FAQ (frequently asked questions)
General questions
What is biochar, terra preta and biochar compost?
What exactly is the difference between biochar, terra preta and biochar compost?
Biochar is a type of charcoal. However, the name makes it clear that this is pyrolyzed natural wood or trunk wood or pyrolyzed wood-containing green waste. In principle, we reject the use of processed wood for Terra Preta. Processed wood, e.g. from furniture or wooden fences, cladding, etc. used outdoors, can be contaminated with heavy metals and various toxins such as insecticides or fungicides due to impregnation, other types of treatment or varnishing. In the pyrolysis of these woods, particularly dangerous and long-lasting PAHs (polycyclic aromatic hydrocarbons) can be formed, which, among other things, are carcinogenic and harmful to soil organisms and can then in turn be absorbed by plants intended for consumption.
Biochar is very porous, depending on the starting material, because pyrolysis only leaves the carbon skeleton and the ash (mineral components of the starting material). Depending on the starting material and the pyrolysis temperature, it has a very high specific surface area, sometimes exceeding 300 to 450 m² per gram (1). Depending on the material used, the largest surface is reached at pyrolysis temperatures of 650 and 850°C.
In the pyrolysis ovens we used, the PAHs analyzed were below the detection limit (2).
If charged, unpolluted biochar is worked into the soil in the compost, it promotes beneficial soil microorganisms and promotes the build-up of humus. This happens in two ways: On the one hand, the majority of biochar remains in the soil as stable carbon for hundreds of years (3). At an average soil temperature of 10° C in temperate latitudes, 95 percent of the biochar would still be preserved in 100 years. In addition, the degradation of biochar in the soil decreases with increasing residence time in the soil (4).
On the other hand, the large surface - depending on the special characterization of the biochar and the ability to store nutrients and release them again (cation exchange capacity) - has an important function in the formation of humus. It can combine with other particles (clay particles, existing clay-humus complexes and organic components in the soil) and develop into a very fertile and stable soil within a few months. The warmer it is, the faster this conversion takes place.
For the production of Terra Preta, we suggest enriching 10% by volume of biochar with animal manure and thus loading it with nutrients. Uncharged biochar in the soil is not beneficial, because due to the ability of the charcoal particles to bind nutrients to themselves (adsorption capacity), these would initially be withdrawn from the soil and thus from plant growth. It is therefore urgently necessary to charge biochar with nutrients before it is introduced into the soil or used as a valuable additive for soils/substrates.
It has been scientifically proven that biochar in the soil promotes and increases microorganisms and increases plant availability - e.g. of P. The hyphae of soil fungi (mycorrhiza) take nutrients, especially phosphate(P) from the fine pores of the biochar and exchange them with the roots of the plants for absorbed nutrients. Root exudates of the plants, i.e. sugars, hormones, amino acids that they cannot produce themselves. This symbiosis is useful for both the plants and the fungi, because the latter do not carry out photosynthesis and plants are thus supplied with the necessary nutrients better and faster. In addition, reserves of P in the soil are activated by the fungi, so that additional mineral fertilization with P is not necessary.
This way of fertilizing the plants with charged biochar is extremely efficient - approx. 90% of the nutrients (5) reach the plants in this way, because they remain stably bound to the biochar until the soil microorganisms bring them to the plant roots. Pure mineral fertilization can lead to high losses if not used professionally; traditionally, 10 to 40% of nitrogen was scrubbed or released into the air in the form of nitrous oxide. Attempts are currently being made to counteract this through improved practice and legal requirements. Excess organic fertilizers such as liquid manure are also no longer absorbed by plants and are washed out of the soil when it rains and find their way into the groundwater and receiving waters (ditches, streams, rivers) and ultimately into the seas. “If only the arable land is considered in isolation, an average potential nitrate concentration in the seepage water of 112 mg NO3/l is calculated for them. In 18 rural districts, average nitrate concentrations in the seepage water of over 50 mg NO3/l are to be expected as a result of the high nitrogen surpluses (6). Reference is made here to the EU lawsuit against Germany (red areas with nitrate values over 50mg/l groundwater at the corresponding measuring points). In soils with biochar, on the other hand, significantly less nitrate is washed out, which has been proven by meta-studies (7).
