Impact of Residential Prairie Gardens on the Physical Properties of Urban Soil in Madison, Wisconsin

Abstract

Prairie gardens have become a common addition to residential communities in the midwestern United States because prairie vegetation is native to the region, requires fewer resources to maintain than turfgrass, and has been promoted to help remediate urban soil. Although prairie systems typically have deeper and more diverse root systems than traditional turfgrass, no one has tested the effect of this vegetation type on the physical properties of urban soil. We hypothesized that residential prairie gardens would yield lower soil bulk density (BD), lower penetration resistance (PR), greater soil organic matter (SOM), and greater saturated hydraulic conductivity () compared with turfgrass lawns. To test this hypothesis, we examined 12 residential properties in Madison, WI, where homeowners had established a prairie garden within their turfgrass lawn. Despite a consistent trend in the difference between vegetation types, no significant main effects were found (i.e., a difference between vegetation types when averaged over depth) for any of the four soil properties measured in this study. Differences were found with depth and depended on a significant interaction with vegetation type. At the surface depth (0-0.15 m), soil beneath prairie gardens had 10% lower mean BD, 15% lower mean PR, 25% greater level of SOM, and 33% greater compared with soil beneath the adjacent lawns. These differences were not detected at deeper sampling intervals of 0.15 to 0.30 m and 0.30 to 0.45 m. Although not statistically significant, the consistent trend and direction among soil variables suggest that residential prairie gardens had changed the surface soil at a rate that marginally outpaced turfgrass and calls for controlled experiments to identify the mechanisms that might enhance these trends.

Current and historical land use influence soil‐based ecosystem services in an urban landscape

“…Recovery from physical disturbance associated with construction may also play a role, with faster vegetation-driven recovery of surface soils compared to deeper soils (Fig. 3C,D; Golubiewski 2006, Johnston et al 2016.…”

Aboveground traits define differences in biomass allocation among 16 prairie species

“…We posit that plant traits could inform plant selection toward desirable outcomes. For example, forb species with both a rosette morphology and a late phenology (e.g., O. ohioense , a goldenrod) might be selected to optimize root biomass in residential settings where forbs are favored over C 4 grasses because of the grasses’ competitive growth (Johnston, 2006). Data on root turnover would also complement the use of the groupings to predict root biomass.…”

“…Native C 4 grasses can invest as much as 80% of their total biomass to belowground structures (Rice et al., 1998), which in turn alters the arrangement of soil solids and pores to stabilize soil aggregates (Jastrow, Miller, & Lussenhop, 1998), build soil structure (Baer & Blair, 2008), and improve soil–water flow (Udawatta, Anderson, Gantzer, & Garrett, 2008). By inference, prairie plants have the potential to bring desirable attributes to urban plantings intended for stormwater management (Johnston, Balster, & Zhu, 2016). There are also lots of options when it comes to plant species selection.…”

Soil in the City: Sustainably Improving Urban Soils

“…They hypothesized that residential prairie gardens would have better soil physical properties compared with turfgrass lawn and that well‐structured soil under prairie gardens would therefore promote infiltration and mitigate stormwater runoff. Johnston et al (2016) tested these effects comparing soil physical properties under paired prairie gardens and turfgrass lawn by taking advantage of a “natural” experiment in which homeowners introduced prairie gardens into typical residential landscapes in Madison, WI. Results showed the surface soil beneath prairie vegetation had 10% lower bulk density, 15% lower penetration resistance, 25% greater soil organic matter, and 33% greater saturated hydraulic conductivity compared with the adjacent lawns.…”

“…As Johnston et al (2016) note, restoration of tallgrass prairie biome once dominant in the midwestern United States may help in ecologically engineering urban soils to improve their functioning. They hypothesized that residential prairie gardens would have better soil physical properties compared with turfgrass lawn and that well-structured soil under prairie gardens would therefore promote infiltration and mitigate stormwater runoff.…”