Innovative soil project offers new approach to sustainable landscaping by giving roots room to grow

Published: Sep 29, 2016

20 minutes after a rain simulator applied 2 inches of water on this highly tilled soil, from a plot that does not use a cover crop, hands remain dry as the soil is crushed by hand. The soil has no ability to hold moisture at the level of plant roots, after a short intense watering, as demonstrated, during the U.S. Department of Agriculture (USDA) Natural Resources Conservation Service soil health demonstration event “The Bundled Benefits of Soil Health” features a rain simulator that showers about two inches of water on five different soil surfaces, showing the pass through results in clear containers, on Thursday, September 18, 2014 in the People’s Garden, on the grounds of the USDA headquarters, in Washington, D.C. The trays contain soil form local farms and represent: 1. Cropland that is regularly tilled, using mechanical equipment and has no cover crop. 2. Cropland that is not tilled and uses cover crops to add organic material and manage the soil health. 3. The empty pan represents paved over soil. 4. Grassland that has been over grazed and compacted. 5. Grassland that uses managed grazing, allowing the soil and cover crop to recover. The rain simulator catches the water runoff, in clear containers to show the various levels of water that drained out of the soil and away from the root system. Results range from pavement that sheds all of the water; to grassland that uses managed grazing and retains all of the water. After the demonstration, tilled soil was dry and dusty minutes after the water was turned off. No-till soil with cover crop, shows moisture throughout and live worms still alive and burrowed in the soil that maintained its structural integrity until pulled apart. This demonstration shows some of the results of best management practices currently being used across the country. Followed this are interactive discussions about the benefits of voluntary, incentive based conservation programs to both agriculture and the environment. It also highlig (Photo by U.S. Department of Agriculture. CC by 2.0.)

Stu Schwartz, senior research scientist for the Center for Urban Environmental Research and Education (CUERE) at UMBC, has long looked with concern at the issue of soil compaction and its effect on stormwater runoff and infiltration. Impervious surfaces, such as roofs, roads, and parking lots, increase stormwater runoff and pollutants in streams and rivers. Schwartz and his students found that standard construction practices can routinely result in green permeable landscapes with compacted soil profiles that produce almost as much runoff as an impervious road or parking lot.

Looking for a better way to create sustainable, attractive landscaping, he dug into the problem of compacted soil and began collaborating with various government agencies to address these issues.

Schwartz and his students worked with the Maryland Department of Transportation State Highway Administration’s Office of Environmental Design to demonstrate and refine an alternative to standard topsoiling practices that are commonly used by contractors. The techniquesuburban subsoilingmakes the soil less compact and incorporates rich, organic compost into the soil to restore infiltration and water-holding capacity.

This practice needs little to no ongoing irrigation and fertilizer input, functions well technically, and has the markers of commercial success. It can be implemented with relatively minor changes to standard land development practices, and holds great promise as a win-win technology to reduce stormwater runoff while delivering superior sustainable landscaping.

The American Association of State Highway and Transportation Officials (AASHTO) recently identified this innovation as one of 2016’s “Sweet 16” projects. AASHTO’s “Sweet 16” distinction annually recognizes four high value projects from each geographic region of the United States.

In applying the suburban subsoiling technique, Schwartz and his students have worked with the City of Baltimore and Yorkwood Elementary School. The collaboration aims to reduce the amount of asphalt covering the ground and create construction that can allow the ground to absorb more water. Schwartz’s team developed an alternative way to restore the sustainability profile of the soil after the asphalt was removed and replaced with grass.

Photo by U.S. Department of Agriculture. CC by 2.0.


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