Two case studies monitoring the soil health of aged biochar installations in Maryland's urban & roadside soils

Abstract

The application of biochar to urban and roadside soils has shown to improve stormwater runoff capture and sorb pollutants from adjacent impervious surfaces. Due to different methods of biochar production, via pyrolysis, and different feedstocks, the physical and chemical properties of produced biochar are likely to be different. Thus it’s vital for road engineers and administrators to understand and predict the effect of biochar when incorporated into to the soil. ☐ Comparing the effects of a commercial biochar with two kiln-produced biochars made from locally sourced materials (invasive plants) on soils treating stormwater runoff showed the two kiln-produced biochars had overall performance similar to that of the commercially produced biochar at the Howard Community College site: penetration resistance in the native compacted soil decreased, and infiltration rates and water retention increased. Commercial biochar showed greater improvements in soil penetration resistance and infiltration rates, with effects that were more consistent in space and over time. The variable particle size of the kiln-produced biochar was likely influential in the results. ☐ Biochar was amended to a sodic soil along an I-95 exit ramp that initially showed hydraulic improvement 5 months after biochar installation but a dramatic decrease in hydraulic function when the soil aged > 12 months. The addition of biochar had no long-term positive on penetration resistance, vegetation growth, or water infiltration. The combination of the site’s mineralogy and accumulation of sodium in the soil via runoff from road salt application over-powered any amelioration of the biochar application.