I'll answer the last question first. I do not claim to be an expert in the science of biochar. I can tell you what I've learned about it, and I can show you my results in using it as I proceed in my various experiments. I feel that I have found some interesting things in which I have found little information about when they are combined in biochar. I have said before in my videos and blogs that I'm not strong on original thinking, but I'm very good at stringing together ideas from different information sources. I will be writing multi-part blogs about biochar. I'll include my findings about compost tea and biochar since they seem to work well together.
The term “biochar” is formed from two words, “biological” and “charcoal.” Biochar is a specific use for charcoal, in that it can be used as a soil amendment, a possible replacement for hydroponic media, or with some modification, actually provide some nutrition to the plants. There are many scholarly and scientific articles and studies about the 'miracle' of biochar -it has become the thing 'du jour' for many growers and gardeners. It is an ancient discovery still in use around the world with new research providing insights into why and how it works.
There is another term related to biochar: Terra preta. Terra preta is a Portugeuse term meaning 'black earth.' In general terms, it describes a dark black or brown, thick and rich humus which is found in the Amazon rain forest and other tropical and sub tropical areas of the world. The washing out, or leaching of nutrients in tropical and sub tropical soils is a huge agricultural issue. Biochar, among its many features, can help prevent leaching of nutrients from soils.
The early Amazon peoples, and other people around the world, discovered that by burning wood, bones, clay pots, leaves, grasses, animal hides, dung, urine and other nutrient-rich things together created a very rich soil when it decomposed. This was usually done by digging a shallow pit, setting fire to the debris, and covering the pit in some manner as to restrict most oxygen. This allowed for the partial combustion, or pyrolysis, of the material resulting in a low-ash charcoal. This was a low-heat biochar, so many nutrients were retained.
Biochar offers four major and desirable qualities: 1. Biochar can lock up, or 'sequester' carbon, such as excess carbon dioxide, out of the environment and put it back into the soil, nutrient solution, or a product for re-use. 2. Millions of microscopic pits and spaces are formed in and on the charcoal, almost like a sponge, significantly increasing surface area. These spaces and pits store and return nutrients, moisture and gases to the roots, through a process called 'cation (cat-eye-on) exchange capacity, or CEC.' These pits also provide 'shelters' for microbes and fungi. 3. Biochar can replace bulking media, such as perlite, vermiculite, peat moss, gravel, clay pellets, sand, and other expensive, hard-to-get and environmentally challenging amendments. 4. Waste and by-products such as nut shells, grass clippings, and other things are reused and recycled in biochar.
There are many types of biochar. The electrochemical properties (CEC), or how the charged atoms, also known as ions- of the needed elements attach to and release from the biochar, are dependent on the type of combustible organics used as feedstock (hardwood, softwood, grasses, hulls, etc.), the temperature at which the char is made, and oxygen contact. These choices and the CEC affect the pH of the finished charcoal, with most chars running in the 7.8 to 8.5 pH range. This isn't necessarily a bad thing: most soils and hydroponic systems tend to be acidic, so biochar can work to “sweeten” things up to a more manageable 5.8 to 7.2 pH. There are also ways to chemically pretreat the feedstock to soften (remove lignin and hemicellulose) and to acidify it, creating a somewhat lower pH char. I used some ideas from non-agricultural industries to figure out my own method of delignifying and acidifying my biochar, which I will discuss in future blogs.
Biochar made at higher temperatures, with methods that strictly control oxygen, will create hydrocarbon fluids that can be catalyzed into biodiesel and plastics. My son and I created some primitive biochar-derived plastics experimentally for homeschool. It cost us almost nothing but a few hours of time. It is a relatively straightforward concept that has been shown to work ranging from inexpensive home-grown distillation setups used by some to run their diesel cars and machinery to large multi-million dollar facilities which produce biodiesel and marketable plastic products. I will be experimenting in this area sometime in the future but I am concentrating on food production with low-temperature biochar at this time.
In this Part 1 of my biochar blog, I gave you a very general description of what constitutes biochar and how it works. Future blogs will give specific information about my experiments and discoveries and I will address why growers, big and small, should embrace biochar for better plant growth and to help the environment. I will be adding several growing experiments videos to my Plain 2 Grow Jim You Tube channel soon!