An innovative agricultural technology with biochar that increases yields in an ecological manner

Its origin

The black earth discovered in Amazonia, that dates well before the Conquistadors, was nourished with ground charcoal and organic residues. Several thousand years later, this enriched soil is a lot more fertile than the normal one and the charcoal is still present, proving the stability of that type of carbon. See History of biochar

Its recent renaissance

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It is the International Biochar Initiative of Cornell University that started promoting that technology around 10 years ago and has shown that biochar stimulates the soil metabolism and immune defences of the plants that protect them against diseases and insects. On top of that, biochar acts as a water retention agent and is particularly effective in arid soils.
Today biochar is produced by pyrolysis of biomass (heating it to around 500°C in the absence of oxygen), generally crop residues. It is composed of small black fragments, light and porous. The pyrolysis process produces a combustible gas and biochar.

Its agricultural virtues

Ploughing in the soil 300 gr to 1 kg of biochar per m2 increases crop productivity to levels that range from 50 to 200%. Just one application provides and maintains long-lasting soil fertility benefits that enhance carbon sequestration in the soil, thus fighting climate change.
Today, biochar research shows measurable, replicable improvements in soil productivity:

  • Enhances soil biology (40% increase in mycorrhizal fungi)
  • Improves nutrient retention in soils (50% increase in Cation Exchange Capacity)
  • Improves the water retention capacity of soils (up to 18% increase)
  • Increases the pH of acidic soils (1 point pH increase)
  • Increases soil organic matter

Biochar could also be useful for breeding, by its capacity to make animals healthier and to increase the productivity (See Use of biochar for breeding), for decontaminating soils or even for filtering wastewaters (See 55 Usages du Biochar).

Biochar is a powerful mean to mitigate climate change

As plants grow, they draw down atmospheric carbon dioxide (CO2) to produce biomass that contains carbon. Rather than allowing plant matter to decompose and emit CO2, pyrolysis transforms around half of the carbon stored in plant tissue into a stable and inactive form of carbon.

Biochar is also achieving the following:

  • Delays oxidation of soil organic matter
  • Reduces emissions of nitrous oxide (N2O) and methane (CH4)
  • Increases soil organic matter sequestering carbon
  • Increases plant growth
  • Economises water
  • Provides an option to produce renewable electricity by cogeneration

A recent study has estimated that 12% of current annual anthropogenic greenhouse gas emissions could be compensated through biochar.

Production of very high quality biochar by Pro-Natura

Pro-Natura won the Altran Foundation’s first prize for technological innovation with its pioneering pyrolysis unit. The most recent CarboChar machines are producing very high quality biochar in an ecological way from unused and renewable agricultural and forest residues.
The process is:

  • Continuous: 7 days per week, 24 hours a day
  • Autonomous: after ignition, the machine produces its own energy by recycling the pyrolysis gases released by the carbonisation process
  • Polyvalent: all kinds of vegetal biomass can be turned into biochar. If necessary, a dryer and a crusher can be added in order to prepare the biomass for pyrolysis
  • Configurable: the temperature and time that the biomass stays in the machine are optimized to make the most suitable biochar out of every type of organic waste

There are 3 models of CarboChar with daily productions ranging between 1 to 5 tonnes with yields around 40%. See Technical description.

CarboChar-1

The CarboChar-1 is transportable and costs only 70 000 €. It is producing 1 tonne of biochar per day.
The CarboChar-3 allows recovering 45% of the heat produced for co-generation. With an installation consisting of two machines of this type it is possible to produce 1.6 MW of electricity using only the co-generated heat to run a steam turbine and a generator.
In an African context, electricity can be sold at a price of 30 € the MWh and the investment gives a payback of 2 years and an internal rate of return of 29%.

Summary of key scientific publications regarding biochar on main tropical crops

Type of cropAuthorsLocationType of soilsQuantity of biochar (t/ha)Yield increases (%)
RiceAsai et al.Houay-Khot, Nord du Laosupland870%
RiceSteiner et al.Manuas, Brésilxanthic ferralsol / laterite1173%
RiceMasulili et al.Sungai Kakap,
Indonesia
acid sulphate soil1093%
RiceZaitun et al.Empretring, Indonesia-1057%
SugarcaneChen et al.Okinawa, Japanshimajiri maji (clay)7,278%
TomatoEffah et al.Kade, Ghanaforest ochrosol7177%
CottonReddyMidjil Mandal, Andrha Pradesh, Indiaalkaline3,75100%
CabbageCarter et al.Siam Reap, Cambodiasandy acidic100750%
MaizeMajor et al.Llanos Orientales, Colombiasavanna oxisol871%
MaizeMajor et al.Llanos Orientales, Colombiasavanna oxisol20140%
MaizeKimetu et al.Vihiga, western
Kenya
highly degraded ultisol671%
PeanutIslami et al.Malang, Indonesiaclay loam1554%
CowpeaTagoe et al.Gifu, Japansandy loam-146%
CasavaIslami et al.Malang, Indonesiaclay loam1532%
OnionPro-NaturaSenegal-1050%

Summary of key scientific publications regarding biochar on main temperate crops

Type of cropAuthorsLocationType of soilsQuantity of biochar (t/ha)Yield increases (%)
RiceLugato et al.Northern Italyaguic hapludalf4036%
RiceZhang et al.Shenyang, Chinasandy loam3040%
MaizeUzoma et al.Tottori, Japansandy soil15150%
MaizePeng et al.Yingtan, Chinaultisol2,464%
SoyabeanTagoe et al.Gifu, Japan-3,843%
WheatVan ZwietanNSW, Australiaferralsol15170%
WheatVaccari et al.Postoia, Italysilty loam3033%
CanolaPervej-Ahmed et al.Saskatchewan, Canadabrown loam soil120%
BarleyGathorne-Hardy et al.United Kingdomlight soil2043%
Choy sumJia et al.Nanjing, Chinafimi-orthic anthrosol3096%
RadishChan et al.NSW, Australiachromosol1042%
Sweet pepperGraber et al.Israelcommercial soilless mixture879%
Satsuma treeIshii et al.Matsuyama, Japan-83,557%
QuinoaKamman et al.Germanysandy loam brown earth10044%

For more information contact: guy.reinaud@pronatura.org

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