Biochar production is modeled after a process begun thousands of years ago in the Amazon Basin, where islands of rich, fertile soils called terra preta (“dark earth”) were created by indigenous people. Anthropologists speculate that cooking fires and kitchen middens along with deliberate placing of charcoal in soil resulted in soils with high fertility and carbon content, often containing shards of broken pottery. These soils continue to “hold” carbon today and remain so nutrient rich that they have been dug up and sold as potting soil in Brazilian markets.
Soil’s Best Friend— Because of biochar’s physical and chemical nature, it has a unique ability for attracting and holding moisture, nutrients, and agrochemicals even retaining difficult to hold nutrients like nitrogen and phosphorous. Nitrogen tends to run-off regular soils, upsetting ecosystem balance in streams and riparian areas. Biochar also holds gasses; recent research has proven biochar-enriched soils reduce carbon dioxide (CO2) and nitrous oxide (NO2) emissions by 50-80%. NO2 is a significant greenhouse gas, 310 times more potent than CO2.
Biochar’s immense surface area and complex pore structure (a single gram can have a surface area of over 1000 square yards) provides a secure habitat for micro-organisms and fungi. Certain fungi form a symbiotic relationship with plant root fibers and this allows for greater nutrient uptake by plants. There is speculation that this fungi may play a part in terra preta’s ability to regenerate itself.
Persistency in Soil— It is undisputed that biochar is more persistent than any form of organic matter commonly applied to soil. Because of biochar’s long-term persistence in soil (more than 2,500 years and counting), all the associated benefits of nutrient retention, water retention and overall soil fertility are longer lasting than with common fertilizers alone. Biochar, comparitively inert, doesn’t break down like other organic soil amendments and resists chemical and microbial degradation, especially when buried.
Biochar reduces soil acidity decreasing liming needs but does not actually add nutrients. Biochar made from manure is the exception; it retains a significant amount of nutrients from its source. Because biochar attracts and holds soil nutrients, it reduces fertilizer requirements – something common organic matter cannot do. As a result, fertilization costs are minimized and fertilizer (organic or chemical) is retained in the soil for far longer. Chemical fertilizers are typically fossil-fuel based, thus biochar provides additional indirect climate change benefits by reducing fertilizer needs.
Enhanced Crop Yields— When added to soil, biochar improves plant growth and enhances crop yields, increasing food production and sustainability in areas with depleted soils, limited organic resources, insufficient water and/or access to agrochemical fertilizers. Not all soils react the same to biochar and it frequently can take up to a year to see results. On poor soils with low carbon content, many studies have shown biochar can increase crop yields up to four times.
Biochar enhances soils. By converting agricultural waste into a powerful soil enhancer that holds carbon and makes soils more fertile, we can boost food security, discourage deforestation and preserve cropland diversity.
Increased number of beneficial soil microbes especially mycorrhizae
Increased water retention
Increased cation-exchange capacity resulting in improved soil fertility
Moderating of soil acidity
Reduced leaching of nutrients
Possible reduced emissions of nitrous oxide