Feb. 16, 2016 – Virginia Tech researchers have developed a soil rehabilitation method that can help fix the compacted, rock-hard soils left behind after land development and building construction.
Trees planted in rehabilitated soil have as much as 84 percent greater canopy than those in untreated soil, according to Susan Day, associate professor of urban forestry in the Department of Forest Resources and Environmental Conservation in the College of Natural Resources and Environment The research by Day and colleagues appears online ahead of print in Urban Forestry & Urban Greening.
Past work showed that their method, named “Soil Profile Rebuilding,” decreases soil compaction, increases carbon sequestration, and increases the rate at which water moves through the soil, thereby improving storm-water capture.
“City soils are much maligned, and with good reason,” said Day, who has a joint appointment in horticulture in the College of Agriculture and Life Sciences. “City soils are stripped and compacted and mixed and layered until they have little in common with their less-disturbed cousins in agricultural and forested lands.”
The Soil Profile Rebuilding method uses compost and a special subsoiling technique adapted for tight urban spaces to create pathways through the soil for root and water penetration. A backhoe with a tined bucket is used to break up the compacted soil and incorporate compost to a depth of two feet. Then four inches of topsoil are applied and rototilled to a depth of six to eight inches, followed by planting trees or shrubs whose roots help the soil continue to develop.
Unlike many previous approaches to alleviating soil compaction, the effects of Soil Profile Rebuilding persist “because the technique doesn’t just break up the soil physically; it also affects biological activity in the soil,” Day explained. It is a useful tool for designers seeking SITES® (Sustainable Sites Initiative) accreditation from the U.S. Green Building Council.
The rehabilitation process was developed by Day, faculty colleagues, and graduate students in both colleges over the course of seven years of research at Virginia Tech and in Arlington County, Virginia, in partnership with Vincent Verweij, Arlington County’s urban forester. (continue reading original story...........)