Utilizing biochar to improve community tree vault soils and tree health and to reduce watershed contamination
2021, Rebecca Brianne Abney, PhD, University of Georgia (UGA) Research Foundation, Inc., Co-PI Julia Holly Campbell
The goal of this project is to investigate how the method of biochar application impacts tree growth and health in two tree species (Acer rubrum and Quercus phellos) that have yet to be investigated with the use of biochar as a soil amendment. Biochar is a frequently used soil amendment that can help improve soils that have been altered from many of these issues, particularly water imbalances, nutrient retention, and contamination. Unlike most previous studies, we will vary the concentration and application method of biochar and compare multiple tree species. We will plant seedlings of each species in soils across five treatments: soil only (control), soil + biochar mixed homogenously, soil + biochar above recommended lime dose mixed homogenously, soil + biochar below lime equivalency mixed homogenously, and soil + biochar at lime equivalency as top dressing. We will monitor soil quality and functioning post-planting along with quantifying the effects on tree growth and health. Finally, we will build a tool to calculate a recommended dose of biochar for a specific soil and tree growth outcome. We expect that our results will be useful for both professional arborists and residential homeowners managing their own trees.
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Results:
Trees along city roads and sidewalks add greenery to highly impervious cityscapes and help improve stormwater management. However, many of these trees are planted in underground plantings known as tree vaults or tree pits that are often challenging for tree growth due to drought, overwatering, heat, nutrient deficiency, drainage & aeration, and contamination. Biochar, a popular soil amendment that has high carbon content and sorbent capacity, has been shown to improve soil hydraulic conductivity, reduce contaminant concentration, and increase nutrient cation retention. Research supports the use of biochar to change soil characteristics in many management settings, yet the use of biochar in urban tree vault plantings has not been investigated. This study examined the effects of biochar applied in relation to soil volume at 1% and 5% mixed into the soil, 1% as a top dressing, and 1% at the bottom of the pot to assess effects on soil quality, water quality, and tree growth in simulated tree vaults. Two common street trees, willow oak (Quercus phellos) and red maple (Acer rubrum), were planted to monitor soil, tree, and water responses. Our results suggest that biochar increases tree growth when mixed to 5% of soil volume and applied at 1% as a top dressing. The 5% application rate had the greatest increase in soil water holding capacity and tree growth. This study concludes that different application methods should be used for different objectives as the 1% top dressing increased growth and water holding capacity.
Year: 2021
Funding Duration: 1 year
Grant Program: Tree and Soil Research Fund Grant
Grant Title: Utilizing biochar to improve community tree vault soils and tree health and to reduce watershed contamination
Researcher: Dr. Rebecca Brianne Abney
Key words:
Peer Reviewed Publications from Grant:
General Audience/Trade Publications:
Professional Presentations:
- Abney, R., Martin, A., Campbell, J., Markewitz, D., & Shelton, J. (2023). Using Biochar to Improve Soil and Stormwater Quality in Urban Tree Plantings. In Georgia Water Resources Conference. (May 2023)
- Martin, A., Campbell, J., & Abney, R. Using Biochar in Tree Vault Soils for Tree Growth and Watershed Management. In Soil Science Society of America Annual Meeting (November 2022).
TREE Fund Webinar Series – Biochar for Tree Growth and Water Quality: Exploring Potential in Urban and Disturbed Soils. December 2024
For more information on this project, contact the researcher via TREE Fund at treefund@treefund.org.