About Northern Tilth

Andrew Carpenter opened Northern Tilth in 2003 after managing organic waste recycling projects in New England for over a decade. In 1998, Andrew received an MS in Plant, Soil and Environmental Science from the University of Maine, where his research and field work focused on the soil chemistry and soil fertility in soils manufactured from paper mill residuals and manures. For additional information, please call Andrew Carpenter at the Northern Tilth office in Belfast, Maine (207.338.5500).



  • BA in Environmental Science, 1987, Wesleyan University
  • MS in Plant, Soil & Environmental Science, 1998, University of Maine


  • Certified Crop Advisor, American Society of Agronomy
  • Technical Service Provider for Nutrient Management Plans, USDA-NRCS
  • State of Maine Certified Soil Scientist
  • Certified Nutrient Management Planning Specialist
  • University of Maine Certified Compost Specialist


  • Northeast Biosolids & Residuals Association (Treasurer)
  • Maine Water Environment Association
  • US Composting Council

Selected Publications

  • Carpenter, A and Potash, M. Use of Water Treatment Residuals to Reduce the Risk of Phosphorus Run-off from Agricultural Fields. Field Report for the VT NRCS CIG project #691644154.
  • Carpenter, A and Hanson, C.  Biosolids phosphorus management in soils: impacts to whole farm nutrient management planning and the use of water treatment residuals to decrease phosphorus risks.  Proceedings from the Water Environment Federation Biosolids and Residuals Conference.  June 2015.
  • Elenbaas, M, Beecher, N, Carpenter, A and Tarallo, S. 2014. Using the Triple Bottom Line Approach to Identify Energy Neutral Biosolids Management Options. Clear Waters, Summer 2014.
  • Connelly, S and Carpenter A. 2011. Farmland Restoration: Combining Residuals to Manufactured Topsoil . BioCycle, May 2011.
  • Brown,S.,Beecher,N.,CarpenterA. 2010. Calculator tool for determining green house gas emissions for biosolids processing and
    end use.
    Environmental Science & Technology, 44 (24), 9509-9515
  • Beecher, N., Carpenter A., and Willis, J. 2010. Estimating Greenhouse Gas Emissions from Biosolids Management. The New
    England Water Environment Association Journal, 44 (2), 22-29.
  • Kester, G.B., Brobst, R.B, Carpenter, A.F, Chaney, R.L., Rubin, A.B., Schoof, R.L., and Taylor, D.S. 2005. Risk Characterization, Assessment, and Management of Organic Pollutants in Beneficially Used Residual Products. JournalofEnvironmental Quality
  • Carpenter, Andrew. 2000. A look at the risks related to dioxin in land-applied biosolids. Water Environment & Technology
  • Carpenter, Andrew and Fernandez, Ivan. 2000. Pulp sludge as a component in manufactured topsoil. Journal of Environmental Quality
  • Carpenter, Andrew and Beecher, Ned. 1997. Wood ash finds niche in biosolids composting. BioCycle

Recent Presentations

January 2020 Maine Agricultraul Show, August, ME. Managing Agricultrual Soils with High Phosphorous Levels in Maine: Building Soil Health while Protecting Water Quality.
January 2020  US Composting Council Annual Conference, Charleston, SC.. PFAS in Compost, Residuals and Soil, And Why 2019 Seemed like the Year of PFAS.
January 2020 US Composting Council Annual Conference, Charleston, SC. Measuring Air Emissions from Composting Operations: A CCREF White Paper.
September 2018 Canadian Biosolids and Residuals Conference, Halifax, NS. Use of Water Treatment Residuals to Reduce  the Risk of Phosphorus Run-off from Agricultural Fields.
April 2017 Vermont Organics Recycling Summit, Randolph, VT. Nutrient Management Planning Basics for Organics: Building Soil Health While Protecting Water Quality
August 2016 Low Impact Development Conference, Portland, ME.  Use of Water Treatment Residuals to Reduce the Risk of Phosphorus Run-off from Agricultural Soils
October 2015 Biocycle – REFOR Conference, Boston, MA.  Digestate characterization for nutrient management planning
 June 2015 WEF Biosolids and Residuals Specialty Conference, Washington, D.C.  Biosolids phosphorus mangement in soils.
May 2015 Maine Vegetable and Fruit School – 2015.  Biochar: myth and reality for Soil Conditioning
May 2014 WEF Biosolids and Residuals Specialty Conference, Austin, TX.  Triple Bottom Line Analysis of Biosolids Management Options: Summary of TBL Modeling Results
May 2014 WEF Biosolids and Residuals Specialty Conference, Austin, TX.  Maximizing Biosolids Benefits to Soils: Nutrients, Carbon and Beyond
January 2014 US Composting Council Annual Conference, Oakland, CA.  High Carbon Wood Ash Use in Composting: A remedy for pesticide-impacted composts and nuisance odors