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Pilot study on the effectiveness of biochar based soil in improving the lifespan and health of urban trees and their carbon sequestration.


Description

Summary

As our population expands it is important that we build a society that is attentive to where and how lands develop. Deforestation accounts for 20% of CO2 emissions; the CO2 emissions from deforestation are greater than the emissions from the world’s entire transportation sector- all the cars, trucks, planes, trains, and ships combined (Friedman).

Urban trees are essential (often over-looked and under budgeted) parts of a successful urban landscape, and in the coming years they will only become more so. Tree's provide healthier and more water absorbent soil, reduce noise and air pollution, reduce energy bills, sequester carbon and provide oxygen. Green Cambridge is launching the Biochar Pilot Study to help Cambridge maximize its tree canopy to create a healthier city with a smaller carbon footprint.

Biochar is a type of charcoal made by carbonizing biomass (heating plant waste at high temperatures). It’s use in soil began centuries ago in the Amazon to increase the soil's fertility for farming. The unique properties of biochar include a high surface area which gives the ability to retain water and nutrients, a slow decomposition rate, and the ability to sequester carbon by absorbing biomass that would otherwise decompose to release greenhouse gasses. Biochar has been heavily studied in the agricultural setting but its use on street trees is still being developed (mainly in Europe).

Street trees have an average lifespan of 7 to 10 years as opposed to the 34 year lifespan of suburban trees. This is due to the conditions the trees are grown in: small soil pits with little room for their roots to expand resulting in inadequate water drainage and poor soil structure. Biochar has huge potential for urban trees, due to its richness in carbon biochar can help the soil build and maintain nutrients. By improving the soil nutrients for urban trees biochar has the ability to increase the trees life span, saving municipalities money and preserving the valued urban canopy.


What actions do you propose?

For our study we are partnering with Bruce Fulford from City Soil (distributor) and NextChar (producer) to provide us with the biochar as well as guidance on specific types of biochar and soil mixtures that would work best for our trees. We are also partnering with David Lefcourt from the Department of Public Works to organize the plantings of specific control group and biochar application trees, as well as young trees that we can potentially top dress with biochar to see a quicker response. Our pilot study will focus on about 12 trees.

To understand the effectiveness of the biochar, we will record water, growth, and environmental factors as well as perform soil tests. The soil tests will be performed prior to biochar application, and once per season subsequently. During the study we will test soil composition, pH, and carbon content of the soil. The soil composition testing will be done through a commercial lab to help us understand the heavy metals and other pollutants that are in the soil and affecting the tree. Soil pH readings will be measured by Green Cambridge staff with a test kit and will help determine the health of the soil and its micro-organisms. For the carbon measurements we are partnering with Doctor Andrew Reinmann from Boston University to help us read the quality of carbon sequestration the soil is providing.

The data collection for this study would be conducted by Green Cambridge in partnership with DPW staff for a minimum of five years. The data and tests will be clearly outlined and recorded in a shared google spreadsheet created by Green Cambridge. Green Cambridge will monitor and document the trees’ growth and health status throughout the project, with assistance from DPW. DPW will do the initial planting and biochar application as well as the watering with gator bags per standard protocol. The data from this project will be compiled in an interim progress report and final report by Green Cambridge to be provided to the city and public.


Who will take these actions?

  1. Selection of trees - Cambridge DPW
  2. Biochar procurement - DPW will pick up biochar from City Soil (distributor), NextChar (provider) to deliver biochar to City Soil
  3. Soil measurements - Green Cambridge, Commercial lab, BU
  4. Biochar application and tree planting - DPW with City Soil help (Bruce Fulford at City Soil will help provide soil mixture instructions)
  5. Tree watering - DPW with pre-measured gator bags
  6. Tree measurements and observation - Green Cambridge and Cambridge Tree Warden (once per season)
  7. Interim Report documenting tree survival, growth, soil changes, other observations - Green Cambridge with DPW sign-off
  8. Final Report and recommendations on use of biochar by city - Green Cambridge with DPW sign-off


Where will these actions be taken?

Cambridge, MA


How much will emissions be reduced or sequestered vs. business as usual levels?

Urban trees provide economic, environmental, and health benefits that improve the overall energy use and pollution levels of a city. Urban trees help offset climate change by capturing CO2, reducing building energy use, and reducing CO2 emissions from power plants and water treatment plants due to there ability to preserve ground water and lower temperatures.

