CenUSA Bioenergy Project: What Master Gardeners are learning about biochar, soils, and bioenergy (Part 1)


As part of the CenUSA Bioenergy research project, Extension Master Gardeners in Iowa and Minnesota are doing research to explore to see if biochar makes a good soil amendment for growing flowers and vegetables in the home garden.


What is biochar?  In a nutshell it is a new term for an old product…charcoal.  The soil scientists working on the CenUSA Bioenergy project are really good about explaining the differences between biochar based on the type of biomass it’s processed from or the way it is actually processed.

All Biochar is Not Created Equal, Which is Why We are Researching Its Use in Gardens

Because not all biochar is created equal,  when people get excited about wanting to add biochar to their gardens (or garden soils, technically), I try to encourage them to wait until there is more research and some credible labeling and standardization of biochar products before diving in.  There is a lot of  hype and misinformation that’s out there.  I can’t imagine what would happen if people started adding biochar to their soil every year much like fertilizer…if too much is added, it could prove to be pretty negative on the soil (with long term consequences).

Different materials and processing lead to variable biochar outcomes

Since biochar is a form of carbon, it can last in the soil for decades (depending on how it’s processed). Biochar is a complicated product. It can be processed from many materials.  There are many ways of processing it which also produces differing results.  When those variables are combined with a variety of soils, it results in many different outcomes. I have learned that in current research projects, there are some plants that have shown beneficial results from using biochar such as flowers or leafy kale and in other cases there were negative results such as tomatoes and in some trials, adding biochar as a soil amendment made no substantial difference in plant growth.

With that said, there is still a lot of research that needs to take place before using biochar to grow flowers and vegetables in the home garden.  Some careful research has shown that in some soils, especially sandy or nutrient-depleted soils, biochar has shown improved plant yields on select crops.  This may be due to better soil structure and improved moisture and nutrient retention from the use of biochar. On the flip side, there are some biochars that have been tested and had some negative results  – showing that it may actually rob the nutrients from already healthy soils, and some biochars may actually possess potentially toxic chemicals. Researchers on our project and elsewhere are also trying to measure if there is a net benefit of reducing atmospheric carbon dioxide when it’s weighed against the amount of carbon needed to produce it.

In closing my thoughts on biochar, I would encourage people to do their homework and search credible sources for research that has been conducted.  The use of biochar seems to raise more questions than answers. I believe it will take more time and research before “designer” biochars can be regulated and sold for the home gardener.

The Story of Extension Master Gardeners Researching Biochar Has Just Begun

In 2012, Extension Master Gardeners were asked to help support biochar research for this Cenusa Bioenergy project by planning, preparing, and ultimately planting test plots in concert with University of Minnesota and Iowa State University. I have been the project coordinator on this project for the past year for the University of Minnesota test plots.  It has been a year of learning and trial and error (which is really what is so fun and rewarding about this project)!

In the next couple weeks, I’ll get a chance to tell more about our research story on this blog, including how we selected our biochar, what safety recommendations we used, how we chose our test plots, what we planted, how it grew the first year and what we learned in our first season that will help us in the coming year’s research.

In the meantime, you can begin to see how Master Gardeners are involved in this much bigger project to create a midwestern regional system for producing advanced biofuels in this 2012 CenUSA Bioenergy Overview YouTube video


by Lynne Davenport-Hagen
University of Minnesota Extension
Master Gardener Program Coordinator-Anoka County
CenUSA Biochar Research & Display Garden Project Coordinator-USDA NIFA Grant


“The CenUSA Bioenergy project is supported by Agriculture and Food Research Initiative Competitive Grant No. 2011-68005-30411 from the National Institute of Food and Agriculture.”




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