Engineered (bioretention) media organic material properties and specifications

Engineered (bioretention) media organic material properties and specifications.
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Property	Biochar	Coir	Compost	Peat	Wood chips
Phosphorus leaching	No [1]	No to slight [2]	Yes [3]		No
Phosphorus retention	No to slight [4]	No [5]	No		No
Handling concerns	Potential explosive concerns in closed space situations; volatile compounds (depending on pyrolysis temperature) [6]	Dust [7]	None
Soil hydraulic properties	Significant improvement [8]	Significant improvement [9]	Significant improvement [10]		Improvement if incorporated [11]
Soil physical properties	Significant improvement [12]	Moderate improvement [13]	Significant improvement [14]		Improvement if incorporated [15]
Plant/microbial effects	Beneficial but varies with feedstock [16]	Beneficial [17]	Beneficial if not fresh [18]; [19]		Beneficial for fungi
Availability	Multiple distributors [20]	Widely available [21]	Widely available		Widely available
Specifications/standards available	Limited due to variability with feedstocks [22]	Yes [23]	Yes [24]		Yes for chips used for energy production [25]
Cost
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		Limited studies in stormwater applications
Applications	[26]	[27]	[28]
Chemical properties	[29]	[30]	[31]		[32]
Sustainability	Sustainable, but has current market constraints [33]	Sustainable [34]	Sustainable		Sustainable
Potential contaminants	Minor risk - metals and polycyclic aromatic hydrocarbons (PAHs) [35]	Low risk - possible chloride depending on preparation method [36]			Low risk; avoid CCA and creosote-treated sources [37]
Test methods	Not standardized but International Biochar Initiative widely used [38]	Not standardized but multiple methods available [39]	[40]; [41]
Effects of aging/Life expectancy	Varies with production method [42]	Decomposes slowly unless nutrients are added [43]	Ages relatively rapidly; aging generally benefits stormwater function by reducing nutrient loss and reducing microbial competition for nutrients [44]		Slow to moderate depending on source [45]
Notes	Characteristics vary with feedstock and pyrolysis temperature	Coir must be composted or incorporated with compost, lime, fertilizer, and/or microbes