Biochar – A Carrier of Hope and Nutrients

What is Biochar and how is it different from charcoal?
You may know charcoal from firing BBQs. Biochar, however, is a special type of charcoal produced by a thermal process called pyrolysis (from the Greek, ‘pyro’, meaning fire and ‘lysis’, meaning separation). During pyrolysis organic matter such as wood waste, organic kitchen waste, rice husks, grass cuttings etc. is thermos-chemically disintegrated in an oxygen-free environment at high temperatures of between 400 °C and 900 °C. Biochar starts out as organic material and becomes more mineral-like with the heating (Wilson K 2014). The carbon sequestration achieved in the process is 489 kg CO2 per 1,000 kg of organic material (Gerber 2009), which means almost half of plant wastes’ total carbon will be permanently stored in the biochar for more than 1,000 years (Schmidt HP 2011). When incorporated into the soil CO2 is actively taken out of our atmosphere, creating a so-called ‘carbon sink’ which is able to slow down climate change.

Hans-Peter Schmidt, a biochar expert, said in an article published in the Ithaka journal (1/2012) (

“The current imbalance in the world’s carbon and nitrogen cycle is not just the main cause of climate change, but also a direct threat to ecosystems through eutrophication, desertification and a decline in biodiversity. Re-balancing through regularly recycling organic material with its carbon, nitrogen and phosphor content is needed. Biochar has the potential to play a key role, as it not only converts the carbon found in a wide range of biomasses into a stable form, but also binds volatile nutrients from biomass residues, thereby recycling them for agricultural use. Though still “early days” for biochar, the prospects for its use are good, whether in crop or livestock farming, or in industry.”

Soil and Biochar
Healthy soil can be pictured as a living being that consists of innumerable small organisms, inorganic minerals, water, roots of plants and organic matter. Almost 90 % of all organisms on our planet are living in the soil (Schmidt HP 2010). Once natural vegetation has been removed microorganisms disappear, the soil slowly loses its natural fertility and gets depleted in nutrients. In order to still be able to grow crops, non-organic farmers add tons and tons of inorganic fertilizer, not knowing that the inorganic fertilizer kills the soil life. In order to compensate for that loss even more inorganic fertilizer is added, at high cost to the farmer and the planet – most of these fertilizers are oil- and gas-based. This is a deadly spiral, which ends in contaminated soil and groundwater often resulting in ‘badlands’ – biodiversity deserts. There is an urgent need to maintain and build healthy, living soils which keep fertility.

Since ancient times it is known that poor soils can be significantly improved by adding biochar. In South America biochar amended soil is known as “terra preta” black soil. Scientific experiments in the Brazilian Amazon have shown that a thousand years after application of the biochar crops still grow better on biochar amended soil than on freshly cleared rainforest soil.

Before applying biochar to the soil it has to be “activated”, meaning it has to be loaded with nutrients and microorganisms, which can e.g. be achieved by mixing it with compost or organic fertilizer. The pyrolysis process creates thousands of microscopic holes in each piece of Biochar. One gram of Biochar could, theoretically, unfold to be the size of a soccer pitch. This extremely high surface area means that lots of microorganisms can colonise the Biochar and later colonise depleted soil; the Biochar also helps soil to retain water.  Once activated/loaded Biochar is mixed into depleted top soil, or simply put on the soil surface as a top dressing ideally covered with mulch. Over time the soil will become more alive, restoring itself and getting back into its healthy natural cycle.

SEM images of the popular bio-char (y sectional surface) after the partial gasification

How does Biochar modify soil?
Biochar serves as a carrier for nutrients, water and habitat for microorganisms, all crucial for a healthy soil and healthy plants. Due to its big sponge-like surface (300 m2 per 1 g) biochar is able to store a five times higher amount of nutrients and water than its own weight (Schmidt HP 2014). All the stored nutrients are easily available for plants.

Key facts about biochar (according to Schmidt HP 2010, 2011, 2012):
• Biochar stores nutrients like nitrogen and prevents them from being washed away
• Stored nutrients are easily available for plants and microorganisms. Through the stimulation of microbial symbiosis, the plant takes up the nutrients from the porous carbon structure.
• Biochar provides habitat for microorganisms, which are crucial in processing nutrients and building new fertile soil
• Plant growth and plant health is improved
• Increase of myccorhiza, so plants can access nutrients more easily
• Biochar improves water retention and stabilizes soils
• Biochar helps to prevent erosion and stagnant moisture and releases water through dry periods
• Biochar improves aeration and reduces emission of climate-wrecking gases like methane or nitrous oxide
• Biochar is capable of binding toxic substances (heavy metal, pesticides, etc) which is not only important for healthy plants but also for clean water and ground water protection
• Biochar is raising the soil’s pH-value, again making nutrients more accessible to plants
• Biochar reduces waste problems by recycling organic materials such as arboricultural waste, old bamboo scaffolding, old palettes, rice husks, coconut fibres, organic kitchen waste and so on – keeping them out of the landfill where they decay and release carbon into the atmosphere.


How is Biochar used in KFBG
Biochar is used in KFBG to improve poor soils for organic farming, gardens and forest restoration. It helps us to reduce and recycle organic wastes.

We have had a small Biochar machine for several years. In July 2015 we have installed a new state-of-the-art machine, custom built in Australia, which has almost no emissions and, as it is the size of a shipping container, can handle a large volume of wood everyday if needed. As we change our abandoned, unproductive mono-crop orchards in the middle areas of KFBG, over the next two decades, we will convert all the cut wood to biochar and put this back onto the old orchard terraces, with mulch to enrich the depleted soil, ready for planting a wide range of native tree seedlings to create a healthy native forest and seed nursery.


Further information and links:
Schmidt HP: Terra Preta – model of a cultural technique

Schmidt HP: Climate Farming – A Master Plan for Sustainable Agriculture

Schmidt HP: Biochar – a key technology for the planet

Wilson K: How biochar works in soil

Gerber H (2009): CO2-Bilanz des Pyregreaktors, Ithaka-Journal 2009,, ISSN 1663-0521

Schmidt HP (2010): Climate Farming – A Master Plan for Sustainable Agriculture, 1/2010, S.314–317,; Publisher: Delinat-Institut für Ökologie und Klimafarming, CH-1974 Arbaz;, ISN 1663-0521

Schmidt HP (2011): Pflanzenkohle, Ithaka Journal 1/2011: 75–82 (2011);; Publisher: Delinat-Institut für Ökologie und Klimafarming, CH-1974 Arbaz;, ISSN 1663-0521

Schmidt HP (2011): Pflanzenkohle – Landwirtschaft als Klimaretter – ein Jahresbericht. Ithaka Journal 1/2011: 9–13 (2011),; Publisher: Delinat-Institut für Ökologie und Klimafarming, CH-1974 Arbaz;,

Schmidt HP (2012): Pflanzenkohle, eine Schlüsseltechnologie zur Schließung der Stoffkreisläufe, Ithaka Journal 1/2012: 75–79 (2012);; Publisher: Delinat-Institut für Ökologie und Klimafarming, CH-1974 Arbaz,, ISSN 1663-0521

Schmidt HP (2014): Terra Preta – model of a cultural technique, the Biochar Journal 2014, Arbaz, Switzerland.
ISSN 2297-1114;

Wilson K (2014): How biochar works in soil, the Biochar Journal 2014, Arbaz, Switzerland. ISSN 2297-1114;