Soil is a complex mixture of minerals, water, air and organic matter that performs many critical functions. In the United States, more than 80 percent of the population lives in cities or suburbs. While the downtown areas of cities are covered with asphalt and concrete, there are still lawns, trees, gardens, and parks. Under all this city space, even under the concrete, is soil.
Soils Support Urban Life
Before we began using pipes, drains, pumps, and other infrastructure to manage stormwater, nature provided the “green infrastructure” to slow, filter, and move water to where it belonged. In forests and wetlands, water is still managed naturally. The foundation of this network is the soil. It is the drain, the pipe, the pump, and the water treatment plant all in one.
As urban areas have grown and we’ve continued to pave over our soils, demands on both natural and manmade stormwater management systems have increased. The last few decades have brought a shift from traditional “capture, convey, and treat” drainage systems. Instead, many cities are beginning to focus on more sustainable systems to manage storm water runoff.
Often referred to as “green infrastructure”, these sustainable systems include rain gardens, living roofs, and the growing trend to plant vegetation native to the region. These practices can delay the arrival of water that reaches the sewer system and thereby reduce flooding.
The biggest benefit green infrastructure, however, is the potential reduction of pollutants entering the storm water system. Pollutants like nutrients (from fertilizers), road salt, and bacteria, can negatively affect aquatic life and public health. Green infrastructure captures these pollutants, especially those that might run off at the beginning of a storm.In both of the cities I have called home in the past few years, a few public buildings have even converted their roof tops to green space. These green roofs not only help to reduce pollutants but provide habitat for pollinators and small birds. In addition, they can provide learning spaces to learn about native plants and sustainable agricultural practices (drip irrigation, etc).
Bring it Home
The Soil Science Society of America recommends that urban dwellers consider rain gardens for their yards and compost their appropriate food wastes. Help the soil serve you by making rain gardens, making and using compost, and making an urban garden. Here are several resources and lesson plans to get you started:
- Do the Rot Thing – Download this free composting curriculum to bring the science of composting into your curriculum
- Build a Two-Can Bioreactor or small-scall indoor composting unit, or on a smaller scale consider a …
- Soda Bottle Bioreactor that will enable students to design and carry out individualized research projects, comparing variables such as reactor design, moisture content, and nutrient ratios of mixtures to be composted.
- Soil Science – Learn about basic soil science, and then explore some unique characteristics of soils found in urban areas.
- Exploration of Run-off and Infiltration – In this unit, students design and conduct experiments on runoff and infiltration, either outside or in the classroom
- Nourishing the Planet – Download the free soil science curriculum to help students realize the challenges of feeding a growing world
- Dig It! Secrets of Soil – Visit the Smithsonian exhibit’s website to access 10 online interactive learning modules
