Biochar at Level 1
The biochar from a combined heat and biochar gasifier fueled by uniform biomass typically has a specific surface area between 250 and 600 m2 per gram, depending on temperature and the type of biomass (Physical and chemical characterization of biochars derived from different agricultural residues). Such biochar provides a lot of surface area for fermentation microbes at Level 1. Dr. Preston confirmed that “the conversion of crude protein to true protein in fermented cassava pulp is improved by the addition of biochar” (Saving the Planet for Future Generations). In another study by Preston and Leng, we see that “biochar acts as a support mechanism for consortia of microorganisms acting synergistically to enhance the rate of fermentation of starch and therefore the efficiency of microbial growth” (Biochar improves the protein-enrichment of cassava pulp by yeast fermentation).
When biochar is added in small quantities to feed (generally less than 1% on a dry matter basis), biochar significantly promotes cattle growth (Biochar reduces enteric methane and improves growth and feed conversion in local “Yellow” cattle), poultry growth (Biochar in Poultry Farming) and fish growth (Feeding biochar or charcoal increased the growth of striped catfish and improved water quality).
In the first study the live weight gain of cattle increased by 25% through the addition of 0.62% rice hull biochar (dry matter basis) to their diet, and the production of enteric methane was reduced by 22%. When a source of nitrogen was added along with the biochar, the reduction in enteric methane reached 41%. In the second study, we see that the addition of 0.6% biochar in feed improves growth in young chickens by 17%. The authors recommend adding biochar to the fermented feed of chickens. In the third study, biochar increased the growth rate of catfish by 36%.
When biochar is added to feed, it ends up, of course, in the solid waste of the animals, poultry or fish that ate the feed. Biochar prevents, for the most part, the escape of nitrogen from fresh manure, as demonstrated in the second study. When biochar is added to fish feed (not to the water of fish), water quality is improved, as values for total ammonia N, NO2-, PO43– and COD are all lowered, as demonstrated in the third study.
In Rice distillers’ byproduct and biochar as additives to a forage-based diet for growing Moo Lath pigs; effects on growth and feed conversion, we see an improvement in weight gain between 20.1% and 22.9% when 1% biochar was added to the feed of pigs.
To understand why biochar increases animal, poultry and fish growth: it likely facilitates the “formation of biofilms as habitats for gut microbiota,” as Dr. Preston explains. Dr. Preston has done more than 25 studies on rice hull biochar from my gasifiers, and he sums it up so well when he writes that the role of biochar “is much wider with potential application in all components of farming systems that involve microbial activities” (Preston 2015). In this study on goats (Effect of biochar and water spinach on feed intake, digestibility and N-retention in goats fed urea-treated cassava stems), Preston and Leng saw that the combined effect of biochar and water spinach increased feed intake by 41%, and that “biochar increased daily N retention by 46% and the biological value of the absorbed N by 12%.” The explanation given for this extraordinary effect: “We suggest that biochar effectively functions as a “prebiotic” – stimulating the activity of beneficial microbial communities through its support for biofilms in the digestive tract of the animal.”
Biochar at Level 2
When BSF larvae eat manure containing biochar, biochar enhances larval growth and ends up in larval residue. When red worms eat larval residue containing biochar, biochar enhances red worm growth, and it combines with humic and fulvic acids in vermicompost to create by far the finest fertilizer that exists (vermichar).
Vermicompost can be described as a humus-like material, containing “17-36% humic acid and 13-30% fulvic acid of the total concentration of organic matter” (Effects of Vermicomposts on Plant Growth). These two acids are quite effective in making minerals and other nutrients assimilable to plants; for example, in dissolving silica and making it available to plants, or in making phosphorous available to plants growing in acidic soils where phosphate ions precipitate with Al and Fe cations. Fulvic acid can break down certain toxic herbicides and pesticides within soil. It can be used as an effective antimicrobial: Antimicrobial Efficacy of Fulvic Acid Formulations against Escherichia coli O157:H7 on Bagged Organic Leafy Greens at Refrigeration Temperatures. It can be used as a foliar spray: Effect of foliar application of fulvic acid on plant growth and fruit quality of tomato. It can even be used in human medicine (Fulvic Acid: a Substance Vital to Human Health).
At Level 2, activating biochar does not mean mixing biochar with vermicompost or soaking biochar in vermicompost tea. Activating biochar at Level 2 means, above all else, letting biochar pass through the gut of the worm where humic and fulvic acids are formed.
Biochar at Level 3
Similarly, at Level 3, activating biochar does not mean mixing biochar with compost or soaking it in compost tea. Activating biochar means, above all else, composting biochar along with fresh Type 3 waste in a thermophilic process in which humic and fulvic acids are formed.
This strategy of biochar co-composting enhances nutrient use efficiency within the composting process, and it results in “better material flow management” (Synergisms between Compost and Biochar for Sustainable Soil Amelioration). Biochar stabilizes labile organic matter within fresh Type 3 waste, and this results in “higher and long-term C sequestration potential” compared to compost or biochar individually applied to the soil. “Co-composting of biochar and fresh organic material is likely to have a number of benefits compared to the mere mixing of biochar or compost with soil.”
