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 the Canadian Peat Association | |||||