CARBON STORAGE BY URBAN SOILS UNDER DIFFERENT LAND USE AND MANAGEMENT AT SNUG HARBOR CULTURAL CENTER & BOTANICAL GARDENS, NEW YORK CITY

Soil is one of the largest reservoirs of organic carbon on Earth. Soil organic carbon is sensitive to land use and how the soil is managed. Gradual conversion of grasslands and forests into agricultural lands has been occurring over the past several centuries and has resulted in significant loss of soil carbon stocks around the world. The goal of this study is to understand and quantify carbon stocks in urban soils and how different land use and management affects the retention of carbon in soils. Three sites were chosen at the Snug Harbor Cultural Center & Botanical Gardens in New York City, where there is a 2.5-acre production farm and a small urban forest. Soil pits were dug at three research sites, soil profiles were described in the field, and soil samples were collected by pedogenic horizon to a 1-meter depth. All three soils were formed in glacial till primarily from red sedimentary rocks, and all fit the Cheshire soil series. Soil samples were analyzed in the laboratory for total soil organic carbon and black carbon, as well as additional physical, chemical, and biological properties. Soil organic carbon stocks (SOC) varied among land use and management. Soil organic carbon (SOC) density to 1 meter in the Heritage Farm is 26.1 kg/m², compared to 19.6 kg/m² in the woodland and 17.6 kg/m² for the hedgerow site. The SOC at Heritage farm (26.1 kg/m²) is 3-4 times higher than some average values for agricultural lands in the North-East US (6 kg/m²) and New Jersey (6.98 kg/m²). This can be attributed to the sustainable practices at the urban farm, such as using of compost, crop rotation, low-tilling cultivation, and the incorporation of cover crops. Invasive earthworms are pervasive in the woodland at Snug Harbor, thus likely lowered the carbon stocks in such an urban forest. Therefore, urban agricultural soil can have higher levels of carbon storage than forest soils when under sustainable management. Retention of carbon in soils can help mitigate climate change and provide sustainable food security, especially in urban areas.