AN INVESTIGATION INTO THE EFFICACY OF SMALL-SCALE COMMUNITY COMPOSTS FROM NEW YORK CITY MIXED WITH CLEAN GLACIAL SUBSOILS AS CONSTRUCTED SOIL MEDIA FOR CROP GROWTH

For decades, community composters around New York City (NYC) have been doing essential work by diverting the city's organic waste away from landfills and turning it into the "black gold" known as compost. Compost can be used as a growing medium for urban agriculture and environmental remediation. While community composting has been a longstanding practice, there is a need for more literature on how the compost produced from these sites compares to larger-scale operations. This research investigates the efficiency of compost from 6 different small-scale community sites compared to 1 mid-scale and 2 large-scale producers. Through a framework of participatory action research (PAR), we took an experimental approach comparing nutrient availability, leachate data, and the yield of kale crops grown from the composts of these 9 separate sites. In a replicated and controlled greenhouse study using composts and clean glacial subsoils from the NYC Clean Soil Bank, we found kale yield from all small-scale compost sites to be significantly higher than the yield from one local mid-sized, one local large-sized, and one non-local purchased compost (p<0.05). We also found that topdressing with compost produced slightly but not significantly higher yields than mixing compost with sediments at a 1:1 ratio. While our data shows that compost site size is an important factor in crop growth, we found that feedstock quality and ratios of inputs may be the inherent factors responsible for differences in crop yield. Analyzation of leachate data showed that top-dressed pots retained nutrients (nitrate & phosphate) for longer than mixed counterparts. Our study provides growers with quantitative data to give them insight into their compost. Ultimately, we offer this data to equip composters with more tools to carry out their indispensable labor of using compost to build resilience to the impacts of environmental degradation and climate change in New York City.