The Wisdom of Agricultural Co-Composting of Biochar and Animal Manure

SoilMatrix Newsletter No. 17

The Wisdom of Agricultural Co-Composting of Biochar and Animal Manure

Cattle Feeding and Over Wintering

The topic of co-composting animal manures with biochar has risen in importance since about 2010 with the publication of an increasing number of research papers on this topic, including an astounding research discovery at the Canadian Light Source facility in Saskatoon, Saskatchewan.  This research demonstrated the way in which organic materials physically coat the surfaces of biochar particles over a period of time during co-composting of biomass with biochar 2.

Land application of compost is an age-old agricultural method of returning nutrients to soils.  However, compost additions to soils can result in substantial emissions of greenhouse gas, especially N2O, which needs to be controlled during making and using compost containing high N-loads, such as chicken manure.  Some farmers in some countries are now pursuing the option of adding granulated biochar to animal bedding for the co-benefits of improving animal health and enhancing the eventual composting value of this material.  The eventual applications of co-composted biochar-manure mixtures is demonstrating benefits for soils and plants.

We already know that biochar blended with finished compost makes a great soil amendment to promote healthy plant growth.  All you need to do is run a Google search to find a vast amount of information on this.  However, why add biochar to animal bedding material destined for manure compost production?

Example of biochar spread on top of animal bedding prior to cleaning out an animal shelter in the spring

What we already know about biochar’s nutrient holding and moisture retention capabilities along with its ability to stimulate microbiological populations of beneficial bacteria and fungi when amended into soils, leads to the possibility for these added benefits for co-composting with other organic materials.  Significant numbers of research projects have been underway and are continuing with positive biochar-manure co-composting benefits being substantiated.  These benefits include:

Example of creating a manure-biochar compost pile with a manure spreader
  1. Shorter composting time requirements 1
  2. Absorbs leachate generated during the composting process 2, 3
  3. Absorbs nutrients in the leachate and in the organic matter of the compost
  4. Retains moisture during the composting process
  5. Reduced N2O emissions 4, 5 6, 
  6. Reduced CH4 emissions
  7. Reduced NH3 emissions
  8. Provides a bulking agent
  9. Reduces odor
  10. Increases Cationic Exchange Capacity (CEC) 5
  11. Minimal degradation of the carbon material is observed, rendering it an effective means of carbon sequestration 5
  12. Surfaces of biochar particles become coated with organic material resulting in significant plant available nutrients 2, 3

Although these benefits have been demonstrated by small plot tests and field trials, in some cases, much more field experimentation and demonstration will be needed.  AirTerra is seeking to work with experimental farmers to supply the necessary high-quality biochar to fully verify these findings.  We are anticipating a revolution in regenerative farming as a result of these early (or late depending on how you see it) explorations of what we and others are calling “Carbon Farming”.


  1. Ted Talk on biochar-manure co-composting
  2. Nikolas Hagemann, Stephen Joseph, Hans-Peter Schmidt, et al, “Organic coating on biochar explains its nutrient retention and stimulation of soil fertility”, Nature Communications, October, 2017,
  3. Canadian Light Source, “Scientists discover why biochar fertilizers work so well”,
  4. Claudia Kammann, et al, “Biochar as a tool to reduce the agricultural greenhouse-gas burden – knowns, unknowns and future research needs”, Journal of Environmental Engineering and Landscape Management,  Published on June 28, 2017
  5. Katharina Prost, “Biochar Co-Composting with Farmyard Manure”, Journal of Environmental Quality, February 13, 2012
  6. Yinghong Yuan, et al, “Is Biochar-manure co-compost a better solution for soil health improvement and N2O emissions mitigation?”, EPA, 2017
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World Soil Day – Celebrate by viewing the movie “Dirt Rich”

SoilMatrix Newsletter No. 14 (World Soil Day!)

In honor of the upcoming “World Soil Day”, December 5, 2018, this SoilMatrix newsletter is dedicated to the importance of soil for sustaining life on Earth.

As a way of entering into this celebration, we are providing a link to the newly released movie “Dirt Rich”, filmed and produced by Marcy Cravat of Passelande Pictures.   Dirt Rich is being premiered at Film Festivals all over North America and recently won the “Earth Shaker” award at the Maui Film Festival.

