How an Urban Gardening Experiment could help Curb Climate Change

The plants are thriving in the gardens of Carbon Sponge at the New York Hall of Science in Queens, NY.


By Jenna Tipaldo

There’s a buzz at the New York Hall of Science in Corona, Queens, and it’s not just the bees pollinating the thriving plants of Carbon Sponge Garden. They are testing which plant varieties and soil types are able to suck the carbon out of the air and put it back into soil.” The garden seems just “beautiful and lush, and then you start to notice that there are sensors,” said Director of Public Programs Elizabeth Slagus, describing the surprise element of this unique outdoor space at the popular science museum.

With input from an interdisciplinary team of soil scientists, ecologists, city planners, programmers, designers, educators, and more, Carbon Sponge is an active science experiment.  The concept of soaking up carbon in the ground like a sponge, known as carbon sequestration, has mostly focused on rural areas. Through Carbon Sponge, designer-in-residence and project leader Brooke Singer and her team want to “jumpstart the conversation about what we can do here in city soils, which are very different from rural soils.”


Carbon sequestration is one part of Earth’s natural carbon cycle. According to NASA’s Earth Observatory, plants use the process of photosynthesis to transform carbon from the airborne greenhouse gas carbon dioxide into nutrients, some of which pass through plant roots and into the soil where microbes feed off them. “In exchange,” explained Singer, “microbes feed nutrients back to the plant in this symbiotic relationship that is the basis for life on Earth.” Essentially, the carbon becomes integrated into the soil as part of live and decaying organisms, which is “necessary for soil health and fertility.” In contrast to how fossil fuel extraction removes carbon from the ground, Singer’s project is “about how to keep it or put it back into the ground.” She said, “Nature has this ability of sequestering carbon and [the project is looking at] how can we enhance that and accelerate that rather than shooting dust into the atmosphere or some of these other kind of wild technological solutions.”

The experiment has a straightforward design: it consists of 24 hexagonal gardens containing soil from a construction site in Jamaica, Queens, obtained through the NYC Mayor’s Office of Environmental Remediation “NYC Clean Soil Bank,” a free soil exchange that matches construction sites with excess pristine soil to projects who could put it to good use. Singer’s team mixed “this 20,000-year-old pure sediment with NYC-made compost” from the NYC Department of Sanitation to create a good growing medium for the plants from materials that might otherwise end up in a landfill.

The 24 hexagons that make up Carbon Sponge are filled with a mixture of soil from construction waste and New York City compost.


The geometric gardens contain eight different conditions — each replicated three times — including an empty control condition and combinations of sunflowers, an edible mix of gooseberries and okra, and a specially developed “cover crop cocktail” from a farmer in Kansas who found that growing specific types of plants together improves productivity and fertility of the soil. Wires run from under the variety of plants (and the bare control gardens) to shoebox-sized transparent containers carrying data about temperature and moisture levels that are uploaded every hour and publicly accessible. The team also measures the amount of microbes and organic material in the soil and determines the amount of carbon sequestered. Carbon Sponge is set to wrap up the season in October and evaluate the findings after several events to engage and involve the public in this project.

Sensors are scattered among the geometric gardens of Carbon Sponge.


Through this forward-looking citizen science project, Singer wants a way to “involve people to build their own carbon sponges, whether that’s protocols or a kit and then having some sort of online, open platform for people to be contributing data and ideas and really furthering this idea of mass collaboration.” This project serves as a “platform for public engagement,” explained Singer. “Experiential projects like this that have many different facets to it allows different entry points for a wider public and we really need this conversation to be as broad and open and massive as possible.”