#207Biochar
207⸱AConcept
- Improves soil structure and organic matter
- Improves plant nutrition
- Increases the coffee yield
Biochar is used to improve soil fertility. It can be produced from any carbon-based feedstock, e. g. crop residues such as coffee husks, wood, rice hulls, etc.
The plant-based feedstock is converted into biochar by heating it up to ca. 500°C with little or no oxygen. This process is called pyrolysis. During this process, the contained cellulose, lignin, and other materials are transformed into gases, liquid (bio-oil), and a solid material called biochar. Biochar consists of carbon and mineral nutrients. The carbon in biochar is much more stable than in the original biomass and does not decompose easily.
Applied to the soil, biochar serves as a soil conditioner. It rapidly improves soil quality and fertility, especially in soils that have a low water retention capacity, such as sandy soils. Why is that so? Biochar is a porous material that can retain water and air. The biochar surface features a high cationic exchange capacity that is able to store plant nutrients such as NH₄⁺, K⁺, Ca²⁺, etc., and to gradually release them to the soil and plants. Areas with low rainfall or nutrient-poor soils will therefore most likely benefit the most from the addition of biochar.
207⸱BTo be considered
There are different ways to produce biochar from artisanal to high technology pyrolysis machines:
In a pit in the ground: This is the most basic way to produce biochar. Wood and other heavier plant-based feedstock can be applied. Light materials such as coffee husks or rice hulls should not be used as they would burn to ashes very quickly and uncontrolled here.
In a kon-tiki: This is a cone-shaped container made of metal that facilitates the handling. Here also, wood and other heavier plant-based feedstock can be applied.
In a pyrolyzer: This is an “oven”, that permits a more controlled process and the use of lighter and less dense materials such as coffee husks or rice hulls.
Biochar improves soil quality and fertility but usually it does not contain enough and balanced nutrients by itself. Therefore, it is recommended mixing it with fertilizers such as Bokashi. A mixture ratio is recommended in the application recipe below. Generally, it is recommended to perform a soil analysis before applying any fertilizers. This provides information about the amounts of nutrients needed.
Biochar can also be used to improve the process of producing compost as a soil fertilizer. See Compost.
Timing: The production takes around 2 days, depending on the amount and number of pyrolysis repetitions and the used technique.
The use of biochar as a soil conditioner requires some patience. There might be an initial “neutral” year. However, a single biochar application has been observed to provide benefits for crop nutrition for several years afterwards. First improvements of soil quality will be seen in the second year after application. Usually, it further improves with biochar aging in the soil which leads to increasing crop yields over time.
207⸱CImplementation
Most common in Brazil is the basic way, using a pit in the ground and coffee wood for the pyrolysis process. However, we invite you to review other forms of pyrolysis used, for example, in Honduras and Guatemala.
Storage
The biochar can be stored in a storage room in big bags, raffia sacks, or plastic boxes with a lid. As it is a very stable product, it doesn’t require high-maintenance storage.
It can be stored for 1 to 2 years before applying it.
207⸱DEconomic benefits
Lower fertilizer costs
This tool allows for a lower demand for synthetic fertilizers and therefore saves input costs over time.
Higher coffee yield
The effects of this tool can lead to a higher coffee yield and therefore a higher income.
Re-use of waste
The economic potential is particularly high if the waste products that serve as tool ingredients are produced on the farm or in the neighborhood, for example, manure from own cattle, straw or wood from the own field. Furthermore, by utilizing waste, this tool helps reduce landfill fees.
207⸱EGreen benefits
Less synthetic fertilizers needed
This tool reduces the need for syntheticfertilizers. This reduces carbon emissions and water pollution, improves soil life, and saves resources.
Re-use of waste
Reusing organic waste material in a circular economy saves resources from being discarded. This reduces the environmental load, carbon emissions, and water pollution.
Carbon storage
This tool removes CO₂ from the air and stores it. This helps to reduce CO₂ levels in the atmosphere.