21st Annual Vermiculture Conference at NC State

by Jesse Wiser


North Carolina State University hosts an annual conference on all things worms, organized and emceed by Dr. Rhonda Sherman, one of the leading experts on vermicomposting in the United States, and author of The Worm Farmer’s Handbook, our go-to resource for vermicomposting. This year’s event took place on October 22-23, and drew 180 attendees, some of whom dialed in on Zoom. The schedule was well-structured, with educational presentations building off each other and plenty of time for networking in between.

The first round of presenters focused on scientific aspects of worms and worm castings. Dr. Mac Callaham of the USDA Forestry Service detailed worm biology and identification, and explained the importance of keeping vermicomposting systems contained, so that invasive species do not enter local ecosystems and destroy forest litter and native millipede populations. Dr. Kristin Hicks from the NCDA described the chemistry involved in producing quality vermicompost, such as including plenty of calcium but low levels of soluble salts in feedstocks. She recommended an initial carbon : nitrogen ratio of 30:1, in order to keep the vermicomposting process aerobic (enough carbon) while allowing the microbes to produce inorganic nitric compounds for plant consumption (enough nitrogen). The final science-focused presentation was delivered by Dr. Jacob Parnell of Biome Makers, who discussed his company’s method of analyzing microbiology in soil and vermicomposting samples. Their analysis focuses on grouping microbes by the function they perform in the soil ecosystem. Some of his points were expanded and further detailed by Dr. Zack Jones’ later presentation.

The next series of presenters described various practices within the field of vermiculture. First up was Matt Ball, who simultaneously operates Red Mountain Soil Ecology, a Soil Food Web biology analysis and consulting firm, and NC State’s compost facility. Matt explained why pre-composting materials prior to vermicomposting is a good idea, for several reasons – reduction in heat and volume, homogenized material, chemical benefits, etc. We hope to incorporate some of his practical guidelines in later blogs. Another university composter, Sean Barton, described setting up and running a hoop house-enclosed vermicomposting system at the University of Michigan, which is able to operate in cold weather.

Pivoting away from a focus on vermicomposting, Samantha Flowers of Meme’s Worms in southern Georgia detailed her worm breeding and shipping operation, and discussed how she grew her operation from a project with her grandson into a successful business located within a 22,000 square foot warehouse. Her talk was followed by an extremely enjoyable presentation from the very British Max van Praag, who runs a one-man vermicomposting business named Pluvr in Washington DC. The name is derived from the plover bird, which enters crocodiles’ mouths to clean their teeth; Max considers himself “Washington DC’s plover.” Max collects food scraps from upscale restaurants and runs them through an in-vessel aerobic composting system, an aerated static pile system, and a CFT vermicomposting system. He then mixes the vermicompost with other soil materials and sells it to small growers and landscapers, including the groundskeepers of the Smithsonian properties.

The next presentation was particularly impressive and forward-thinking. Dr. Zack Jones began applying DNA sequencing analysis to several different natural soil inputs, and discovered that vermicompost contains an incredible level of microbial biodiversity compared to other materials. This prompted him to undertake a multi-year project analyzing vermicompost samples from different geographical locations, produced from a wide range of feedstocks. Zack compiled the results to determine a “Vermicompost Core Microbiome,” consisting of specific bacterial strains that play beneficial roles in plant growth and disease resistance by producing compounds such as auxin, giberellins, and siderophore. The basic implication of Zack’s research is that regardless of feedstock and other factors, most vermicompost will contain excellent levels of plant-promoting bacteria. Zack has recently started a business, Aggrego Data, to perform DNA sequencing analysis on any sample product, and will continue to present his findings as his range of data expands.

Finally, Troy Hinke, who works for Urban Worm Company as well as running Living Roots Compost Tea, presented on compost tea creation and application. Troy has an impressive resume including managing compost at the Rodale Institute and working with Dr. Elaine Ingham. His presentation was geared toward smaller scale applications, with brew sizes in the 5-50 gallon range. He offered a ton of practical advice with the scientific reasoning behind it. For instance, he made the distinction between an aerobic liquid amendment and leachate from composting / vermicomposting operations, which is sometimes mistakenly called “tea”, but is anaerobic and could contain pathogens.


Here are some other takeaways from the conference, in order of presenter:

  • Glyphosate has been shown to kill worms (Dr. Callaham)
  • Vermicompost may have a higher pH than the soil it is applied to, but it will not raise the pH of the surrounding soil (Dr. Hicks)
  • Plants like a particular soil pH range because pH controls nutrient availability. For instance, blueberries like a lower pH because iron becomes more available. At a very low pH, many micronutrients become overly available and could become toxic (Dr. Hicks)
  • Unsalted peanut shells are a good feedstock for worms, since they contain the target balance of carbon and nitrogen (Dr. Hicks)
  • Vermicompost can become anaerobic if stored over time (Dr. Hicks)
  • Pre-composting lowers the biological demand for oxygen in a vermicomposting system, helping to maintain aerobic conditions (Matt Ball)
  • Recently thermophilic compost should only be added to a vermicomposting system in a 1 – 1 ½” layer to prevent the materials from reheating (Matt Ball)
  • Meme’s Worms ships their worms in dry peat moss because it insulates the worms; a wetter material would respond more drastically to higher and lower temperatures during transit (Samantha Flowers)
  • Winch cables in standard CFT systems can rust through and break (Max van Praag)
  • Most vermicompost seems to be bacterial dominant (Dr. Jones)
  • Adding humic acid to chlorinated water will bind chlorine ions, making it more biologically friendly (Troy Hinke)