In the presence of Type 3 biomass that is fresh and easily degradable, the surface oxidation of biochar takes place. This enhances the capacity of biochar to chemisorb nutrients, minerals and dissolved organic matter. “The overall reactivity of biochar surfaces probably increases with composting.”
Biochar also serves as a bulking agent and improves oxygen availability within composting materials. Increased oxygen availability stimulates microbial growth and enhances respiration rates. Biochar provides habitats for composting microbes residing within biofilm. Biochar retains moisture and makes moisture available to composting microbes. Biochar therefore increases the speed and efficiency at which composting microbes do their job.
Several studies indicate that as much as 50% of the pre-compost blend by weight might consist of biochar. “The composting of biochar could be successfully conducted over a wide biochar/organic material ratio covering up to 50% biochar by weight.” If during composting the composting mix begins to dehydrate, human urine can be added instead of water. Urine hydrates and adds nutrients. A lot more to come on urine processing toward the end of this paper.
If one wants a true terra preta soil, simply adding biochar to soil does not give the desired effect. The terra preta concept involves a whole lot more than biochar, or a superficially activated biochar, viewed as an isolated input into soil. It involves above all else biochar that passed through the gut of a larvae or worm at Level 2, or biochar that was co-composted with Type 3 waste. Black soldier flies are indigenous to the Amazon Basin, and they surely played a role in eating human and animal excrement, and in passing on their residue to red worms and earthworms inhabiting terra preta soils. The peregrine earthworm, found in the Amazon, is known to ingest pieces of charcoal and mix “them in a finely ground form with the mineral soil.” Decomposed or charred animal bones and tortoise shells were at times part of the terra preta mix. More about the importance of charring bone further on in this essay.
What is sorely missing in many discussions about biochar is its cascading multi-functionality.
Biochar in Soil
When biochar finally makes its way into the soil in vermicompost or compost, it has a mean residence time in soil on a millennial time scale (between 1,300 to 4,000 years). Incorporating fresh biochar directly into the soil is not recommended, since biochar can fulfill so many important functions before it reaches the soil. But once it cascades its way down into soil, the marvel of biochar continues.
Some speculate that rice hull biochar “has been used for several thousand years since the beginning of rice cultivation in Asia” (Introduction to the Pioneer Works of Charcoal Uses). Biochar increases the ratios of methanotrophic to methanogenic bacteria in paddy soils. This results in reduced methane emissions (Mitigating methane emission from paddy soil with rice-straw biochar amendment under projected climate change and Mechanisms of biochar decreasing methane emission from Chinese paddy soils). As biochar reduces methane emissions and as nutrients are retained within soil, this increases rice yield. Rice hull biochar with a bit of compost has been shown to increase rice yield in Cambodia by as much as 300% (Trial on Biochar Utilization in Rice Crop on Tuk Vil Luvisol).
Sisomphone Southavong, T.R. Preston and Ngo Van Man did an experiment in growing water spinach (Effect of biochar and charcoal with staggered application of biodigester effluent on growth of water spinach (Ipomoea aquatica). The water spinach in the control group received no charcoal or biochar. The water spinach in the second group grew in soil amended with charcoal. The water spinach in the third group grew in soil amended with rice hull biochar. Water and fertilization were the same in all three groups. The results can be seen in the picture below.
In another experiment Dr. Chhay Ty and Dr. Preston applied 5 kg of rice hull biochar per m2 to a plot of mustard greens (Effect of different levels of biochar on the yield and nutritive value of Celery cabbage (Brassica chinensis var), Chinese cabbage (Brassica pekinensis), Mustard green (Brassica juncea) and Water spinach (Ipomoea aquatica). To a second plot of mustard greens they applied no biochar. But this second plot received the same water, fertilizer and management as the first. The plot with biochar yielded almost four times more weight in mustard greens than the plot without biochar, an amazing 400% increase in growth.
But the improvement here was not merely quantitative. The mustard greens with biochar had 40% less fiber and 35% more protein than the mustard greens grown without biochar. Experiments with other vegetables were also carried out. With water spinach there was a 39% increase in growth. With Chinese cabbage there was a 100% increase in growth. With celery cabbage there was a 300% increase in growth. In a personal communication Dr. Preston stated that “Olivier gasifier stoves have been the driving force for nearly all the work we have done on biochar.”
In fulfilling the many functions outlined above, biochar has a much greater value than the low-grade biomass from which it is derived. This means that in combined heat and biochar gasifiers, we have high-grade heat – for cooking, boiling, grilling, parching, roasting, toasting, drying, fry-cooking, distilling, absorption refrigeration and so forth – at a cost less than zero. Burning lump coal, coal slurry briquettes, wood, charcoal, propane, butane or natural gas – in no way can compete. Where else on earth is high-grade heat produced at a profit?
Arbuscular mycorrhizal fungi, found in conjunction with 80% of vascular plant families, grow exceptionally well in the presence of biochar (Mycorrhizal responses to biochar in soil – concepts and mechanisms). A study in Japan revealed that when one kilogram of biochar was added per square meter of volcanic ash soil, “alfalfa associations with AM fungi increased by 40-80%” (Inoculation with arbuscular mycorrhizal fungi: the status quo in Japan and the future prospects). Vermicompost also promotes the growth of AM fungi (Vermicompost stimulates mycorrhizal colonization). But why are AM fungi so important within agriculture?