Biochar is a charcoal-like material made by burning forestry or agricultural wastes in the absence of oxygen. The process of manufacturing biochar is called pyrolysis. In the absence of oxygen, organic matter burns slowly without releasing the contaminating fumes and stored carbon during the process. Due to the lack of oxygen involved in pyrolysis, we are left with hard, porous black, carbon-rich material rather than the soft white ash that we get with an oxygen-rich burn. Biochar is lightweight, similar in appearance to ordinary coal, and is an environmentally friendly material that is mostly carbon. Biochar can be bought commercially, but the best part about biochar is that you can easily make it yourself using your waste twigs and wood.
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Applications of Biochar
Biochar is a healthy soil conditioner that improves the physical as well as chemical properties of the soil. It helps soil in two ways; its physical presence will help to increase the porosity and water holding capabilities of the soil, while its nutrient properties will leach into the surrounding soils and improve their ability to sustain and nourish plant material. Biochar will also increase the soil pH, and biochar will contribute Nitrogen, Phosphorous, Potassium, Magnesium, and Calcium.
Biochar works best with the inorganic fertilizer as it absorbs the nutrients first from the soil. Recently, it has been found that biochar improves the microbial life of soil as well (NAJAR, GANIE, & Tahir, 2015). When soil’s physical, chemical, and biological life improves, water retention capacity also improves. The pore size of biochar is also important as bigger pores will retain water for longer time periods (Guo, 2020).
Slash-and Char instead of Slash-and Burn is a comparatively better technique adopted in Brazil to get the better crop yield, protect the Amazon basin from deforestation, and reduce carbon dioxide emission. Slash-and Char has the ability to retain more than 50% of the organic carbon from the organic materials into the soil, while slash-and-burn retains only 3%. It slowly releases the nutrients creating a long-term and beneficial investment for the farmers (Lehmann et al., 2002).
Far too often, vast piles of hard to dispose of branches, twigs, bark, and leaves are burned in open pile fires to dispose of the material perceived as waste when land is cleared, and trees are cut. By implementing a system for instead creating biochar from this “waste material,” we can store carbon instead of releasing it into the atmosphere. Then we can blend it into the existing soils, dramatically increasing future crop yields.
The burning of fossil fuels releases a tremendous amount of carbon dioxide that eventually becomes the source of global warming. Biochar manufacturing also releases carbon dioxide; however, less than half as much when compared to fossil fuels, and the remaining carbon becomes indefinitely stable. It sequesters carbon for hundreds of years. Climate change experts report that the continuous use of biochar could decrease the carbon dioxide, nitrogen oxides, and methane emissions up to 1.8 billion tons (Abagandura, Chintala, Sandhu, Kumar, & Schumacher, 2019).
An Australian farmer has reported that biochar mixed with molasses can be used as livestock fodder. He claims it improves metabolism and milk production with reduced odor and has no negative impact on the health of animals. Please use caution and start very slowly when experimenting with alternate uses of biochar. As with any new process, great care and patience should be exercised.
How to use biochar in your garden?
Charge Your Biochar
Charging the biochar simply means that by mixing biochar with organic compost, the biochar will soak in some of the nutrients from the compost and make it ready for the soil. This is beneficial because biochar is so porous and absorptive on its own that it will pull nutrients out of the soil at first. By charging it with compost, you allow the biochar to charge itself with nutrients from the compost rather than the topsoil. By doing this first, you can alleviate the short-term adverse nutritional effects that pure biochar will have on garden soil.
An excellent charging mix is to use half biochar and half compost, mix it and allow it to sit for ten days or so before adding it to your planting soil.
Be aware that biochar can be hot and flammable for a long time, even if it is cool to the touch on the outside. Experts suggest wetting your biochar when removed from the cooker and never storing it indoors or near any flamables.
Seeding your soil with biochar is a great way to guarantee that the coming generations will have clean air and healthy soils.
You can apply biochar in the following three ways:
- Topdressing: as the term indicates, you simply lay down a layer of your biochar and compost mix and wet it down.
- Tilling: with the help of a tiller machine, you can easily till in the compost and biochar mixture as you would any other soil amendment.
- Soil Mix: in the case of containers and pot plantings, you can simply blend the biochar mix you’re your planting soil and use it as you would any other planting medium.
Why do we use biochar in home gardens?
- Non-Toxic: increased carbon sequestration decreases its concentration in the atmosphere. Biochar will help our environment, and it sequesters carbon and releases it very slowly compared with the other organic fertilizers, thus reducing the greenhouse effect.
