Improved or Unimproved Urban Areas Effect on Soil and Water Quality

Construction in urban areas usually results in compacted soil, which restricts plant growth and infiltration. Nutrients may be lost in storm runoff water and sediment. The purpose of this study was to determine if existing lawns benefit from aeration and surface compost additions without the negative impact of nutrient loss in runoff. Four sets of lawns were compared, with or without compost plus aeration, as a paired comparison. Surface bulk density was significantly reduced in the treated lawns (1.32 versus 1.42 Mg·m−3). Visual evaluation of soil structure showed improvement in the treated lawns. Of fifteen measurement dates over four years, four dates showed significantly higher surface soil water contents in the treated lawns compared with the untreated lawns. When compared over time, three of the four treated lawns had significantly higher soil water content than the untreated lawns. Nutrient concentrations in rainfall simulator runoff were not significantly different between treated and control lawns, which showed that compost did not negatively impact water quality. Compost and aeration helped restore soil quality for urban soils of recent construction.