Biochar 101

The actual process of biochar making takes about 20 minutesWhat does a farm intern do over the winter months to keep herself busy until the beginning of spring fun begins? Other than dream of crop rotation designs and new vegetables to try I also had the opportunity to attend an all day conference about biochar! Biochar is a very old concept that is only recently getting new attention for its carbon sequestering capabilities. The biochar story begins in Brazil when anthropologists discovered what they termed as “terra preta” or dark earth. When they tested the soil they found that it had very high levels of charcoal that had been buried thousands of years earlier. The impact of the charcoal made the soil more efficient in retaining water and nutrients and it can still be seen in the soil today.
    One major question I had going into this conference was what is the difference between charcoal and biochar? Hugh McLaughlin, a scientist at Alterna Biocarbon, answered that question for me. It was explained that charcoal is fuel that is used to cook and is made at around 300 degrees Celsius. Biochar on the other hand is a soil amendment and is made at 600 degrees Celsius. The key difference is the amount of mobile vs. resident matter. When you heat the biomass (woodchips, organic waste, manure, crop residues), to such a high temperature it becomes extremely stable and also creates a very porous structure. Good biochar should have high cation exchange capacity and absorption capacity – these are what make the biochar so beneficial to the soil. The main benefits of biochar are (1) improved moisture dynamic, (2) improved nutrient retention (N, P, K for example), (3) improved microbe survival during drought, and (4) improved plant – microbe synergisms. So, the idea is that biochar will keep carbon in the soil, rather than in the atmosphere, whilst simultaneously leading to improved soil health and larger crop yields.

Lighting the feedstock using rubbing alcohol and woodchips
    The process of making biochar involves collecting your biomass (referred to as feedstock) and lighting it on fire in a sealed container with very low oxygen conditions. Ideally the feedstock you use is coming from your farm or very near by, or else it kind of defeats the whole carbon saving notion. There are many different devices to make biochar – ranging from homemade “TLUD” (Top Lit Up Draft) Ovens, to much larger scale kilns and retorts. Click HERE for instructions on building yur own TLUD.  They did a biochar making demonstration at the conference using homemade TLUDs. There are also more and more companies that are selling biochar on the web. The most reputable companies mentioned at the conference (in which the biochar has been tested and approved) were Soil Reef, Encendia and Colorado Biochar. It was also emphasized that testing your biochar is really important before using it. Now that there is a market for it, there are companies using left over wood scraps from construction sites as their feedstock. Bad biochar can actually do soil more harm than good – so it is important to know the contents of your char.
    Once you have your biochar – you need to charge it. There are no nutrients inherent to the biochar, so the most common way to charge biochar is to combine the char with compost in a 50:50 ratio. You can add the char to the compost in the early stages of the compost and let it go through the process of composting. You can also mix it with finished compost and let it sit for about 2 weeks – this process is referred to as “weathering the char”. Compost is great but the benefits only last so long, the idea with biochar is that it absorbs the nutrients and makes them available to the plants for a much longer period of time. When you are ready to apply it to the soil, you can just add it by hand and mix it with the topsoil. Application rates range from between 1-10 tons per acre depending on your soil needs.    

    There is still a lot of research to be done in this field to determine the lasting benefits of biochar. But there are certainly a lot of exciting prospects and research projects being done. One farmer at the conference brought his own biochar to give out to fellow farmers as long as they promised to report back their experience with the char. The community of biochar users is still relatively small and there remains a need for more information on the use of biochar on small and large scales. I am happy to report that we have a bag of this precious biochar to experiment with this season at the farm. We will continue to report on our findings and hopefully will have some record yields!  

 Voila! Biochar created!

Compost is Nice

AFTER
For all of us who lug their kitchen scraps outside in the cold and dark....who scour their home looking for brown material (carbon) to match the easier to find green matter...who layer their compost bin precisely as outlined in the textbooks...who turn their pile daily to ensure the proper aerobic bacterial population....good for you. For those of us who simply throw anything we can find into the pile and manage to turn it when the inspiration or energy seems to strike (once a week)....good for us too! For this week HMG has finally produced some really nice compost following the lazy plan.

Compost when finished is a nice sight. Money savings becomes real, a forty pound bag of compost can cost between 5-12 dollars depending on where you get it, plus you have to take time to transport it as well as carry it everywhere.

Using a three bin system, HMG has produced what appears to be about 6-8 forty pound bags worth this season. Adding kitchen scraps, brown vegetable plant branches, occasional leaves (not too many) and a sprinkle of fireplace ash, we have made some pretty respectable looking compost.

We have found with minimal attention compost is really not difficult to make. The most important aspects are to make sure you get some brown matter in there as well as to periodically turn the pile so as to prevent anaerobic bacteria from kicking in. You will know if this happens as your compost pile will begin to smell like takeout fish that was left in the car overnight. If this happens, simply turning the pile over a few times instantly cures the problem. We have found a small pitchfork the best for doing this.

BEFOREApplying the compost to needy beds is definitely a great feeling. For those of us who do this without the benefit of high heat compost, which is usually done with machine turned piles or piles which have air blown into them, we will see a nice seedling bed soon of every vegetable we have eaten for the past 6 months as those seeds have not died in the pile. Obviously this is not desired, although seeing 200 tomato seedlings in a 10 x 4 foot raised bed is interesting, simply raking them in or pulling the seedlings seems to be the best management option....and is there anything more sustainable then making your own compost? I don’t think so!

Charlie