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What is Biochar?
Biochar is one of the oldest soil amendments. A soil amendment is a product that when properly applied improves soil quality and fertility. Biochar is essentially charcoal that is produced in a special way from heating the air-dried plant material (biomass) in an oxygen depleted environment. The longevity of biochar in the soil environment and its effectiveness as a soil conditioner is directly influenced by the way it is produced.
Biochar is primarily a plant based product that has agronomic and industrial applications. When prepared properly, biochar can improve the quality and fertility of soil and increase yield. A properly produced biochar is safe to use in organic food production. To be devoid of contaminants, biochar is normally produced from air-dried biomass between 400 to 600 degrees Celsius (752-1112 degrees Fahrenheit).
The research on biochar at Lincoln University was started in 2011 under the supervision of Dr. Raymond Bayan. Now LU is recognized as a center of biochar research and production in Missouri. The biochar produced at LU is through the slow pyrolysis that results in more biochar and adequate combustible gases. The syngas is sustainably used in biochar production. Lincoln University has provided information about safe production and application of biochar to farmers, entrepreneurs and the public.
How does biochar work in the soil environment?
During the past few years, biochar has been the focus of many scientific investigations. From what we know:
- All biochars that are produced through the slow pyrolysis include some nutrients immediately after their production. Normally, herbaceous biochars include more nitrogen than the ligneous biochars. The nutrient content of biochars, however, is not enough to sustain plant's optimal growth during it life cycle (Bayan, 2014ab). Therefore, biochar is not considered to be a fertilizer.
- All biochars contain some mineral matter (ash). The pH of water-saturated samples of all biochars produced through the slow pyrolysis from biomass that is available in Missouri is in the alkaline range (Bayan, 2014ab). This alkaline pH helps increase nutrient availability in low pH soils.
- All biochars have a higher specific surface area than their biomass precursors. The pores in biochar retain water and nutrients and provide optimal conditions for beneficial microorganisms to grow especially when biochar comes into contact with growing roots. The pore volume of biochar is affected by the way it is produced (Bayan et al., 2014).
- All biochars have surface charges at lower pH values that make them capable of retaining certain nutrients such as potassium, calcium, magnesium, etc. (Bayan, et al., 2014).
- All biochars are capable of retaining water in their cavities. This can help plants cope with adverse effects of drought when grown on a soil that is treated with biochar (Joseph, et al, 2009).
- Biochars do not denature soil enzymes and do not reduce soil enzyme activity in the long-run; therefore, biochars do not have a negative effect on nutrient cycling in the soil environment (Bayan, 2013b).
- Biochars are capable of retaining some nutrients preventing them to be lost to moving water or air in the soil environment. This may reduce fertilizer use to achieve maximum yield.
Preparation for application
How to Apply Biochar to Soil
Biochar should be mixed with the top 15 - 20 cm (6 - 8 inches) of soil. To maximize its amending effects, biochar should not be broadcast over the soil; it should be tilled or disked into the soil.
Spot Application of Biochar
Biochar can be applied to a 4 ft2 area of soil before transplantation or seeding. Use a spade or shovel to remove soil from a 4 ft2 area to a depth of 6- to 8-inch and transfer the soil into a wheelbarrow. Mix biochar (3.5 lbs) with the soil in the wheelbarrow thoroughly before backfilling the pit with the soil mixture from the wheelbarrow.
Other uses of Biochar
In recent years biochar has been used for purposes other than a soil amendment. In addition to its agronomic values, scientists and engineers are finding novel values for biochar. For example, biochar is now being used in poultry industry as a disease and odor control agent and livestock farming as a feed supplement, and in metalworking as a reducing agent. Biochar is being used to clean water and to absorb odor. It is used in batteries and as building material. A Swiss biochar scientist, Dr. Hans-Peter Schmidt (2014) has found "55 uses for biochar and counting."
The economic relevancy of biochar system
What is a biochar system?
A biochar system is based on the use of biochar in agriculture and industry for cost effective production and to promote sustainable use of resources while safeguarding the environment (Lehmann and Joseph, 2009).
Can a biochar system contribute to economic growth?
The biochar system can lead to economic growth if biochar itself is produced sustainably as a co-product of the bioenergy production from the biomass. Therefore, ideally biochar production should be seen as part of a larger design that includes biochar as one of its products but not the sole product. As biochar finds more uses in agriculture and industry, its value will increase. The biochar industry, however, will succeed when biochar systems are custom tailored for a region based on region's specific needs and biochar is produced sustainably as a carbon negative practice.
What is a carbon negative practice?
When the biomass (e.g. in the swamps) were buried due to cataclysmic events in the past history of planet Earth, the nature practiced a carbon negative act! The carbon from the atmosphere was sequestered through photosynthesis and, as an essential component of biomass, was buried in the earth for good. Although biochar properties are completely different from those of coal, when biochar is mixed with the topsoil (15 to 20 cm), the carbon is effectively removed from the atmosphere and buried in the soil helping plants grow better. The biochar can persevere in the soil for hundreds of years.
What is a carbon positive practice?
Any practice that involves combustion of carbon that has already been permanently removed from the atmosphere and buried in the earth (such as coal and hydrocarbons) is a carbon positive practice.
What is a carbon neutral practice?
When a tree or parts of it die, the fallen parts disintegrate, decompose and eventually change into carbon dioxide that is returned into the environment. In other words, the carbon that was temporarily removed from the atmosphere by photosynthesis is returned back to the atmosphere in a short span of time. Hence, in the atmospheric carbon budget there is no net change. This is an example of a carbon neutral process. When people burn the wood in their fireplace, they exercise a carbon neutral practice. When biochar is made in a double barrel pyrolyzer as explained above, minimal amount of biomass is combusted to start the pyrolysis process, the combusted biomass here is carbon neutral but the resulting biochar, if mixed with the soil, constitutes a carbon negative practice. A biochar system normally includes all these process but the net result is carbon negative.