Engineered (bioretention) media organic material properties and specifications
Engineered (bioretention) media organic material properties and specifications.
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| Property | Biochar | Coir | Compost | Peat1 | Wood chips |
|---|---|---|---|---|---|
| Phosphorus leaching | No [1] | No to slight [2] | Yes [3] | No [4] | No |
| Phosphorus retention | No to slight [5] | No [6] | No | Yes [7] | No |
| Handling concerns | Potential explosive concerns in closed space situations; volatile compounds (depending on pyrolysis temperature) [8] | Dust [9] | None | None | Possibly dust [10] |
| Soil hydraulic properties | Significant improvement [11] | Significant improvement [12] | Significant improvement [13] | Significant improvement | Improvement if incorporated [14] |
| Soil physical properties | Significant improvement [15] | Moderate improvement [16] | Significant improvement [17] | Significant improvement | Improvement if incorporated [18] |
| Plant/microbial effects | Beneficial but varies with feedstock [19] | Beneficial [20] | Beneficial if not fresh [21]; [22] | Beneficial | Beneficial for fungi |
| Availability | Multiple distributors [23] | Widely available [24] | Widely available | Sphagnum peat is available in Minnesota & Canada | Widely available |
| Specifications/standards available | Limited due to variability with feedstocks [25] | Yes [26] | Yes [27] | Minnesota DOT Spec 3880, United States Golf Association Green Section, OMRI, Canadian Peat Association | Yes for chips used for energy production [28] |
| Cost | Variable with distance of delivery | ||||
| Research needs | Feedstocks suitable for stormwater applications | Phosphorus fate in stormwater applications | Identifying compost-containing media mixes that do not leach phosphorus but provide other benefits | Metal/hydrocarbon/contaminant loading data by peat type | Extensive needs since there are limited studies in stormwater applications. |
| Applications | [29] | [30] | [31] | Stormwater mixes, horticultural applications, rooftop garden mixes, golf & athletic mixes | [32] |
| Chemical properties | [33] | [34] | [35] | Natural organic material | [36] |
| Sustainability | Sustainable, but has current market constraints [37] | Sustainable [38] | Sustainable | Slowly renewable, Canadian Peat Association information available | Sustainable |
| Potential contaminants | Minor risk - metals and polycyclic aromatic hydrocarbons (PAHs) [39] | Low risk - possible chloride depending on preparation method [40] | Low risk | Low risk; avoid CCA and creosote-treated sources [41] | |
| Test methods | Not standardized but International Biochar Initiative widely used [42] | Not standardized but multiple methods available [43] | [44]; [45] | Not standardized, but some methods available in ASTM4427 | [46] |
| Effects of aging/Life expectancy | Varies with production method [47] | Decomposes slowly unless nutrients are added [48] | Ages relatively rapidly; aging generally benefits stormwater function by reducing nutrient loss and reducing microbial competition for nutrients [49] | Stable | Slow to moderate depending on source and application conditions [50] |
| Notes | Characteristics vary with feedstock and pyrolysis temperature | Coir must be composted or incorporated with compost, lime, fertilizer, and/or microbes | |||
| 1We did not conduct an extensive review for peat. Sources of information include Peggy Jones (American Peat Technology, Aitkin, MN, Dr. Norm Hummel (retired), Tim White & Patrick Schoff at the Minnesota NRRI, and the Canadian Sphagnum Peat Moss Association horticultural teaching plan, Canadian Sphagnum Peat Moss Association Peat Moss and the Environment Environmental FAQ, CANADIAN PEAT HARVESTING AND THE ENVIRONMENT, SECOND EDITION, ) | |||||