An excerpt from Acres U.S.A. Magazine View this email in your browser Share Tweet Forward Biochar: Prepping it for Soil Application

by DAVID YARROW

To properly prepare biochar for optimum effec­tive use in soil, there are four fundamen­tal steps: moisten, micronize, mineralize and microbial inoculation.



MOISTEN

The first step is to add enough water to moisten char without it becoming wa­terlogged.



Fresh from a production burner, char is bone dry. It’s heated to over 500°C, and hardly has a molecule of water in it. But water is the first ingredient to cook up biological life. Without water, even earth­worms avoid char. But properly moist, worms like char mixed with their food, and microbes rapidly move in to colonize the char.



Fresh char isn’t just dry, it’s hydro­phobic. It actually resists water penetra­tion. Residues of tar and resin left in the char are oily hydrocarbons that repel water. Until thin films and beads of tar are etched out of char, it won’t accept water.



However, char left lying on soil a few months loses those black beads of resin, and its color shifts from sparkly black to lusterless gray. Microbes inhabiting char see those hydrocarbon residues as food. Carbon chains and rings contain elec­trons and energy, so bacteria and other organisms eat it like candy.



Without water, char is very dusty. Fresh char is weak, brittle and shatters easily. Dry char easily sheds fine black dust that hovers around like a dark cloud. This dust is hard to handle, easily air­borne, not healthy to inhale, and blows away in the wind. And yet, that very fine dust is the most precious portion to add to soil and transform its structure because it most widely and intimately inserts itself between soil particles.



In normal production, water is used to kill the fire that makes the char — to cool it down and stop the charcoal fire. People beginning to make char are surprised how much water is needed to extinguish a charcoal fire. A lot of heat is held in char, and char’s micropores soak up lots of water. Often engineers quench fresh, hot char by dumping it in water. However, too much water yields char that is soggy, sticky and heavy, which makes handling messy, and screening for particle size difficult. And waterlogged char is anaerobic, and creates a poor habitat for beneficial microbes.



But, with careful attention and proper protocol, a minimum of water will put out a fire, yielding lightweight char that’s easy to process. With the right moisture, char isn’t dusty, but cohesive enough to hold together in soft clumps that are easy and safe to handle and don’t disappear in a wind. And with just enough water, char is suitable media for strong colonies of microbes and earthworms are attracted to it. MICRONIZE

Smaller particles disappear into soil quicker, mixing more thoroughly and in­timately with soil particles and organisms. Thus, crushing, grinding and screening char are valuable to increase char’s dis­persal throughout soil and optimize its effects on soil structure, ion adsorption and microbial colonization.



The first benefit of smaller particle size is increased surface area. For water ions and microbes to penetrate char, they must enter at an exterior surface. Smaller bits have more total surface available for absorption and adsorption. A one-inch chunk has a surface area of — at best — six square inches. The same chunk shat­tered in a thousand fragments has thou­sands times more surface area. Due to extremely fine microporosity, one gram of biochar has over 4,000 square feet of surface area, and 12,000 is achievable. Water, nutrients and microbes quickly penetrate smaller particles and access in­terior spaces.



Smaller particle sizes also distribute in soil more widely, more intimately. Dust — the smallest particle, smaller than most soil particles — inserts itself between soil particles. Carbon isolates soil granules, insulating their electric charges. Thus, clay is less sticky, while sand has more cohesive body.



Smaller particles hold water better, because water penetrates more easily and quickly into char’s sponge-like micro­pores. Large chunks of char have dif­ficulty drawing water into their deepest recesses, and do so slowly.



Similarly, smaller particles allow ions better penetration into the char’s sponge-like internal micropore matrix. A large chunk of char has difficulty drawing ions into its deepest interior spaces.

Rice grain kernels of char are large enough to house thou­sands of microbes. A one-inch chunk of char is a microbial metropolis — millions of denizens inhabit and share such a charred carbon matrix.



Because char performs an assortment of services to soil, a variety of particle sizes seems to work best. Rice-grain size char is large enough for large microbial communities. Powdered char provides condominiums for microbes. Fine dust is most effective to separate soil particles and shift soil structure and tilth.

One advantage of weedy biomass is its char easily crushes to dust in your hand. Minimal effort and machinery is needed to create extra fine, fluffy char, and such char seems to further enhance soil struc­ture and boost its cation-exchange capac­ity (CEC) and anion-exchange capacity (AEC). MINERALIZE

The third step is to add minerals to biochar. Soil is a battery that stores elec­tric charge. Electrons and ions are electric charges that adsorp onto soil particles, es­pecially SOM and biochar. The ability of soils to capture and hold these charges — both positive (CEC) and negative (AEC) — creates a fundamental electric storage capacity — like the electric potential, or ampere-hours, of a battery. Beyond simple quantity, it’s important to also examine how soils can easily and quickly make these electric charges available to organisms.



Both SOM and biochar have remark­able capacity to gather and store both negative (electron) and positive (proton = H+) charges, and are highly efficient to hold and deliver ionized minerals and their electrons to cells.



Biochar’s high adsorption capacity makes it an ideal delivery system for min­erals and their electric charges. Electrons and ions adsorped onto and into biochar are safely, efficiently placed in the root zone, and kept there, ready for ion ex­changes with plant roots. Char-adsorped minerals are removed from the soil solu­tion, and thus have minimal mobility to leach and outgas. So, any electrons in char are kept in the root zone, in locations that attract plant roots.



Micronized minerals that are finely powdered are more able to blend into intimate contact with bits of char, and thus deliver electric charges where they are needed. Like micronized char, smaller particles mean greater surface area and faster, easier digestion by microbes. Stone meal or rock dusts are natural, insoluble forms of minerals that can be mixed with char to charge the soil battery. Synthetic soluble commercial fertilizers can also be micronized to blend into char to supply electric charge.

Most farm soils have deficits and/or imbalances of major minerals, and thus require amendments. Similarly, char made from biomass grown in mineral-deficient soil will be short of essential elements. Any soil test quickly, cheaply reveals what minerals are needed by soil, and in what amounts. Adding these min­erals to soil directly can create losses and lower effective use of the minerals. But blending these minerals with biochar adds needed nutrients in a high efficien­cy, targeted delivery system. MICROBIAL INOCULATION

The fourth step to prepare biochar for soil is to add life to it. With water, nutri­ent ions and vast, empty micropores in the char, microbes move in. We don’t eat our houses, and microbes don’t eat char. They live in it.



In the paradigm shift from 20th centu­ry chemistry to 21st century biology, the culture and care of symbiotic organisms is crucial for soil fertility. For endless eons of geological evolution, microbes man­aged and improved soil to sustain fertility. Creating fertile soil is a fundamental job description for these “no-see-ums” of soil. These least and smallest of all life forms are among the Earth’s most ancient com­munities. Yet, we ignore what we can’t see — microbes — and focus on obvious, visible bulk ingredients — organic matter, compost and mineral fertilizers.



Bacteria are Earth’s oldest life-forms. While a single bacteria is simple, as a collective community or culture, they are complex, and more intelligent than plants. One expression of this is that it is primarily bacteria that consume trace elements and build them into complex biomolecules that perform key, often fundamental, metabolic and regulatory functions. If minerals are the foundation of biology, microbes are the sill plate — where foundation meets superstructure. Microbes transform minerals into pro­toplasm in living cells. Bacteria are the primary consumers of mineral nutrients. They also synthesize critical biomolecules that more complex organisms require. For example, all B vitamins are synthe­sized by microbes, who then supply them to plants and animals.

Click here to read the full article at Acres U.S.A.'s Ecofarmingdaily.com.



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