Biochar and Compost: Exploring the Synergies - Compost 2020 #compost #uscc

Tom Miles

Biochar enhanced compost products have been marketed for many years. Presentations at a Compost 2020 conference session, “Biochar and Compost: Exploring the Synergies,” showed how research and commercial formulations have advanced to show how biochars can be used to benefit composting, soil amendment, and carbon sequestration.


Research and practice were presented at the Compost 2020 conference session, “Biochar and Compost: Exploring the Synergies”. Dr. Doug Collins, Washington State University Center for Sustaining Agriculture and Natural Resources, Puyallup, WA, described his experiments composting wood shavings, biosolids, and biochar in an aerated static pile (ASP) and compared it with previous work. Interesting results included co-composting temperatures which did not rise higher than compost alone, and nitrogen fixation in spite of the high pH from high rates (40%) of biochar in a blend which should have driven off nitrogen. Instead Doug showed that it was captured in the compost.  

Keith Vodraska, Cool Planet, Colorado, described Cool Terra® processed coconut and pine based biochars and their impact in trials at The Ground Up compost in Houston, Texas. Keith showed how Cool Terra biochars improved plant/crop germination and establishment and increased plant vigor, growth, and health in both roots and shoots. With vermicompost Cool Terra biochars improved root growth in tall fescue, and reduced water and odor in composting. Keith showed how they improved survival of inoculated bacilli, elevated pile temperatures, reduced e. coli, and improved survival of microbial population.  Cool Planet will continued testing their biochars in compost.  

Jon Nilsson of Chargrow®, Ashville, North Carolina, described his Biochar Source™, the types of biochars that he uses, how he sees biochar benefitting compost quality through high stability, increased nutrient retention, increased water holding capacity, structural stability, increased beneficial soil microorganisms, reduced nutrient leaching, and reduced fertilizer requirements. He showed how adding Biochar Source at 20% by volume to compost improved production in tomatoes, potatoes and corn, and enables access to high value markets in trees and urban landscaping. Standing in for Peter Hirst of Symsoil® in California, Jon described Symsoil® V50 (50% Robust compost and 50% fungal infused biochar) and Symsoil® Grow Cubes. Symsoil® products are co-composted to catalyze the soil food web. Jon showed the results of using Symsoil products on broccoli, pumpkin, wine grapes and cannabis. He showed how both Chargrow® and Symsoil® use biochars to increase the value of composts.

Stan Slaughter, Missouri Organic Recycling, Kansas City, Missouri, uses biochar from Terra Char in Missouri. Missouri Organic Recycling produces more than 50,000 cubic yard of compost per year. They were inspired to use biochar from the experience JR Bollinger had with biochar in strip tillage of corn in 2015. The got started in biochar with the help of David Yarrow and the encouragement of a local farmer. They have produced more than 1500 CY of Green Frontier Compost in three years which contains 16% biochar by finished volume. They have added 20% Green Frontier Compost to more than 3900 CY of compost mix. Testimonials show that they have established sustained markets for their products.

During her keynote speech to close the conference, Dr Sally Brown, University of Washington, presented a slide showing how biochar possibly enhanced TAGRO when growing hemp. TAGRO is a soil amendment produced by the City of Tacoma from biosolids and recycled organic materials as growing media, micronutrient, and phosphorous sources. While not statistically significant the results from adding biochar suggest further experiments. Her talk “How to Drawdown and Rise Up” showed how compost is common to many tools listed by Project Drawdown to address climate change. Biochar can be an important component of compost.

The “Biochar and Compost: Exploring the Synergies” session generated much discussion. Compost producers were particularly interested in sources of biochar in their areas. Recordings and slides from Compost 2020 are available to non-attendees from the US Composting Council online store.