Past Research Projects

Compost Use in Post-Construction Stormwater Practices: A Systematic Review & Results from Listening Sessions

The Compost Research and Education Foundation (CREF) and the University of Minnesota (U of M) embarked on research to better understand the best uses of compost in stormwater bioretention media and identify compost characteristics that are most impactful to the success of these systems. It is critical for manufacturers, specifiers, end users, and regulators to understand these best uses so users can understand what performs well, suppliers can make a high-quality compost product, and designers can specify and receive a product best suited for the application. This will improve bioretention performance and confidence from specifiers and end-users, minimize pollution potential, and ultimately increase acceptance and use of compost in critical green infrastructure stormwater best management practices. The final report is the culmination of joint effort between CREF and U of M and includes a literature review and a virtual listening session. The systematic literature review (Erickson et al. 2022) reviewed and evaluated current published scientific literature on bioretention system performance with and without compost in the soil media to determine differences in effectiveness and performance. You can read the final report HERE.

Soluble Salts in Compost and Their Effects on Soil

The compost industry has met with resistance to the use of finished compost because of high electrical conductivity (EC) (ie. soluble salts) measurements. Soluble salts are perhaps the most misunderstood parameter in a compost test data report. Many specifiers assume all soluble salts are harmful to plant growth and that soluble salts in compost directly translates to negative plant response. This leads to compost specifications based on this assumption and results in overly narrow soluble salts ranges for compost use. What is not understood is that soluble salt (or EC) is a total number assigned to an entire category of charged elements found in compost and include parts of the NPK, micro and macro nutrients beneficial, even essential, to plant growth.

The purpose of the soluble salt literature review was to gather the available peer reviewed scientific research regarding the salt content of finished composts causing the high EC. The goal was to identify the specific types of salts and whether those salts are beneficial or harmful to plant growth.

The paper has recently been published in Compost Science & Utilization (CS&U).  Published by Taylor & Francis, CS&U is abstracted in the prestigious Science Citation Index with an impact factor of 0.969.  Publication of such work in an internationally recognized peer-reviewed research journal gives the work an extra level of recognition in the scientific community and reinforces CREF’s commitment to understanding and communicating the science involved in composting.  The full paper is available open access, for Free, HERE.

Researchers from the University of Wisconsin-Oshkosh were hired by CREF to do this project.

Greg Kleinheinz received his BS in Biology and Chemistry from Northern Michigan University and his Ph.D. from Michigan Tech University.  He currently serves as the Viessmann Chair for Sustainable Technology, Director of the Environmental Research and Innovation Center, and Chair of the Department of Engineering Technology. Dr. Kleinheinz has worked on projects related to environmental contamination and beneficial reuse and remediation for over 20 years.   The Environmental Research and Innovation Center (ERIC) is a contract research and development facility at UW Oshkosh that partners with organization throughout North America.

Carmen Thiel is the Laboratory Manager for the ERIC Lab. She has been involved in compost testing since arriving at the ERIC in March of 2017. In addition, she has a BS degree in Water & Soil Resources from UW-Stevens Point and previously worked for a land conservation department on soil, water, and plant health issues, specifically with nutrient management. Her background working for a land conservation department as well as a crop consulting company demonstrates she is well versed in plant nutrition, soil, and compost management topics.

A Literature Review and Analysis of Compost Aeration Emissions Measurement Methods

This literature review evaluated current compost emissions testing methods to provide an analysis of current practices as well as constraints associated with those practices and potential new approaches that have the potential to be more cost-effective while providing an acceptable level of accuracy. The initial part of this review has been completed. It is currently in the process of getting ready to go out for peer review. If accepted, the CREF will make that full version available, open access, as it did with the soluble salts project.

The researchers chosen to do this project, Andrew Carpenter & Lauren Souther, Northern Tilth and Sally Brown, University of Washington, were asked to do the following:

  1. Identify current air emissions testing methods used at compost facilities and costs associated with these methods, and interview source testing companies that gather the samples and the analytical laboratories that analyze the samples and,
  2. Interview compost facility owners who contract out these services to corroborate cost data and understand how they view the testing services they have access to, and
  3. Review and analyze air emissions data sets generated by previous testing of air emission sampling at compost facilities to assess the strengths and weaknesses of these methods, and
  4. Review peer-reviewed publications where alternative sampling and analysis methods have been used to measure air emissions from composting facilities.
  5. Recommend next steps for development and testing of alternative sampling and analysis methods required to bring them into practice.
The project researchers wrote a shorter version of the potential peer-reviewed paper summing up their findings. You can read that version HERE

Andrew Carpenter, founder of Northern Tilth, is a certified soil scientist, certified crop advisor and certified nutrient management planning specialist. Andrew has recently joined the CREF Board of Trustees.

Dr. Sally Brown is a Research Associate Professor, Ecosystem Science Division, College of Forest Resources, University of Washington in Seattle. Sally has done other projects for CREF including as one of the editors of the Compost & Climate Connection.

Lauren Souther graduated with a BS in Wildlife Biology from Unity College. She currently works as a Nutrient Management Planner for Northern Tilth.

Compostable Plastics Literature Review

Recently, the US Composting Council worked with Nora Goldstein and Craig Coker, with BioCycle Associates, to create the Compostable Products Primer exploring the evolving role of compostable products the marketplace over the past 30 years. It looks at the relationship industrial composting facilities have with the compostable products market and the acceptance of these products at compost facilities. Through the research done for this primer, a compostable plastics literature review was conducted. The literature review explored the following questions:
  1. What is the formation and fate in the environment of microplastics derived from compostable bioplastics under industrial-scale composting conditions?
  2. What are the factors that optimize the disintegration and biodegradation of compostable bioplastics during industrial-scale composting, including additives?
  3. What are the similarities and differences of biodegradation under anaerobic and aerobic conditions?
Because of CREF’s commitment to expanding compost-related research, the authors of the Compostable Products Primer and the USCC worked with the CREF to create a Compostable Plastics Literature Review highlighting the different research papers that were reviewed for the primer.