Terra Preta do Indio (Portuguese for black earth) is now, strictly speaking, a "product name" of the indigenous peoples of the Amazon region, who were created by human activity well over 1000 years ago. Similar anthropogenic black soils based on biochar are also known in other parts of the world, such as in Africa (Ghana, Sierra Leone, Liberia, Guinea), Southeast Asia (Indonesia) and also in Europe (Germany and Sweden). The active principle and the recipe are very similar, because in all cases people have mixed biochar with animal dung, compostable organic residues, faeces as well as bones, shells - i.e. the respective starting materials - and thus created a particularly fertile black earth. Therefore, to put it simply, we speak of Terra Preta, although it should actually be called "biochar substrate according to the Terra Preta principle".
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1) See: "Biokohle", eds.: P. Qucker, K Weger, Springer Verlag 2016; Chapter 4.4.1 Interface
2) WisBer, Dr. Sebastian Meyer, analysis results of the Chantico biochar, Sept. 2015
3) See: "Biokohle", eds.: P. Qucker, K Weger, Springer Verlag 2016; Chapter 5.3.1. Stability of biochar in soils
4) Wang (2016): GCB Bioenergy 8:512-523, quoted from Bruno Glaser: https://www.geo.fu-berlin.de/geog/fachrichtungen/physgeog/geooekologie/medien/download/Vortraege_Workshop_CarboTIP_2018/7_Stand_Pflanzenkohleforschung_GLASER. pdf
5) Root application of biochar - high yield increase with little biochar by Hans-Peter Schmidt; http://www.ithaka-journal.net/rootapplication
6) Lower Saxony Chamber of Agriculture: NÄHRSTOFFBERICHT FÜR NIEDERSACHSEN - 2018 -2019: Page 53
7) Cai (2017) Soil Science and Plant Nutrition, 63:405-414 in: https://www.geo.fu-berlin.de/geog/fachrichtungen/physgeog/geooekologie/medien/download/Vortraege_Workshop_CarboTIP_2018/7_Stand_Pflanzenkohleforschung_GLASER.pdf
What/who is behind the Terra Preta e.V. association?
What are the goals and projects?
The association mainly consists of members of the Friday for Future and Scientists for Future movements, including gardeners and farmers. This is based on the knowledge that a significant proportion of Germany's greenhouse gases come from factory farming and from conventionally fertilized and cultivated fields. The far more effective greenhouse gases methane and nitrous oxide predominate (8). The Federal Environment Agency (UBA) estimates for 2020 that “around 63% of all methane (CH4) emissions and 81% of nitrous oxide (N2O) emissions in Germany come from agriculture. (...) Carbon dioxide emissions from liming, use as mineral fertilizer in the form of urea and CO2 from other carbon-containing fertilizers make up only a small proportion (4.4%)" (9). According to this, emissions from agriculture (excluding animal husbandry) account for 19.5% of Germany’s climate gases in 2020 (10).
Interestingly, the IPCC working group (11) on land systems also explains that agriculture and animal husbandry in particular could contribute to largely offsetting the around 12 gigatonnes of greenhouse gas emissions from this area. This approach is positive because the polluters are required to neutralize their own emissions.
We go one step further: Humus-based soil management that uses biochar intelligently can also sequester another 5 to 10% of greenhouse gases from the air, i.e. store more carbon in the soil than it emits and thus become a carbon sink. It is currently the only relevant measure by changing the management of agricultural land not only to reduce greenhouse gas emissions and nitrate leaching, but even to achieve negative emissions. Soils therefore harbor potential for counteracting climate change. A side effect is that less energy-intensive mineral or organic fertilizer has to be spread on the land, since biochar prevents nutrients from being washed out and outgassing.
A particularly valuable "side effect" is that biochar compost can increase soil fertility and thus soil life. Since biochar has a very high pH value of up to pH 10 (12), it can also have a stabilizing effect on the pH value in the soil and thus improve the growth conditions for most crops. Both conventionally and in organic cultivation, this is done by adding lime, which, however, must not be dispensed with when using biochar if the soil is not saturated with base (13).
