A growing interest in Biochar

posted in: AIRE, Research, Sol Feliz Farm | 8

IMG_1291There is growing interest in using biochar to improve soil moisture, organic matter, and crop yields.  Biochar is basically reducing carbon from wood to a charcoal-like state and then using it to amend the soil.  I first heard about biochar in some studies of ancient Incan agricultural fields.  I then heard about some interest in conventional agriculture to apply the concept of biochar to large-scale production.  For example, in rice production there is typically alot of carbon left after the harvest that is usually burned off, contributing to the problems of carbon dioxide in the atmosphere  and climate change.  If the carbon that was once considered waste could now be considered a resource to improve soil quality and yields, we would all benefit.

We have an interest in the small scale application of biochar.  When we use the horno mud oven, we typically “drown” the fire and seal off the horno with mud.  It seems like these conditions are conducive to the creation of charcoal and biochar.  We gathered the charcoal left over from the horno-cooking process to test its application.  We screened this “biochar” into two size classes: coarse and fine.  The coarse charcoal will be used in experiments to test its effect on moisture retention in the soil and yield.  We understand that it is important to inoculate the biochar with compost and water before its use in the soil.  The fine charcoal will be used in trials for water filtration.  We will be doing trials on garlic and maize production this year.  Stay posted for the results of these trials, we are excited about the potential results!

8 Responses

  1. Ron McFarland

    Is there any value to recycle ashes from the fireplace back into the soil or compost pile?

    Is biochar somewhat similar to Humates?


    • Miguel

      I think some ashes are good, but I like to consider what my soils were used to before agriculture came. So I prefer to gather up the dry weeds that grew on site and burn them periodically. I also like to gather up the dry weeds, compost them, and apply it later. Ultimately, I think less is more when it comes to soil management and I think it is better to slowly nudge your soils into fertility than to risk overloading them with something that would be harder to remove than to prevent. So I have a wood stove but actually put my ashes in a bin and take them to the dump when I take my trash. If I didn’t do that, I might put some ashes in my field periodically and sporadically, but again, I prefer to keep with what might have happened in a more natural ecological context (i.e. wildfire in the short grass prairie) rather than potentially overload my system… Hope that helps…

      I think biochar is considered to be a precursor to humates and serves some of the same purpose in the soil like sites for water absorption and places for micro organisms to live. But unlike having to wait for thousands of years for humates to naturally form, biochar can be made relatively quickly and easily…

  2. Ron McFarland


    Thanks for the reply and sharing your ideas. I have been doing a bit of both and will keep your ideas in mind next time I clean out the fireplace.

    We have a piece of land in Taos that was an abandoned orchard that has a couple of pear trees that have survived without care for several decades and have been estimated to be over eighty years old – interesting to see – feel free to reach out and stop by some time – very awesome when in bloom.

    Best wishes

  3. riverbird

    We use wood ash in our composting toilet setup. If you have excess going to the dump, we would be interested in intercepting this material from you. I could handle a 30-40 gallon trashcan quantity at a time, depending on how much you generate.

    • Miguel

      I just took a 55 gallon drum full of ashes to the dump! Sorry about that… I have a composting toilet too and never thought of using ashes, sounds reasonable. I am composting based on Jenkin’s “Humanure Handbook.” It seems to be going well, we have our first batch of humanure coming out now after three years of composting…

      • riverbird

        We are also generally following Jenkins’ method. In our primary collection bucket we use a combination of straw, wood shavings, and a light dusting of ash to cover bizness. My idea with the ash is twofold, one it helps keep odors down and second, I figure it helps some with the final pH because the shavings we use are all pine which I guess is a bit acidic. We just pulled out our third batch, after about a 2-year composting period. Dirt looks good!

  4. riverbird

    p.s. To the point of your post here .. what is you method for doing the inoculation step with compost and manure? are you just basically soaking the charcoal in a compost tea?

    • Miguel

      I’ll bet the compost tea method will work and I may try it as well. For now, we put almost 5 gallons of biochar in a barrel with water and add about a gallon of high quality compost and stir like mad!

Leave a Reply