|SAUER, PAT - Iowa Association Of Municipal Utilities|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/17/2012
Publication Date: N/A
Technical Abstract: Urban construction sites often have excessive erosion and compaction after topsoil removal, scraping, and grading. The purpose of this study is to determine if compaction remediation efforts are effective on a simulated urban site. The sod and topsoil were removed, the area was graded to a 1% slope, and the subsoil was compacted by trafficking. The untreated topsoil was re-applied to the control area about 5 cm deep, and compost: topsoil mixture (2:1) was surface applied to the improved area to 15 cm depth. A lawn mixture was planted to the control side (C-3 grasses). A mixture of buffalo grass (Buchloe dactyloides (Nutt.) Engelm.) and blue gamma grass (Bouteloua gracilis H.B.K.) was planted on the treatment side. Additional small trial sites compared the following treatments after topsoil removal and grading: compaction: control with only topsoil added; topsoil, plug aeration, then compost blanket; rototilled to incorporate topsoil and compost; and compost blanket. A bluegrass mixture was planted on all treatments. A Hydra probe was used to manually determine soil water content at ten spots for each treatment. Rainfall simulation was used to evaluate infiltration, runoff, and sediment loss. After three years, blocks of soils were sampled to examine roots and soil structure. The improved area held more water than the control area. Runoff was greater for the improved area than the control area, but sediment loss was reduced. In both control and improved areas, roots penetrated into the dense subsoil around clods or structural units, but the improved area showed more roots penetrating into the subsoil. All of the small sites showed reduced bulk density compared with the control, but there was no significant difference among the compost treatments. None of the treatments alleviated subsoil compaction.