Topsoil Loss and Modification During Suburbanization: Implications on the Impact on Demands for Municipal Water

This study investigated the impact of soil modification due to suburbanization on municipal water demand. The tested hypothesis was that soils under natural or agricultural conditions allowed more water infiltration and storage than those disturbed by suburban development. The process of real estate development often involves topsoil removal and replacement, which impacts its quality including compaction and bulk density. This, in turn, negatively impacts water infiltration rates and soil moisture storage. Illinois has soils that are among the best in the world for agriculture, and any modification of them most likely will make them less desirable. Under suburbanized conditions, the topsoil may be removed, replaced, and compacted, thus decreasing both water infiltration and storage. Soils that have less stored soil moisture will require more irrigation to maintain a lawn, thus increasing demands on municipal water supplies. Research was conducted at two suburbanizing locations, in the region of Plainfield and of Champaign, Illinois. Plainfield is a rapidly suburbanizing area, and the research sites were converted from farmland to urban land approximately 1-6 years prior to sampling. Similarly, Champaign County research sites were converted from agriculture 2-25 years prior to sampling. We measured properties of soils on developed sites as well as on comparable sites that were in agricultural land use. Measured properties included soil fertility, water infiltration rates, bulk density, and texture. Results indicate that soil fertility was at an acceptable level at all sites. High variability in infiltration and bulk densities obscured differences in the lawn vs. the reference sites, but overall, there was no consistent impact of topsoil handling in the upper 7.6 cm where we sampled.