On average, one tree living for forty years can sequester 1 ton of CO2. A study on city trees by MillionTrees NYC showed that New York City’s trees store about 1.35 million tons of carbon valued at $24.9 million. In addition, the cities trees remove over 42,000 tons of carbon each year. By using trees to modify temperatures, the amount of fossil fuels used for cooling and heating by homeowners and businesses was also reduced, saving the city $27 million annually.

This study shows how much healthy urban trees can effect the emissions and environmental health of a city landscape, such as Cambridge.

 


What are other key benefits?

Urban landscapes are taking over more and more of our global land each year. A focus on sustainable development to meet both human developmental needs, as well as to sustain the natural systems upon which we depend, is more urgent than ever. Using biochar as a soil amendment in often nutrient and structure deprived urban soil has the potential to grow more resilient trees and plants that can sequester carbon and contribute to creating a home for natural cycles within our cities. 


What are the proposal’s costs?

Items and Costs for Biochar Pilot Study

  • Trees (12-15) = Free, using already purchased DPW city trees
  • pH test kit = $30
  • Biochar (From NextChar) = Free, NextChar is donating for Pilot
  • Carbon Soil measurements = Free, BU Doctor Andrew Reinmann is donating time and soil testing instrument
  • Soil Measurements (UMass Amherst Soil Lab) = $1,800 over 5 years, testing twice a year. (12 samples. $15 per sample. $180 per season)
  • Staff Time Green Cambridge = $500

 

Total Anticipated Costs (to Green Cambridge): $2,330 


Time line

This is a short-term pilot study with the goal of providing positive results to the city that will create long term changes in how the city cares for its trees. We hope the use of biochar on city trees and plants will have a long-term impact on the environmental health and carbon footprint of Cambridge and cities like it.

Year 1

  1. Selection of biochar and control group trees for study by Green Cambridge and DPW
  2. Biochar procurement - NextChar provides to City Soil where DPW picks it up
  3. Initial baseline soil measurements by Green Cambridge, commercial lab, and BU
  4. Biochar application and tree planting by the DPW with City Soil help (Bruce Fulford at City Soil will help provide soil mixture instructions)
  5. Seasonal soil measurements by Green Cambridge, Commercial lab, and BU
  6. Tree watering by DPW per standard protocol with gator bags

 

Year 2

  1. Seasonal soil measurements by Green Cambridge, Commercial lab, and BU
  2. Tree measurements and observation by Green Cambridge and Cambridge Tree Warden once per year
  3. Tree watering by the DPW per standard protocal with gator bags

 

Year 3

  1. Seasonal soil measurements byGreen Cambridge, Commercial lab, and BU
  2. Tree measurements and observation by Green Cambridge and Cambridge Tree Warden once per year
  3. Interim report documenting tree survival, growth, soil changes, and other observations byGreen Cambridge with DPW sign-off

 

Year 4

  1. Seasonal soil measurements by Green Cambridge, Commercial lab, and BU
  2. Tree measurements and observation by Green Cambridge and Cambridge Tree Warden once per year

 

Year 5

  1. Seasonal soil measurements byGreen Cambridge, Commercial lab, and BU
  2. Tree measurements and observation by Green Cambridge and Cambridge Tree Warden once per year
  3. Final Report and recommendation to the city by Green Cambridge with DPW sign-off

 


Related proposals


References

Scharenbroch, B.C., E. Meza, M. Catania, and K. Fite. 2013. Biochar and biosolids increase tree growth and improve soil quality for urban landscapes. Journal of Environmental Quality. doi:10.2134/jeq2013.04.0124.

Lara A. Roman, John J. Battles and Joe R. McBride, “The balance of planting and mortality in a street tree population,” Urban Ecosystems

Scharenbroch, B.C., E. Meza, M. Catania, and K. Fite. 2013. Biochar and biosolids increase tree growth and improve soil quality for urban landscapes. Journal of Environmental Quality. doi:10.2134/jeq2013.04.0124

Thomas L. Friedman. P Farrar, Straus and Giroux. 2008, print. Hot, Flat, and Crowded: Why We Need a Green Revolution--and How It Can Renew America

http://www.milliontreesnyc.org/html/urban_forest/urban_forest_benefits.shtml