Difference between revisions of "Mulch"

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[[File:Wood chip mulch.jpg|thumb|Pine mulch will help hold moisture in the soil]]
[[File:Wood chip mulch.jpg|thumb|Pine mulch will help hold moisture in the soil]]
*Mulch is considered to be an normal finishing touch to many types of formal landscaping. Maintaining mulch application can help increase aesthetic value of LID BMPs.
*As in other landscaping applications, the mulch helps to preserve soil moisture for plant survival, and suppresses weed growth.
*Mulch can also help to maintain the organic matter content of underlying filter media, which provides cation exchange capacity for pollutant removal.
*Regular fresh applications of wood mulch can also promote denitrification, reducing nitrates in impacted surface waters.
*Mulch should be applied on the surface of the BMP in a layer of 75 -100 mm.
*Double-shredded hardwood or softwood mulch is recommended for LID facilities. Its fibrous texture knits together somewhat; providing limited erosion control.
*In areas with particularly high flow (e.g. around [[inlets]] and [[forebays]]) coarse decorative aggregate or [[stone]] is recommended to better dissipate energy and protect it from erosion.
*This advice also holds for [[stormwater planters]], which often experience concentrated flow from a [[downspout disconnection| roof downspout or drain]]. 
*All organic mulches have the potential to float and migrate in surface flow, particularly after a previously dry period. <ref> Simcock, R and Dando, J. 2013. Mulch specification for stormwater bioretention devices. Prepared by Landcare Research New Zealand Ltd for Auckland Council. Auckland Council technical report, TR2013/056 </ref>


In addition to its aesthetic qualities, mulch is an essential functional component of many LID practices. Mulch assists in educing soil erosion, retaining moisture for the plant material, moderating soil
temperature, preventing surface sealing and reducing colonization by opportunistic weed species. Wood mulch allows for cation exchange in the upper organic layer of the soil, capturing heavy metals. Regular fresh applications of wood mulch also promotes denitrification, reducing nitrates in impacted surface waters.
Mulch should be applied on the surface of bioretention practices at a minimum depth of 75 mm and added to cover bare areas in order to avoid erosion. Mulch should only be removed and replaced when contamination has become a concern, when clogging has occurred, or when surface storage volume has been reduced.
Avoid the use of [[Stone|stone]] as a cover for vegetated practices. While stone is a low
maintenance surface treatment, it hinders the addition of plant matter and formation of
topsoil and does not provide the same treatment benefits as mulch. Also,
the stone can be problematic for maintenance if it migrates into the soil.
The use of landscape fabric is a common method of reducing weed species in many
landscapes. However, because landscape fabric is likely to become clogged with
sediment in an LID facility, it is not recommended.
Shredded hardwood mulch is generally recommended for LID facilities. Its fibrous texture knits together somewhat; providing limited erosion control. In areas with particularly high flow (e.g. around inlets) inorganic mulch or coarse decorative aggregate is recommended instead, as these will not float. All organic mulches have the potential to float and migrate in surface flow after a previously dry period. <ref> Simcock, R and Dando, J. 2013. Mulch specification for stormwater bioretention devices. Prepared by Landcare Research New Zealand Ltd for Auckland Council. Auckland Council technical report, TR2013/056 </ref>
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[[Category:Materials]]
[[Category:Materials]]
[[Category:Green infrastructure]]
[[Category:Green infrastructure]]

Latest revision as of 15:01, 15 July 2020

Pine mulch will help hold moisture in the soil
  • Mulch is considered to be an normal finishing touch to many types of formal landscaping. Maintaining mulch application can help increase aesthetic value of LID BMPs.
  • As in other landscaping applications, the mulch helps to preserve soil moisture for plant survival, and suppresses weed growth.
  • Mulch can also help to maintain the organic matter content of underlying filter media, which provides cation exchange capacity for pollutant removal.
  • Regular fresh applications of wood mulch can also promote denitrification, reducing nitrates in impacted surface waters.
  • Mulch should be applied on the surface of the BMP in a layer of 75 -100 mm.
  • Double-shredded hardwood or softwood mulch is recommended for LID facilities. Its fibrous texture knits together somewhat; providing limited erosion control.
  • In areas with particularly high flow (e.g. around inlets and forebays) coarse decorative aggregate or stone is recommended to better dissipate energy and protect it from erosion.
  • This advice also holds for stormwater planters, which often experience concentrated flow from a roof downspout or drain.
  • All organic mulches have the potential to float and migrate in surface flow, particularly after a previously dry period. [1]
  1. ↑ Simcock, R and Dando, J. 2013. Mulch specification for stormwater bioretention devices. Prepared by Landcare Research New Zealand Ltd for Auckland Council. Auckland Council technical report, TR2013/056

a top dressing over vegetation beds that provides suppresses weeds and helps retain soil moisture in bioretention cells, stormwater planters and dry swales.

a top dressing over vegetation beds that provides suppresses weeds and helps retain soil moisture in bioretention cells, stormwater planters and dry swales.

Low Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting.

The engineered soil component of bioretention cell or dry swale designs, typically with a high rate of infiltration and designed to retain contaminants through filtration and adsorption to particles.

Best management practice. State of the art methods or techniques used to manage the quantity and improve the quality of wet weather flow. BMPs include: source, conveyance and end-of-pipe controls.

Includes the protection of soil from dislocation by water, wind or other agents.

A broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations.

(1) The wearing away of the land surface by moving water, wind, ice or other geological agents, including such processes as gravitation creep; (2) Detachment and movement of soil or rock fragments by water, wind, ice or gravity (i.e. Accelerated, geological, gully, natural, rill, sheet, splash, or impact, etc).

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

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