Passelane Pictures is partnering with Dr. Mercola’s team to freely stream this movie until October 12, 2018, after which it is available for purchase or rent.

To access the link to this free movie screening, click here.

To access the link to this free movie screening, click here.

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The very best way to use your SoilMatrix Biochar

SoilMatrix Newsletter No. 13 (Biochar Co-Composting)

Making the very best possible use of your SoilMatrix Biochar…  in your compost.

This edition of the SoilMatrix Newsletter is all about using biochar in your compost-making process as a very good first step in preparing a great garden soil amendment.  If you want to know why adding biochar to your compost bin works so well, read on…

Compost made from kitchen scraps and yard waste with biochar as an ingredient


That’s right! If you are willing to be patient with your soil enhancing activities, sprinkle a cup of biochar into your compost bin for every 20 cups of added material and keep it blended with all the input materials remembering to keep close to a ratio of 25 to 1 carbon to nitrogen materials.  Biochar co-composting is probably the best possible way to prepare your biochar for your garden.


The SoilMatrix Garden on August 3, 2018












An average evenings harvest from the SoilMatrix Garden

We already know that biochar blended with finished compost makes a great soil amendment to promote healthy plant growth.  All you need to do is run a Google search to find a large amount of information on this.  However, why include biochar in the actual compost making process – “biochar Co-composting”?   I am suggesting this based on my own experience and a recent article published in “Nature Communications”1.  The article:  “Organic Coating on Biochar Explains its Nutrient Retention and Stimulation of Soil Fertility” is written by a group of well respected biochar researchers:  Nikolas Hagemann, Stephen Joseph, Hans-Peter Schmidt, and a host of others.

The secret is in the nutrient-rich organic coating that forms on surfaces of co-composted biochar.  Not only does this coating cover the outer surfaces of biochar particles, but it makes its way into the inner pores as well2. In the referenced article, a number of methods were used including high-resolution spectro-microscopy and mass spectrometry to observe the organic coating.  Moreover, a number of other measurements methods were used to determine that the organic coating contributes to moisture retention and nutrient retention.


  1. Nikolas Hagemann, Stephen Joseph, Hans-Peter Schmidt, et al, “Organic coating on biochar explains its nutrient retention and stimulation of soil fertility”, Nature Communications, October, 2017,

The authors of this paper also believe that biochar’s soil enhancing properties are determined by the formation of this organic coating on biochar surfaces and not the positive and negative charges on its surfaces as previously believed.   This means that biochar that is added to soils without having time to acquire such an organic coating, depends on the eventual formation of such a coating before all the benefits of biochar soil amendment is realized.

Although biochar is often quoted as having a number of positive impacts on soil properties and structure, i.e. porosity increase, nutrient and moisture retention, upward pH adjustment for acidic soils, and stimulation of beneficial microbes, no real detailed mechanistic understanding of how biochar positively influences plant growth has been provided – not until now.

High applications rates of up to 10 tonnes per hectar (1 kg per m2) have been recommended in the past, which is currently uneconomic for industrial large scale agriculture.  But recent research like that provided in the above article suggests that biochar should be combined with organic amendments (compost, animal manure, green manure, etc.) to increase soil fertility even while reducing the rate of biochar amendment.  However, the mechanism that is at play when biochar is amended with organic components is not yet fully understood.   A mechanistic understanding of how co-composting impacts biochar’s performance as a soil amendment is still needed to help develop lower cost organic biochar-based fertilizers that can promote higher crop yields with comparably smaller application rates of biochar.

The organic coating that has now been physically measured and observed on co-composted biochar was also observed to exist when biochar is aged in the soil along with organic materials, but this takes some time to develop – possibly one or more seasons.

Stay tuned as this line of biochar co-composting research continues to reveal how this organic coating actually benefits plants.  Hint…it may have something to do with the benefits of soil organic carbon content for the health of soil microbiological life.

Butternut Squash



If you want to learn how this principle is being used in developing countries around the world see:

Give it a try and let’s continue to learn from each other.

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