TITLE:
Comparison of Methods to Remediate Compacted Soils for Infiltration and Vegetative Establishment
AUTHORS:
Matthew A. Haynes, Richard A. McLaughlin, Joshua L. Heitman
KEYWORDS:
Compaction; Infiltration; Tillage; Root Growth; Construction Sites
JOURNAL NAME:
Open Journal of Soil Science,
Vol.3 No.5,
September
2,
2013
ABSTRACT: The process of constructing roads and buildings
usually involves the removal of topsoil and grading of the subsoil followed by
a variety of activities using heavy equipment. This presents multiple
challenges in attempts to establish vegetation on these areas: low nutrient
soils with little organic matter, high bulk densities, and low infiltration
rates. The goals of this preliminary study were to quantify the impacts of soil
compaction remediation methods on infiltration, runoff water quality, and
vegetation establishment. The objectives were to measure: 1) steady state
infiltration rate (IR); 2) quantity and quality of storm water runoff; and 3)
ground cover, biomass production, and rooting depth of vegetation during early
establishment. We evaluated four treatments: a compacted soil (C), a compacted
soil with core aeration (A), a compacted soil with deep (20 -30 cm) tillage
(DT), and a compacted soil with deep tillage and incorporated compost (CT).
Sites 1 and 2 received C, A and DT treatments and Site 3 received only DT and
CT treatments. At Site 1, runoff from natural rainfall events was collected in
plastic tubs at the bottom of each 2 × 1 m plot, and samples were measured for
volume and sediment. Infiltration rates were determined using a Cornell
Sprinkle Infiltrometer at all three sites. At Site 1, the A treatment had a
higher erosion rate during two of four rain events and higher runoff volume during
three of four rain events, when compared to C and DT. However, the aerator was
only able to penetrate 1 - 2 cm due to the compacted soil. Average event runoff
ranged from 0 to 22% (0 - 9.3 mm), 10 to 60% (1.9 -26.2 mm), and 0 to 3.5% (0 -1.1
mm) of the total rainfall for C, A, and DT, respectively. There was no
difference between C and A for vegetative biomass and IR, but both biomass and
IR were greater in the DT plots. Treatment DT had an average IR of 15 cm·hr-1,
compared to 0.16 and 0.21 cm·hr-1 for C and A, respectively. Roots
were much more abundant at the 20 -50 cm depths with DT. At Site 2, there were
no significant differences in IR, with many values too low to be measured with
the infiltrometer. Vegetative cover also did not differ between the three
treatments due to poor (16% -22% cover) grass establishment. Infiltration rates
at Site 3 were measured immediately after tillage and were 10× those at Site 2,
measured 2 months after tillage, but DT and CT values were not different. The
results suggest that deep tillage prior to seeding could maximize long-term
vegetation growth and provide areas of high infiltration to minimize
post-construction stormwater discharges, as long as vigorous vegetation can be
established quickly.