Former NYC Compost Project hosted by Big Reuse Project Manager, Gina Baldwin, gives us a rundown of the path your food scraps take from when you drop them off to when the finished compost they become improves soils around the city.
Making great compost takes a lot of hands in NYC. Each week, thousands of New Yorkers visit NYC Compost Project food scrap drop-off sites, bringing with them bags and boxes of organic materials they have carefully separated in kitchens from Forest Hills to Greenpoint. At food scrap drop-off sites, residents empty containers of frozen food scraps into big green bins, but where do they go at the end of the day? Dropping off food scraps is the just first step in making great soil for NYC.
On an average day, NYC Compost Project staff load the green food scrap bins on our truck and take them to our compost site in Long Island City underneath the Queensboro Bridge. We work at the site every day of the week to ensure the best possible conditions for our decomposers, our neighbors, our staff, and volunteers. Over the years we have grown from using solely hand tools, to using several hi-tech tools to help us (and our backs) make compost for NYC soils.
Commuter Composting at Vernon Jackson 7 Train in Long Island City.
Food scrap drop-off at Forest Hills Greenmarket.
Aerial view of our compost site at Queensbridge Baby Park.
Once the food scraps are at the site, we mix them with leaves and woodchip from NYC Parks, residential leaves collected at our drop-off sites, and sawdust from our colleagues at the BIG!Millworks program. We combine all of the ingredients into our mixer to evenly distribute wet, nitrogenous (nitrogen-rich) and dry carbonaceous (carbon-rich) materials. After mixing for several minutes, the raw materials are ready to either start a new pile, or be incorporated into an already working pile.
Emptying food scraps in the mixer.
Mixing scraps, leaves and wood chip.
Cuyler wheeling out the food scraps.
With our skid steer (lovingly named Tilly) we move the material into a windrow – a long, tall compost pile. Depending on the day, the windrow may be put onto an Aerated Static Pile system. The ASP system uses forced air from a blower to push air into the pile at intervals which aids the decomposition process. Air is a necessary component to the aerobic composting process, and prevents anaerobic bacterial activity which can produce methane gas. We then cover the heap with about 12 inches of finished compost which acts as a biofilter – a living filter to process odor compounds. In this case, we’re also using the biofilter to insulate the pile as well as making sure all food scraps are tucked completely in the mix. In the first week, internal temperatures will reach upwards of 160 degrees. This heat is created by the organisms working to decompose the organic materials. Because of the high temperatures, most activity is conducted by bacteria, fungi and other microorganisms. Larger decomposers such as worms cannot survive at these high temperatures but are often found in backyard and community garden compost bins.
Building a compost window.
Microbes in compost generate heat.
The material takes about three months to completely break down using this process. One of the easiest ways to tell if compost is finished is by smelling it. The compost should smell earthy and there should be no recognizable food waste materials present. There will be woody material in the pile. This can be sifted out and added to the next compost pile, creating a jump-start of activity due to the bacteria present on the wood chips. The “bag test” is another way to determine if compost is ready to use. Put a handful of compost in a sealable plastic bag. After a few days, open the bag up and smell the compost. If it smells like ammonia, it’s not ready as microbes are still working. If it smells like earth, it’s ready to use!
All of our compost goes to community and school gardens, farms, and tree stewards to grow healthy food and create beautiful green spaces across NYC.
Street trees in Brooklyn
Astoria Park Butterfly Garden
Riis Community Garden in Queens