Biochar from Biosolids and Source Separated Human Urine: Soil Health Impacts and Farmer Perspectives

Project Overview

Project Type: Research Only
Funds awarded in 2022: $175,724.00
Projected End Date: 11/28/2025
Grant Recipient: Rich Earth Institute
Region: Northeast
State: Vermont
Project Leader:
Abraham Noe-Hays
Rich Earth Institute


  • Agronomic: corn


  • Crop Production: application rate management, fertilizers, nutrient cycling, nutrient management
  • Education and Training: demonstration, on-farm/ranch research, participatory research
  • Natural Resources/Environment: carbon sequestration
  • Production Systems: holistic management
  • Soil Management: nutrient mineralization, organic matter, soil analysis, soil quality/health
  • Sustainable Communities: local and regional food systems, sustainability measures

    Proposal abstract:

    This research will investigate a novel approach to meeting the identified farmer needs of reducing energy-intensive agricultural inputs, participating in sustainable nutrient cycling, and promoting soil health. Our approach aims to accomplish these goals through the reclamation of human waste as fertilizer, in the form of biosolids-derived biochar and source separated human urine. Producing biochar from biosolids offers an opportunity to convert a waste into a value-added product that can increase soil organic matter in soils, help mitigate climate change, and improve crop production, while reducing the need for additional external inputs. The benefits of biochar are known to be enhanced further when biochar has been charged/incolulated/blended with nutrient rich materials before use, such as urine-derived fertilizer. Thus, using both the solid and liquid human waste products could be a way to reduce the need for external synthetic fertilizers and use both forms of waste simultaneously.

    Our project will evaluate the potential for adoption of these novel human waste-derived soil amendments through a 3-year field experiment measuring the effect of these amendments on soil health, and through social research on farmer attitudes and perceptions.

    The field experiment, using corn, will examine how combinations of source-separated human urine, biomass biochar, and biosolids biochar affect soil health, crop yield, and nutrient leaching, compared to currently-used conventional and organic amendments. We will use the following nine treatments: Control (no amendments); Urea; Urine; Compost; Compost + urine; Biomass biochar + urine; Biosolids biochar + urine; Biosolids biochar + urine (with annual reduced-rate biochar application); and Compost + biosolids biochar + urine.

    The social research component builds on our previous SARE projects, which documented strong farmer interest in and adoption of source-separated human urine as fertilizer. However, we also identified concerns about urine related to potential soil health effects from residual pharmaceuticals, and concerns about biosolids related to microcontaminants, organic pollutants, and heavy metals. The use of biosolids biochar combined with urine may allay these farmer concerns, because the high-temperature conversion of biosolids to biochar eliminates many organic contaminants and immobilizes heavy metals. Furthermore biochar has been shown to immobilize organic contaminants, such as the residual pharmaceuticals in urine. Our goal will be to understand farmer perceptions of biosolids biochar, a novel amendment, and determine what further research or best practices may be required for this product to be adopted by farmers in the Northeast. Social research will include 20 farmer interviews, a regional survey, and farm field days. 

    Project objectives from proposal:

    This research will investigate opportunities to meet identified farmer needs to reduce energy-intensive agricultural inputs, participate in sustainable nutrient cycling, and promote soil health, through the reclamation of human waste as fertilizer in the form of biosolids-based biochar and source separated human urine. We will investigate their soil health effects in comparison to conventional and organic amendments, including wood-derived biochar. We will conduct social research with farmers to understand their perceptions of biosolids biochar, a novel amendment, and determine what further research or best practices may be required for this product to be adopted by farmers in the Northeast.




    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.