Yield increases are possible through the use of biochar, especially on sandy soils, so that even smaller farms can work economically again and free themselves from the dependence on industrial companies that supply them with expensive and energy-intensive artificial fertilizers, herbicides, insecticides, etc.
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8) Lower Saxony Chamber of Agriculture: Greenhouse gas report on agriculture in Lower Saxony - 2021 edition and IPCC special report on climate change and land systems, 2019
9) https://www.umweltbundesamt.de/daten/land-forstwirtschaft/beitrag-der-landwirtschaft-zu-den-treibhausgas#klimagase-aus-landwirtschaftlich-utilized-ground
10) Federal Agency for Nature Conservation, soil report Diverse soil life - basis for nature conservation and sustainable agriculture, page 16ff; Methane and nitrous oxide were extrapolated to CO2eq
11) https://www.scinexx.de/news/geowissen/ipcc-bericht-klimaschutz-und-land use/
12) See: "Biokohle", eds.: P. Qucker, K Weger, Springer Verlag 2016; Chapter 4.4.3 pH value
13) The clay minerals in the clay-humus complexes in the soil are negatively charged and bind to the positively charged bases calcium, magnesium, potassium, sodium and ammonium. These important nutrients become available to plants because they exchange with other positively charged particles such as hydrogen ions in the soil solution. Calcium is the most important element in terms of quantity (60-70%), followed by magnesium (10-20%). A lack of bases or an unbalanced ratio can lead to soil acidification or the absorption of heavy metals by plants. Related: Neal Kinsey: Hands on
How long does the club exist and where is it based?
The association was founded in 2021 in Hameln, district of Hameln-Pyrmont in the region Weserbergland and Lower Saxony. It was entered in the register of associations under number VR 203512 at the District Court of Hanover on August 4th, 2021.
What is the purpose of the association?
The association pursues exclusively and directly tax-privileged purposes within the meaning of the tax code. The purpose of the association is to promote projects in the fields of education, science, research, environmental protection and climate protection in connection with regenerative agriculture, biochar substrates and Terra Preta cultivation techniques.
The association will be active itself and also act as a fundraising body for other non-profit associations.
In particular, the association will support or operate the projects which serve to reduce greenhouse gas emissions by building up humus using Terra Preta and thus benefit the common good of mankind to a large extent.
The purpose of the statutes is also realized through publications and the implementation of public information events.
(Excerpt from the Articles of Association dated June 23, 2021)
The Effect of Terra Preta
What happens after applying Terra Preta to the soil?
Due to the significantly higher efficiency of fertilization (see above), the yields are already higher in the first few years than in conventional farming. However, the management of the fields is more complex and requires significantly more know-how from the farmers. Microorganisms colonize the biochar and their excrement increases the fertility of the soil. This creates stable biochar humus. Gerald Dunst from the Humus Academy in Kaindorf explains that "from 5% humus in the soil there are without exception stable C/N ratios of 9 to 10 and thus no uncontrollable N losses (14). This means that soil life then organizes itself and only moderate amounts of organic fertilizer are needed to maintain this state. This goal could be achieved much faster with biochar. In heavy rain, the humus-rich soil is able to absorb it more quickly, and in dry periods the increased water storage capacity of biochar and humus is important to stabilize the yield. Both heavy rain events and increasing droughts are predicted in connection with climate change. The humus-rich soil must be permanently protected by greening all year round (catch crops, green manure, undersown crops, mulch, mixed cultures). Tillage should be reduced to an absolute minimum and the application of artificial fertilisers, herbicides and other pesticides should be avoided.
Continuous humus build-up as a global contribution to increasing soil fertility and combating climate change, soil erosion and hunger brought an initiative from France to the climate summit in 2017, which now has many supporters: the 4per1000 initiative was formed, which assumes that with an annual increase of only 0.4% humus, the Paris climate goals for France can be achieved. The Terra Preta e.V. association is a German partner of the 4per1000 initiative.
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14) Agronomy - a slightly different view of soil fertility and fertilization, 2014 and Dietmar Näser: Regenerative agriculture - understanding soil life and plant metabolism, ulmer.de 2020
