Arboriculture & Urban Forestry 40(6): November 2014 Arboriculture & Urban Forestry 2014. 40(6): 319–331 319 Wood Chips and Compost Improve Soil Quality and Increase Growth of Acer rubrum and Betula nigra in Compacted Urban Soil Bryant C. Scharenbroch and Gary W. Watson Abstract. Tree growth is negatively impacted by the removal of topsoil and compaction of subsoil associated with site development in urban landscapes. A research plot with 60 Acer rubrum and 60 Betula nigra was created, mimicking the typical urban landscape distur- bance. Wood-chip mulch (WC), compost (COMP), inorganic fertilizer (FERT), aerated compost tea (ACT), a commercial biological product (CBP), and a water control (NULL) were assessed for their impacts on soil quality and tree growth aſter five years. The WC treat- ment significantly decreased bulk density and increased soil moisture, organic matter, and microbial respiration. The COMP treatment increased soil moisture, organic matter, microbial respiration, pH, N, P, and K. Soil P increased with the FERT treatment. Tree growth was significantly increased with WC, COMP, and FERT treatments. No significant changes in soil properties or tree growth were observed with ACT or CBP compared to NULL; and, compared to background soil levels or other treatments (e.g., COMP and WC) ACT and CBP supply relatively minimal amounts of microbes and nutrients. This research shows strong evidence that COMP topdressings and WC mulches are effective and also cost-efficient methods for improving soil quality and stimulating tree growth in compacted urban landscape soils. Key Words. Acer rubrum; Aerated Compost Tea; Betula nigra; Compost; Inorganic Fertilizer; Organic Materials; Organic Matter; Soil; Wood-Chip Mulch. Topsoil scraping and subsoil compaction are oſten necessary to prepare sites for infrastructure. The re- moved topsoil (O and A horizons) is a substantial loss of soil organic matter (SOM) and nutrients. Compaction of the subsoil (B horizons) destroys the soil structure that is important for soil poros- ity, aeration, proper drainage, and root extension (Unger and Kasper 1994). Topsoil removal and subsoil compaction have severe negative impacts on soil quality which directly hinder the establishment and growth of urban trees. Inorganic fertilizers are oſten applied to sup- plement nutrient cycling in urban landscapes that have had the topsoil removed. A substantial body of literature has demonstrated tree growth improvements with inorganic fertilizers (e.g., van de Werken 1981; Watson 1994; Struve 2002; Percival and Barnes 2005). However, many studies also show negative effects associated with inorganic fertilizers, including: ground and surface water con- tamination (Mitsch et al. 2001; Driscoll et al. 2003; Soldat and Petrovic 2008), gaseous losses of soil carbon (C) (Khan et al. 2007; Mulvaney et al. 2009) and nitrogen (N) (Vitousek et al. 1997; Jenssen and Kongshaug 2003) and soil salt accumulation (Follett et al. 1981; Finck 1982). Furthermore, inor- ganic fertilizers have been found to impact plant resource allocation and may lead to decreases in defensive compounds and increased herbivory (Herms and Mattson 1992). The recommended annual rates for landscape tree fertilization are 1 to 3 kg N 100 m-2 yr-1 (ANSI 2004; Smiley et al. 2013). Organic materials used as mulches and amend- ments are also applied to urban landscapes to improve soil quality (Finck 1982). Chipped and tub-ground hardwood mulch and compost are two of the most highly utilized organic materials in urban landscapes. Comparatively, wood chips are coarser, have a wider C/N ratio, and decompose more slowly. Compost on the other hand, is fine tex- tured, N rich, and rapidly decomposes. Both types of organic materials have been found to positively ©2014 International Society of Arboriculture
November 2014
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
