Wood chips and applications of wood chips in stormwater Revision as of 20:40, 16 April 2021 by Mtrojan (talk | contribs) (→Wood chip standards and specifications)
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This page provides information on wood chips. While providing extensive information on wood chips, there is a section focused specifically on stormwater applications for wood chips.
Contents
- 1 Overview and description
- 2 Applications for wood chips in stormwater management
- 3 Properties of wood chips
- 4 Effects of wood chips on physical and chemical properties of soil and bioretention media
- 5 Standards, classification, testing, and distributors
- 6 Effects of aging
- 7 Storage, handling, and field application
- 8 Sustainability
- 9 Miscellaneous
- 10 References
Overview and description
Wood chips are small- to medium-sized pieces of wood formed by cutting or chipping larger pieces of wood such as trees, branches, logging residues, stumps, roots, and wood waste. They include bark, wood, and often leaves. Wood chips are rich in lignin, suberin, tannins. Common mulch sources include cedar, cypress, straw/hay, pine, and spruce.
In stormwater applications, wood chips are used as a mulch to provide one or more beneficial functions. Potential benefits of wood chips include but are not limited to the following. They
- decompose slowly;
- slowly release nutrients;
- effectively retain and slowly release moisture;
- moderate temperature;
- provide weed control;
- are sustainabile;
- are typically rewlatively cheap to purchase;
- resist compaction;
- create a diverse environment for soil biota; and
- may sequester some pollutants. such as nitrogen.
Physical and chemical properties of wood chips vary depending on the source, method of production, and age. Because of this variability, this page focuses on generic properties of wood chips used as mulch, except where otherwise stated.
Applications for wood chips in stormwater management
Properties of wood chips
This section includes a discussion of chemical and physical properties of wood chips, and potential contaminants in wood chips,
Chemical-physical properties of wood chips
Chemical and physical properties of wood chips
Potential contaminants in wood chips
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Effects of wood chips on physical and chemical properties of soil and bioretention media
In this section we provide information on effects of wood chips on pollutant attenuation and on physical properties of soil and engineered media.
Effects of wood chips on retention and fate of phosphorus
Effects of wood chips on retention and fate of other pollutants
Effects of wood chips on soil physical and hydraulic properties
Effects of wood chips on soil fertility, plant growth, and microbial function
Standards, classification, testing, and distributors
Wood chip standards and specifications
| Recommended values for wood chips used in a growth media (Source: see reference list in this section) | |
| pH | |
| Electrical conductivity (ms/cm) | |
| Cation exchange capacity (meq/100g) | |
| Nitrogen (%) | |
| Phosphorus (%) | |
| Potassium (%) | |
| Copper (% minimum) | |
| C:N ratio (minimum) | |
| Lignin (%) | |
| Total organic matter (% minimum) | |
| Moisture (%) | |
| Ash content (%) | |
| Impurities | |
| Fiber content | |
| Expansion | l/kg |
| Water holding capacity | l/kg |
- [1]
- recycled yard waste from public municipalities or recycled wood scraps such as pallets should be avoided due to inconsistencies in source and potential for unwanted trash or chemical additives in the mulch. To ensure you are selecting a quality mulch for your biofiltration practice, it is a good rule of thumb to ensure it has the Mulch & Soil Council Certification emblem on the bag (Figure 1). Mulch products with this certification must pass rigorous screening and are periodically audited to ensure the products meet Council standards. The certification ensures the product label is accurate and all ingredients are listed, and product claims have been verified. A Mulch & Soil Certification also ensures the mulch contains no chromated copper arsenate, which is a wood preservative found in recycled pilings, utility poles and highway structures. If mulch is not available that is certified by the Mulch & Soil Council, it should be free from waste wood material, harmful chemicals, or inorganic dyes. Mulch should not contain any fertilizer, pesticide, or other amendment. If mulch is being used in a nutrient sensitive area, a leachate analysis would ensure the mulch does not contribute to nutrient leachate from the practice.
Distributors
Test methods
Effects of aging
Prabhu and Thomas (2002) provide an extensive discussion of wood chips decomposition.
Storage, handling, and field application
Keep wood mulch away from the trunks of trees to prevent rot. If you are concerned about termites, use cedar mulch or keep other wood mulches at least 6 inches (15 cm.) from the foundation. Let your mulch age if you aren’t sure of your source. This allows time for any sprays that were used on the tree or diseases it may have had to break down.[2]
Read more at Gardening Know How: Types Of Bark Mulch: Tips For Using Wood Mulch In Gardens https://www.gardeningknowhow.com/garden-how-to/mulch/bark-mulch-in-gardens.htm
Sustainability
Miscellaneous
- [3]
- Use arborist wood chips. They absorb water and sink; bark repels water and floats and is more likely to clog inflows or overflows
- Wood chips provide more nutrition than bark, which is essentially sterile
- Wood chips discourage weed germination by tying up nitrogen at the soil surface; compost provides more nutrition for weeds to get growing