I am currently doing an internship with Deanne Bednar at Strawbale Studio in Oxford, Michigan. While here we a had a couple of guys come and do a biochar demonstration open for anyone in the community. Here is a summary of what I took from it along with a little extra research. First off, what is biochar? Basically, it's just charcoal that is used for soil amendment. It is created from the burning of wood or biomass (a renewable form of energy) under the exclusion of oxygen and is composed primarily of recalcitrant carbon which means that it stays in the soil for hundreds to thousands of years unlike labile carbon that will rot in matter of weeks to years. (Labile carbon is usually root residue or plant debris, also known as compost, that provide an important source of energy for soil microorganisms) Biochar has a long history for being used as a fertilizer but in the last thirty years research and use has accelerated. Recently, production of biochar is being suggested as a strategy to remove global-warming carbon dioxide from the atmosphere because of it's ability to produce oil and gas byproducts that can be used as a fuel providing renewable energy, thus meaning it could possibly help alleviate climate change.
How does it work? Biochar has a microscopic composition of countless small channels that can absorb water and nutrients up to five times it's weight. This is helpful through dry spells allowing it to moderate drought. These microtubules can store important bacteria and fungi which are what transports nutrients from the soil to the plant increasing the biological life of the soil and creating soil fertility. The important thing to know about biochar is that because of it's ability to absorb minerals if you don't charge it prior to soil application it will steal nutrients from the soil and harm your crops. Charging your biochar means loading it with nutrients, this can be done in many different ways. A few of the most common ways to charge biochar would be mixing it with compost, manure, or compost tea and the duration of your charge should be at least fourteen days. Specific instructions on charging your biochar can be found here. Once this is done you should crush your biochar into grain sized material making your biochar ready to be added your soil. We did this by putting it into a five gallon bucket and crushing it with a board. This is going to help improve your plant growth similarly to compost. However, as stated above, because biochar is a recalcitrant carbon it will continue to provide the nutrients you are needing in your soil basically indefinitely unlike your labile carbon compost which you will need to continue to add over the season because of the rate in which it breaks down. If you would like a more in depth and scientific explanation of how biochar works click here.
Why biochar? Biochar can reverse soil degradation reducing the leaching of nutrients and creating a reliable source of fuel and food production enhancing plant growth in places with severely nutrient depleted soil. It can be helpful in places with limited resources or fertilization material and lack of adequate water with it's ability to retain water and nitrogen and raise soil PH level. It can make farm lands more fertile reducing the leaching of nutrients and fertilizer requirement for extended periods of time, provide thermal energy for cooking, and with the addition of an engine could produce kinetic energy for making electricity. Here is a more in depth list of benefits.
How do I make my own biochar? Easy! Biochar can be bought, but it's way more fun to make your own! The method we used in the demonstration was the Hawaiian luau pit. I am going to copy and paste the instructions from http://hawaiibiochar.com/biochar-burn-demonstration/ because they explain it better than I can. First, a fire is started in the bottom of a pit, then dry wood is then added as fast as the fire will allow – you must always push the fire near to the point of smothering it, yet without actually smothering it. It is important to always keep a clean burning fire – no smoke. If it becomes a bit smoky, back off, let the fire catch up. If it is raging, add more wood to choke it out a bit. In this way you are constantly covering the char that has been made with fresh layers of wood, which become char, which are soon covered with fresh layers of wood, which become char, and so on. When you near the top of the pit or the end of your wood supply, you finish with small diameter wood. This chars quickly. Let the flames die down a bit, then voila – a large bed of red hot glowing coals. By this point, if you have done it right, the entire pit has turned to char. You can either hos e it down immediately, or cover it with soil to snuff it out. We hosed it down which seemed to be the most efficient. I was told that using soil you risk the chance of the fire restarting and turning everything to ash. We were instructed to use wood no more than two inches in diameter and once it got going the moisture content didn't seem to matter much as our wood was pretty wet. There are many different methods to making biochar, more can be found here and The Biochar Solution was a book recommended for learning about it more in depth.
I hope this post was informative and if you had little to no knowledge on biochar previously then you learned something new. Have a beautiful day!