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, the Canadian Sphagnum Peat Moss Association horticultural teaching plan, Canadian Sphagnum Peat Moss Association Peat Moss and the Environment Environmental FAQ, and CANADIAN PEAT HARVESTING AND THE ENVIRONMENT, SECOND EDITION