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Is Biochar an Option for Soil Health By Steve Alspach, State Soil Scientist

            With the recent ice storm throughout central Oklahoma many of us have a lot of wood to dispose of due to the broken trees. Living in the Cross-timbers we literally have tons of Blackjack and Post Oak limbs to dispose of. My choice? See if I can put some of that carbon source to good use and create biochar to be used in my garden.

            Biochar is, essentially a carbon source that has be oxidized to point where the volatile compounds removed by burning to a point where the structural carbon is all that is left from the source. The end product has the ability to assist in soil health by adding Cation Exchange Capacity (CEC) and providing an excellent environment for the soil microbiology to thrive.

            I would to preface this article by saying I don’t have any biochar chambers or other special equipment for creating the biochar so my process is simple but maybe not highly efficient. The process will work well for a garden, flower beds or other small growing areas. It would be difficult to expand to farm level, field level extent.

biochar step one


Step one is to create the char by burning the downed wood. For this step I used a simple firepit ring that we have in our yard. (see image 1). The process was simply burning enough wood to create a good bed of coals and letting them burn long enough to form a cover of ashes on the surface. This process cuts of the oxygen supply and slows the burning process. After about 24-48 hours the coals are ready to be removed, cooled and washed.


Biochar step two


Step two involves cooling the coals using water. For this step I used an old galvanized wash tub to add water and stir to stop any of the burning process. This leaves a slurry of the biochar and ash that is mixed together in the tub. (see image 2).




Biochar step three


Step three involves washing the biochar to remove the ash portion of the slurry. For this step, I used 2 buckets. One bucket has holes drilled in the bottom to allow wash water to flow through the bucket. I captured this wash water in the second bucket so I could apply it to my garden. The ash will have some level of nutrient value that was stored in the wood. The result of this step is clean biochar and an ash/water slurry (see image 3).



Biochar step four


The final step in this process will be to combine the biochar I have created and mix it with compost that has been making all year in my compost pile. The compost has a high level of biologic diversity and is filled fungi, bacteria, protozoa etc. The mixing will “activate” the biochar with this biologically diverse community and I will apply this mixture to my garden which currently has a cool season cover-crop blend growing on it (see image 4).



While not plausible for a large-scale operation this process is a way to get some good out of the damage of the recent ice storm.