Post written by Hanna Bates, Program Assistant at the Iowa Water Center
Urban zones are ever expanding in Iowa with new houses, apartment complexes, and businesses emerging every year. Construction in urban zones often causes negative impacts on the soil, including compaction, which can thwart root zone growth in green spaces and may lead to erosion and water quality impairments. A new study by Logsdon et al. in the Journal of Water Resource and Protection shows that compost has the ability to improve soil and water quality in post construction sites in urban areas.
Researchers examined lawn grass plots and prairie plots that had simulated construction activities, such as driving over the plots with a tractor. This activity mimics the increase of soil compaction that occurs at construction sites due to the heavy machinery used. The plots received a treatment with three types of compost application methods: compost with aeration, rototill and compost, and surface compost. These plots were compared against bluegrass, which is a traditional lawn grass, without compost. Plots then underwent a rainfall scenario with the use of a rainfall simulator. Researchers measured numerous variables in the soil including soil water, bulk density (the degree of compaction), and morphology (the observable elements of the soil).
The study found that the use of compost lessened the bulk density in the soil (Logsdon et al 2017). High bulk density is an indicator that the soil has low absorbency for water and limits plant growth. By lowering bulk density, there is an increased ability to support healthy plant life and increase the water retained in the soil. In this study, compost additions not only provided the benefit for soil health, but it also darkened the soil more than the addition of topsoil. The study also found that when compost was combined with prairie grasses, it increased infiltration and minimized runoff and sediment loss when compared to bluegrass lawn.
If you’re a developer or even a homeowner, it may be worthwhile to consider composting and planting prairie rather than traditional lawn grass. It will not only keep your soil in place, but it will make a positive impact on the surrounding environment and lessen the stress on the public water infrastructure.
Logsdon, S.D., Sauer, P.A. and Shipitalo, M.J. (2017) Compost Improves Urban Soil and Water Quality. Journal of Water Resource and Protection, 9, 345-357. 7. https://doi.org/10.4236/jwarp.2017.94023.