A microcosm study of the common night crawler earthworm (<Emphasis Type="Italic">Lumbricus terrestris</Emphasis>) and physical,chemical and biological properties of a designed urban soil |
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Authors: | Bryant C Scharenbroch Douglas P Johnston |
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Institution: | (1) Research Department, The Morton Arboretum, 4100 Illinois Route 53, Lisle, IL 60532-1293, USA;(2) Department of Biological Sciences, University of Illinois at Chicago, 845 West Taylor Street, Chicago, IL 60607, USA |
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Abstract: | Designed soils are used in specialized urban areas, such as under sidewalks or on roof-tops. These substrates have coarse
light-weight aggregates to meet load-bearing specifications with soil in voids for rooting medium. A full-factorial microcosm
approach was used to study Lumbricus terrrestris (two adult worms added and no-worms added), compaction (bulk density of 1.95 and 1.48 g cm−3), and litter (litter and no-litter additions) in a designed soil. Earthworm biomass, soil physical, chemical, and biological
properties, anion leaching and surface C efflux was measured on days 0, 7, 14, 21, 28, 72, 112, and 140. Earthworms decreased
bulk density in compacted soil, but did not impact density of un-compacted soil. Earthworm biomass increased days 7 to 14,
but declined from days 28 to 140, likely as result of the abrasiveness of the aggregate component and relatively shallow depth
of the soil (25 cm). During the period of increasing earthworm biomass, surface C efflux, microbial biomass N, soil Ca2+ and NH4+ increased with earthworms. During the period of declining earthworm biomass, surface C efflux, microbial biomass N, soil
Ca2+ and NO3−, and leachate NO3− increased, and soil pH decreased with earthworms. While alive and dying, Lumbricus terrestris stimulated microbial activity and biomass and nutrient availability, but an apparent shift to nitrification was observed
as earthworm biomass declined. The results show Lumbricus terrestris to improve designed soil properties for plants, but the improvements may be short-lived due to the inability of these earthworms
to survive in the designed soil. |
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