Soils and the City
Editor's note (6/14/21) : We made the revision because we felt it important for us to acknowledge the indigenous people who were here before us and to elevate a more accurate history of our region.
Soil description and sampling for lab analyses, East Meadow, Central Park. Over 100 soil profiles have been sampled and analyzed as part of the USDA-NRCS soil survey effort in NYC. Samples are collected and analyzed from each horizon, differentiated in this soil with orange nails, to at least 1 meter in depth. The profile here was to be displayed in situ for discussion as part of an international urban soils conference in September 2009. Unfortunately for the soil scientists, the site was selected for the world premier of Ken Burns’ National Parks documentary on the very same day.
Soil refers to our largely under-appreciated natural resource, a living body forming a continuum over the surface of the earth (and other planets). Visualized as a single resource much like air and water, soil properties vary gradually across the landscape, and our limited observations tend to accentuate the variability, or individual soil types. Given the extent of global environmental change resulting from human activities and our increasing worldwide urbanization, there is a new urgency in the study of anthropogenic soil attributes and effects, one of the final frontiers in soil science. Although there are similarities in urban soils globally, each city has its own unique soil pattern, affected by geography and geology, development history, land cover, land use and management. The City of New York evolved in an area of incredible natural diversity, productivity, and beauty: an assortment of islands, rivers, estuaries and bays carved out of three physiographic provinces, each with its own lithology and landscapes.
Native soil in glacial outwash, Deerfield series*, found in Staten Island Corporate Park woods along South Avenue. Native soils in NYC are commonly acid and relatively infertile, but are affected by invasives and atmospheric deposition of some pollutants and other materials. The distinctive horizons here, a result of soil forming processes, are marked by red nails. Gray colors from iron “depletion” below 60 cm indicate the presence of a seasonal highwater table. The measuring tape is in centimeters.
In Mannahatta, A Natural History on New York City, Eric Sanderson proposed over 55 ecological communities for Manhattan alone before European settlement began in the early 1600s. The Dutch forced the Lenape to either relocate out of the region or assimilate, attempting to “purchase” the land meant to be shared with its real native inhabitants. Paradoxically, New Amsterdam became a place for religious diversity at the same time. By the 1640s there were Dutch, French, Irish, Swedish, Danish, German, Belgians, Africans, Danes, as well as English dissidents seeking refuge from the Puritans in Massachusetts, who were intolerant of religious freedom. (Gotham, Burrows & Wallace, 1999.) The productive natural environment and a multi-ethnic society both served as attractions for people to arrive, but by nature of its geography, the City has had limited room for expansion. The transformation of the natural environment through extending the shoreline and filling of wetlands, much of it with waste materials, began in the late 17th century (see Gotham Unbound: The Ecological History of Greater New York by Ted Steinberg). Land re-use has been a necessity. From an earth science perspective, these activities have left the City with a significant extent of human-altered (mixed, backfilled, truncated) and human-transported (from off-site) surficial materials, often enriched in artifacts and waste products, and have determined many of the unconventional soil types of the City. Native parent materials such as glacial till and outwash, eolian (windblown), alluvial and marine deposits, as well as these human-affected materials serve as the substrate for soil formation. In addition, the anthropogenic effects of multiple land cover, land use and management types have resulted in an even broader variety of soil conditions in Gotham.
Soil formed in human-transported materials enriched in construction debris, the Laguardia series, in Soundview Park, Bronx, where a thick wedge of chunky fill was used to “reclaim” the tidal marsh. These soils are also found in inner city and residential areas. They are high in coarse fragments and human artifacts like brick and concrete, and have neutral to alkaline pH values, black carbon from ash and soot, and elevated levels of trace metals like lead. This soil is relatively young and does not display much horizonation from soil forming processes. The tape is in centimeters.
Like few other cities, New York City is fortunate to have had several surveys of its soils, conducted by the USDA- Natural Resources Conservation Service, the federal agency charged with soil mapping in the U.S. Our national soil survey program began in 1899 to help guide agricultural development when almost 40% of the U.S. population lived on farms. Now that we are a majority (80%) of urban dwellers, the program has worked hard to stay relevant to changing needs (https://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/soils/focusteams/?cid=nrcseprd1319413), although many cities still lack good soil survey information and urban soil mapping efforts can be an adventure.
Soil sealed under asphalt and pavement, East 61st Street and Madison Avenue, Manhattan. Sealed soils are essentially cut off from air, water and nutrient exchange, are generally lower in organic matter and biodiversity. Soil sealing alters the heat balance and contributes to landscape fragmentation. Tape is in inches.
Current surveys provide information on physical, chemical and mineralogical properties of the soils, along with an assessment of their productivity and hydrology, their suitabilities and limitations and potentials. Ideally an urban soil survey will help guide the best use and management of the City’s open space. In addition, survey-related research projects in New York have examined land use effects, trace metal contents, carbon stocks, microbiological communities, other characteristics of the City’s soils. Ongoing work is also examining some innovative methodology for assessing soil characteristics in the urban environment. Soil survey has provided an inventory of the incredible diversity of soil conditions in NYC: 37 native soil types (series) in glacial till (brown, red, and serpentinitic), glacial outwash, tidal marsh, eolian (wind-blown) materials, and marine sands; 29 human-altered and human-transported soil types in “clean” fill, artifact laden fill, dredge materials, solid waste landfill, and coal combustion ash. These soils differ in their color, texture, consistence, layering or horizonation, as well as their capacity to deliver various ecosystem services: biodiversity, food and fiber, stormwater management, structural support, not to mention the educational, aesthetic, spiritual experiences and inspiration. With less soil cover in urban areas (about 65% of NYC’s land surface is sealed by pavement), our soils need to work harder, and good soils information becomes even more important in working toward a better urban environment and quality of life. The
New York City Urban Soils Institute works to advance the understanding and sustainable use of our urban soils and provides a platform for cross-disciplinary communication, dissemination, and collaboration to that end.
Soil profile, East Meadow, Central Park, North Meadow series, from sampling site above. The well- formed horizons in this soil suggest that it hadn’t been disturbed in quite some time. There is not much soil organic matter due to the scarcity of vegetation and excessive foot traffic at the site. A very firm and dense substratum just below 80 cm has resulted in a “perched” water table above this zone, indicated by the presence of iron “depletions” (light gray colors).
*Soils in a series share the same parent material type, particle size class, wetness or drainage class, and general sequence of horizons. The USDA soil classification system, Soil Taxonomy, differentiates more than 20,000 soil series, predominantly in the U.S. Soil series are named for the location they were first described in. Almost half of the 66 series mapped in NYC were first identified in the City.
Soil Survey Information is available, at no charge, in several formats.
A) Detailed City-wide information can be accessed on WebSoilSurvey,
https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm
There are two options here:
1) Create a map and (pdf) report for a designated area of interest;
2) Download GIS compatible spatial and tabular data by county (borough).
B) A general or Reconnaissance Soil Survey for the City, less detailed than above, is great for students and teachers and is available as a 3’ x 3’ poster map with an accompanying manuscript at the NYCSWCD website: