Expanded Shale as a Potting Medium Component for Bedding Plants

Nash, Mark A.; Brubaker, Tim P.; Hipp, Billy W.

doi:10.21273/hortsci.25.9.1163d

Cited by 3 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ferguson (2005) describes Expanded Shale as porous and stable aggregates, the properties which allow expanded shale to be a favorite component of plant potting media. Nash et al (1990) concluded that the growth of plants was enhanced in a medium amended with Expanded Shale and peat moss. Although the benefits of Expanded Shale on plant growth were well documented, there is lack of data in current literature on the effect of Expanded Shale on the hydraulic conductivity of fine grained soils.…”

Section: Introduction Expanded Shale As Soil Amendmentmentioning

confidence: 99%

Use of Expanded Shale Amendment to Enhance Drainage Properties of Clays

Mechleb

Gilbert

Christman

et al. 2014

Geo-Congress 2014 Technical Papers

View full text Add to dashboard Cite

Fine grained soils, in particular clays of high plasticity, are known to have very low values of hydraulic conductivity. Coarse aggregates have been used as a common fill material with fine grained soils for increasing the permeability of clayey soils. Expanded shale has recently been used as an amendment with clay soils to improve its drainage properties. However, limited effort has been made to quantify the effect of expanded shale on the hydraulic conductivity of clayey soils. Therefore, this paper presents the results of a series of laboratory fixed-wall permeameter tests conducted on naturally occurring clay deposits in the Austin, Texas area with different plasticity. The testing program comprised of clay samples with different quantities of expanded shale aggregates by volume, ranging between 0% and 50%, and compacted at two different compaction efforts (60% and 100% of the standard proctor compaction effort). The laboratory hydraulic conductivity of the amended Taylor clay compacted with 60% of the standard proctor effort increased by more than one order of magnitude with 20% expanded shale (by volume), more than two orders of magnitude with 30% expanded shale, and more than three orders of magnitude with 40% expanded shale. In addition to enhancing the drainage properties of the test specimen, the addition of expanded shale decreased the density of the clay samples which may benefit vegetation growth and root development. Another set of experiments conducted on Taylor Clay using limestone as amendment indicated similar effect on the hydraulic conductivity of the clay but led to increase in the density of the clay sample. The results discussed in this paper are being used in city of Austin to develop recommendations for increasing infiltration capacity of stormwater treatment systems by amending clayey soils with expanded shale material.

show abstract

Section: Introduction Expanded Shale As Soil Amendmentmentioning

confidence: 99%

Use of Expanded Shale Amendment to Enhance Drainage Properties of Clays

Mechleb

Gilbert

Christman

et al. 2014

Geo-Congress 2014 Technical Papers

View full text Add to dashboard Cite

show abstract

“…In the 50-PB/50-BS blend of organic materials and the traditional 75-PB/25-PM blend, maple growth was unaffected by the addition of 15% and 30% expanded shale, but was decreased by the addition of 60% expanded shale, probably due to a reduction in the quantity of plant available nutrients and water. Other researchers have observed decreased plant growth in organic-based growing media as the percentage of expanded slate or shale was increased (Carlile and Bedford, 1988;Nash et al, 1990;Rowe et al, 2006).…”

Section: Expanded Shale Content (%)mentioning

confidence: 93%

Performance of Ornamental Plants in Alternative Organic Growing Media Amended with Increasing Rates of Expanded Shale

Sloan¹,

Cabrera²,

Ampim³

et al. 2010

hortte

View full text Add to dashboard Cite

Organic and inorganic amendments are often used to improve chemical and physical properties of soils. The objective of this study was to determine how the inclusion of light-weight expanded shale in various organic matter blends would affect plant performance. Four basic blends of organic growing media were prepared using traditional or alternative organic materials: 1) 75% pine bark (PB) + 25% sphagnum peatmoss (PM), 2) 50% PB + 50% wastewater biosolids (BS), 3) 100% municipal yard waste compost (compost), and 4) 65% PB + 35% cottonseed hulls (CH). Light-weight expanded shale was then blended with each of these mixtures at rates of 0%, 15%, 30%, and 60% (v/v). Vinca (Catharanthus roseus), verbena (Verbena hybrida), and shantung maple (Acer truncatum) were planted into the growing media after they were transferred into greenhouse pots. Vinca growth was monitored for 3 months before harvesting aboveground plant tissue to determine total biomass yield and elemental composition. Verbena growth was monitored for 6 months, during which time aboveground plant tissue was harvested twice to determine total biomass yield. Additionally, aboveground vinca plant tissue was analyzed for nutrients and heavy metal concentrations. In the absence of expanded shale, verbena and shantung maple trees produced more aboveground biomass in the 50-PB/50-BS blends, whereas vinca grew more biomass in the pure compost blends. Inclusion of expanded shale in the various organic matter blends generally had a negative effect on plant growth, with the exception of shantung maple growth in the 65-PB/35-CH blend. Reduced plant growth was probably due to a lower concentration of nutrients in the growing media. Macro- and micronutrient uptake was generally reduced by addition of expanded shale to the organic growing media. Results suggest that organic materials that have been stabilized through prior decomposition, such as compost or PM, are safe and reliable growing media, but expanded shale offers few benefits to a container growing medium except in cases where additional porosity is needed.

show abstract