Over the last century, pavement has proliferated globally resulting in more than 43,000 square miles of paved surfaces in the United States–roughly the size of Ohio. Impervious surfaces lead to increased flooding, heat island effect and reduced soil function. Because of the centralized nature of pavement management and its perceived utility, almost no research has been conducted on how to intentionally disrupt the pavement with plants and “unseal” the soils beneath them.
Both art installation and ecological study, Pavement|Fractured proposes a response to flooding and heating through developing a process for fracturing pavement where we strategically plant cover crops to grow in an aesthetically intentional pattern, which will eventually increase water drainage and greening of the landscape, reduce temperatures and improve soil ecosystem function.
A site was established on asphalt at the low end of a sloped parking lot. Holes were drilled to mimic natural fractures ranging from 0.7cm to 20 cm and filled with potting soil and seeds of tillage radish. Plots were monitored for seedling survival and plant size and samples removed after 60 days to measure root length and penetration. Subsoil was removed from 20 cm holes before and after planting to assess changes in soil respiration and function.
Results/Conclusions
By using a combination of drilling and potting media, it is possible to establish tillage radish in a paved surface. Seedling survival in 20cm drilled treatments was 80%, compared to 71% for 5cm drilled treatment 52% for 2.5 cm and 5% for 0.7 cm drilled treatment. However, root proliferation in the 2.5 and 5 cm drilled treatments was almost entirely confined to the potting medium in the planting hole, while the plants in the 0.7cm hole were rooted in pavement cracks. Plants in 20 cm drilled treatments exhibited long tap roots that extended at least 30cm into the soil, exploiting the subsoil for water and nutrients.
Continued research includes assessing the ability of tillage radish to fracture asphalt given a longer growth cycle, and the effect of asphalt planting on surface temperature, water infiltration and soil function, as well as other, chemical means of weakening asphalt and encourage patterned fracturing. While ecologists have long understood the detrimental effects of pavement, collaborations between art and science may prove more effective at altering public perceptions and finding democratic solutions to addressing the vast spaces of existing pavement than science alone.