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 (Immediate Past President)
  • Maine Wastewater Control Association (former chair of the Residuals Mgt. Committee)
  • US Composting Council

Northern Tilth story on seedstock.com

List of Selected Publications

  • 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

List of Recent Presentations

2017, April Vermont Organics Recycling Summit, Randolph, VT. Nutrient Management Planning Basics for Organics: Building Soil Health While Protecting Water Quality
2016, August Low Impact Development Conference, Portland, ME.  Use of Water Treatment Residuals to Reduce the Risk of Phosphorus Run-off from Agricultural Soils
2015, October Biocycle – REFOR Conference, Boston, MA.  Digestate characterization for nutrient management planning
2015, June WEF Biosolids and Residuals Specialty Conference, Washington, D.C.  Biosolids phosphorus mangement in soils.
2015, March Maine Vegetable and Fruit School – 2015.  Biochar: myth and reality for Soil Conditioning
2014, May WEF Biosolids and Residuals Specialty Conference, Austin, TX.  Triple Bottom Line Analysis of Biosolids Management Options: Summary of TBL Modeling Results
2014, May WEF Biosolids and Residuals Specialty Conference, Austin, TX.  Maximizing Biosolids Benefits to Soils: Nutrients, Carbon and Beyond
2014, Jan US Composting Council Annual Conference, Oakland, CA.  High Carbon Wood Ash Use in Composting: A remedy for pesticide-impacted composts and nuisance odors
2013, Oct NEBRA Annual Meeting, Concord, NH.  Water Treatment Residuals Recycling: Use as a soil amendment.
2013, Sept Northwest Biosolids Management Association’s Biofest, Lake Chelan, WA. Maximizing the Benefits of Biosolids in Manufactured Topsoils.
2013, May Northern New England SWANA Annual Meeting, Exeter, ME. ecomaine: Organics Recycling Feasibility Study