composting.
Cost benefit comparisons showed that the benefits of the program in which the gardens wholesaled bins to residents at one-day special events were cost-effective. Consequently, the NYCDOS will continue to promote the program in the future.
Finally, the study broke new ground in composting research. While many cities use surveys to determine who is composting, they generally rely on residents' own estimates of how much is placed in the bin.
Robert Lange, NYCDOS' Bureau of Waste Prevention, Reuse and Recycling Director, states that among backyard composting evaluations, this study was the first to directly measure changes in a household's waste composition. The program also was the first to use non-composting households as a comparison group so that other factors affecting waste composition could be eliminated.
"New York is densely populated and we have fewer backyards and gardens," Lange states. "With our substantial waste stream, we felt it was especially important to take a realistic look at how much diversion we could expect from New York-style backyard composting. We feel very confident about the results we've achieved."
To obtain "Backyard Composting in New York City: A Comprehensive Program Evaluation," visit www.ci.nyc.us/ strongest or call Robert Lange at (212) 837-8156.