Terra Preta

Origins in South America

Terra preta ( Portuguese for ” black earth ” ) can be found in the Amazon basin and was made by human hands .

Terra Preta is made by adding ash, biomass, kitchen waste, pyrogenic carbon and bones to the soil over many years. The most important part of the genesis of Terra preta is biochar, which adds stability due to its slow degradation; but for its creation and maintenance, nutrients and microorganisms are also required.

The indigenous populations have learned to understand and holistically use these biogeochemical cycles.

They collected organic materials in large clay pots with lids and a bottom outlet:

  • Fresh vegetable residues of all kinds
  • Animal and human faeces
  • Minerals
  • Clay minerals
  • Charcoal
  • Lactic acid bacteria

They fermented the mixture by putting a lid on the pottery and after a few weeks thez had Bokashi. Then, the pots were smashed, to allow the Bokashi to oxidize. After a few weeks crops were grown on it.

The solution for a stable supply of carbon

Plants gain carbon (C) through photosynthesis. The main problem of this process is the waste of carbon through rotting and composting. High quality carbon ( as Bokashi ) is quickly sapped off the ground in the form of nutrient humus. Biochar, vivified to Terra Preta ( Terra Preta effect ), is the solution for stable carbon supply.

We have immense amounts of carbon available through the photosynthesis in plants. A good soil structure combines nutrient humus ( Bokashi ) and stable humus ( biochar ), because biochar must be vitalized to the achieve desired effect. For the vitalization of nutrient humus to work, Bokashi and microorganisms that colonize the surface are required.

Properties of Terra-Preta

  • Up to 60% of organic matter ( C )
  • Extremely high humus values
  • Nutrient binding capacity ( N.p , K , Mg , and high volumes of all trace elements )
  • Buffering capacity is extremely high
  • Age 500 years to a few thousand years
  • Even today, three very profitable crops per year can be obtained from these soils. Without fertilization and without plant protection !

terra_preta_cloeUpAnd this in an area where between 2000 and 4000 mm ( liters ) per m² per year of rainfall. The soils do not wash out because they have large amounts of ultra- high-strength permanent humus. Biochar acts as a sponge for nutrients and a texturing agent. But the critical element is its biological involvement in the formation of the coal- humus-microbial compound. The highly porous structure of biochar, as seen here under the microscope, enables high nutrient and water storage. Specific surface area of biochar: 200 to 300 square meters per gram

What do we want to achieve with the production of biochar ? 

Basically, we want to close natural cycles and use the soil’s own organic matter. Slurry, manure and compost should be optimally used to produce nutrients and stable humus forms.

The process should lead to a reduction in the use of mineral fertilizers and pesticides, to regenerate cultivated soils ( degradation of pollutants, much organic matter in high quality lead to humic acids ) . Ultimately, this leads to the development of a stable Clay-Humus environment.

Advantages of the Terra-Preta principle

  • Fertilizer and humus
  • Fertility and healthy growth
  • Water-retentive and humidity regulating
  • Reduction of pesticides, herbicides and fungicides
  • Binding of CO2 in the soil = climate change
  • No breakdown of organic matter in soil