Nelson Bays Mycorrhizas www.mycorrhizas.co.nz

Several ancient civilizations traditionally practiced modifying their garden soils by applying charcoal into compost & or soils.  

 

In Brazil, the Portuguese name for ancient pre-Columbian human made soils found in Amazonian Forest is "Terra Preta de Indio", or in English known as "Amazonian Dark Earths". In Aotearoa New Zealand, traditional man-made & charcoal amended soils were known in te Reo Māori as "para umu" soils. " "Biochar" is a modern word to describe charcoal used as a soil amendment. "Anthrosols' is the scientific name for 'man-made' soils.

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Our soil ecological consultancy services are focused on plant biology, mycorrhizal symbioses & on the unintended environmental consequences of intensive soil disturbance and prolonged vegetation clearance. Our advisory services can provide growers with valuable insights into the natural and human-made processes that either accumulate or else degrade soil carbon levels. We can also provide expert consultancy services regarding the relative benefits & deficits of a range of different biochar production conditions, biochar application rates, & make comparisons of various methods used to apply biochar into soils & or composts.

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At the invitation of CRC Press, an international publisher, Nelson Bays Mycorrhizas provided a book chapter that reviewed and compared methods to apply biochar into soils, see "Biochar and Soil Biota" (2013)

• https://www.crcpress.com/Biochar-and-Soil-Biota/Ladygina-Rineau/p/book/9781466576483  

Recently this work has since been cited several times by authors in "Biochar in European Soils and Agriculture - Science & Practice"  (2016)

• https://books.google.co.uk/books/about/Biochar_in_European_Soils_and_Agricultur.html?id=zlaaCwAAQBAJ

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What is Charcoal 'pyrolysis' & 'gasification'?

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Charcoal is most commonly used as a solid fuel for grill cooking on bar-b-cues. Charcoal can be formed naturally as the cooled embers resulting from  partially-burned wood formed during forest fires, & or as the 'charred' or blackened leftovers in a domestic fireplace or bonfire. However, this naturally charred by-products of fires also retain oily gums & acrid smoke or creosote smelling volatile residues that are additional fuels to the solid charcoal.

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The practice of smelting of metal ores from rocks, & thus the beginning of the 'Iron Age' & 'Bronze Age' was initially made possible by the making and burning of charcoal which can produce much higher temperatures than available by burning wood or coal. Humans have since learned that the ideal conditions for making charcoal from wood is achieved by using kilns to cook or heat wood whilst avoiding burning to ash by the reduced availability or the absence of oxygen. 

 

"Pyrolysis' is a scientific name for the use of heat ("pyro" = heat) to  'boil off', 'distilll' or 'gasify' water & flamable gases (i.e. renewable fuels) from wood (or coal) to produce charcoal plus  'woodgas' or 'syngas'; or else with coal to produce 'coke' plus 'coal gas' or 'producer gas'.  

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Charcoal produced at about 350 degrees celsius is ideal as BBQ fuel or for smelting metal ores. The liquid gums of resins that remain in charcoal made at these temperatures can also supply bio-degradable food sources for soil bacteria & a number of soil fungi that are decomposers.

 

However, despite common misconceptions not all fungi are decomposers & or plant pathogens, in fact the common plant root symbionts, which are also the most ancient of all mycorrhizal fungi types, i.e. arbuscular mycorrhizal fungi (AMF), in fact are dependant on becoming partners with living plant hosts & can not use simple carbon sources h as sugars, nor more complex Carbon compounds found in soil organic matter or from dead organisms 

 

Charcoal can also be produced at higher temperatures, (e.g. between 650 to 1,000 degrees celsius), resulting in more volatile gases being boiled off, no residual smells or tastes, & an enlarged surface area of the charcoal. This large 'surface area' effect results in an increased ability for charcoal to bind onto a variety of chemicals & agricultural waste products including urine, ammonia, compost leachate, animal manures & soluble NPK fertilizers. It is helpful compare how Charcoal surfaces attract stuff in a similar manner to how 'Velcro' attracts fluff.

 

The Carbon Cycle: - Carbon Source & Sinks

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All living oranisms are made of carbon. Respiration occurs when aerobic organisms breath in oxygen in order to oxidise & obtain energy from carbon from their food, carbon dioxide is a by-product breathed out into the atmosphere. Dissolved carbon dioxide can be found in lakes & oceans, Carbon can also be found as fossilized rocks including limestone, & as fossil fuels including coal, crude oil, & methane gas (CH4).

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The living & non-living components of Earth are always changing, the levels of Carbon it Earth's atmosphere, oceans, rocks, & soils is dynamic, Carbon moves between living & non-living systems & does not stay still.

 

Over 1,000s of millions of years, the Oxygen levels in Earth's atmosphere has all been biologically produced, at first by ancient unicellular cyanobacteria, & later by plants, algae, lichens, & mosses containing chloroplasts using photosynthesis to combine carbon dioxide and sunlight to make their own food and grow. The carbon from CO2 becomes part of the plant.

 

Animals eat living plants & micro-organisms may consume decomposing plants & other organisms in order to obtain food and obtain energy-rich Carbon & other mineral nutrients. Plants that die and are buried in the absense of oxygen may over millions of years eventually turn into carbon-rich peat soils or fossil fuels. When forests are destroyed by fire, or when humans burn fossil fuels, most of the carbon quickly enters the atmosphere as carbon dioxide.

 

Carbon dioxide and methane are a greenhouse gases (GHGs) that  trap heat in the atmosphere. Without greenhouse gases, Earth would be a frozen world. Since the indistrial revolution which began in the late 1700s, humans have burned so much wood & fossil fuels that there is now about 30% more carbon dioxide in the air today than there was about 150 years ago. Dissolved carbon dioxide is acidifying our oceans & lakes. In crop soils that have been ploughed or rotary hoed, bare soil surfaces increase the oxidation of carbon held soil organic matter, further increasing levels of atmospheric carbon dioxide. Earth is becoming a warmer place.

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Biochar - "closing the loop"

Microscopic examinations of ancient naturally occuring charcoal found in soils, & likewise 3,000 year old charcoal found in man-made Amazonian dark earths (i.e. biochar) was found to be very resistant to demposition, & thus was prevented from returning to atmospheric carbon dioxide.  

  

Biochar offers humans unique opportunities to alter the physical & biological properties of soil, whilst reducing atmospheric carbon dioxide from the atmosphere & oceans, by locking up or 'sequestering' renewable sources carbon in soils for 1,000s of years ,