- Improves Plant’s Growth: the structure of biochar is the actual nutrient holder. It was a living tissue that got burned, so it contains carbon and magnesium, nitrogen, calcium, and other minor nutrients.
- Habitat for the Soil Biota: Biochar is manufactured by a process known as pyrolysis. This creates many microscopic spaces in the structure of the charcoal-like material, which provides a very favorable environment for the soil microbes to thrive.
- Buffer for the Soil: Biochar effectively reduces the toxicity of heavy metals present in the ground. A scientific study reveals that the green bean plants grown in biochar-amended soil did not show the heavy metal toxicity (lead, arsenic, cadmium, mercury, etc.) compared to the plants grown in non-amended soils (Prapagdee, Piyatiratitivorakul, Petsom, Tawinteung, & Pollution, 2014).
FAQs Related to Biochar
Question: How can I make my own biochar?
Answer: To make the perfect biochar, sources will tell you that you should build an outer drum with high and low holes and then insert an inner drum into it with low holes. Fill the inner drum with twigs, branches, and wood debris, cap the inner drum, fill the areas between the two with wood to burn. Light the entire top and edges above the drum and then cap it with the drum lid with a chimney. This lets the outer drum burn and heat the inner drum to create biochar but not burn.
In reality, you can create some form of biochar without all of the contraptions by simply creating a hole in the ground or using a drum and placing wood in it to start it burning and then lay on layers as it begins to charcoal. Add more and more layers as the burn progresses. The idea is to snuff out the oxygen from the lower layers before they entirely burn and turn to ash. Once your hole is full of slowly smoldering wood and the top is starting to look like charcoal, douse it with water to put it out, let it sit for a day or two, dig it out, mix it with aged compost and let it sit for ten days or so.
Any biochar-making process will take some time to perfect, and you are sure to make some ashes in the process, but stick with it, and you will come up with a process that works for you.
Question: Is making biochar dangerous?
Answer: Making biochar is essentially playing with fire, so yes, it is potentially very dangerous. If you create a biochar cooker out of drums, the steel will get very hot and dangerous. The flames and sparks from biochgar making can certainly start houses, grasses, trees, and any flammable matter on fire. You must always use caution to only create biochar in areas where there are no dry materials to catch fire and always keep ample water available to quench your fire.
Question: How much biochar will be good annually?
Answer: This all depends on your soil. You could plant right into your compost and biochar mix, so it is not a problem. Be aware that it is essential to mix the compost and biochar and let it sit for at least ten days. You will see good results if you make a 50/50 mix of compost and biochar and then mix that at about 20% bichar mix/80 soil. There is really no need to be so precise, just spread your mix over the ground and blend it in. Adding more mix year after year is also a good practice.
Question: Is biochar good for the garden soil?
Answer: Biochar is absolutely good for garden soil. Adding this to your already established gardens will improve yields. Using biochar in any soil can help you create a vibrant, nutrition-filled garden almost anywhere.
Question: What is the difference between Biochar and Compost?
Answer: Biochar is made under controlled conditions by heating and essentially cooking the moisture out of plant-based products to produce the charcoal-like substance. Compost is simply organic matter mixed together over time and allowed to begin to decompose naturally. Biochar mixed with compost is your best option. Both get better with age. Fresh biochar can pull nutrients away from plants, and fresh compost can be too rich and can burn plants. A nice mixture of both that is well-aged is always best.
Abagandura, G. O., Chintala, R., Sandhu, S. S., Kumar, S., & Schumacher, T. E. J. J. o. E. Q. (2019). Effects of biochar and manure applications on soil carbon dioxide, methane, and nitrous oxide fluxes from two different soils. (6), 1664-1674.
Guo, M. J. S. S. (2020). The 3R principles for applying biochar to improve soil health. 4(1), 9.
Lehmann, J., da Silva Jr, J. P., Rondon, M., Cravo, M. d. S., Greenwood, J., Nehls, T., . . . Glaser, B. (2002). Slash-and-char-a feasible alternative for soil fertility management in the central Amazon. Paper presented at the Proceedings of the 17th World Congress of Soil Science.
NAJAR, G. R., GANIE, M. A., & Tahir, A. J. P. (2015). Biochar for sustainable soil health: a review of prospects and concerns. 25(5), 639-653.
Prapagdee, S., Piyatiratitivorakul, S., Petsom, A., Tawinteung, N. J. W., Air, & Pollution, S. (2014). Application of biochar for enhancing cadmium and zinc phytostabilization in Vigna radiata L. cultivation. 225(12), 1-13.