Terra Preta

Terra Preta

(Portuguese for "black earth") is the name for a fertile humus soil, consisting of a mixture of biochar (at least 10%), animal excrement and either fermented or composted plant residues. The biochar is chemically and physically neutral and remains in the substrate for several hundred years. The oldest Terra Preta found in the Amazon is over 7,000 years old. The high porosity of the coal offers bacteria and microorganisms an ideal habitat and thus ensures an active soil life. In addition, the charcoal has the properties of storing nitrogen, other nutrients and water and keeping them available to the plants for a longer period of time. After a maturing time of approx. 3 months under anaerobic conditions with only mild heat development (different with composting), a substrate with many living organisms is created that resembles a loose, crumbly forest soil and has a mushroom, nutty smell. The loss of mass is only approx. 2% compared to approx. 50% with traditional compost.

All infectious bacteria are then metabolized by the acidic fermentation process. The substrate applied to the field also invigorates the field soil and becomes a very fertile humus soil. The use of inorganic, chemical fertilizer is then no longer necessary and is replaced by the work of microorganisms, which are now fed by mulch or green mulch. From a humus content of approx. 5.5%, the soil organisms organize themselves in the substrate, so that the humus content continues to grow while absorbing greenhouse gases from the atmosphere. Plant residues remaining on the field after harvest are then completely metabolized by the organisms of the humus soil (mulching) and thus continue to increase the humus proportion in the arable farm land.

In many scientific studies some significant increases in yield of the harvest were noted as well as in practical application in the fields. These increases in yield turn out to be proportionally higher, the worse the starting soil was before the Terra Preta use.

A corresponding certificate guarantees the perfect quality of the Terra Preta substrate.

In addition to agriculture, Terra Preta is also very well suited for use in private gardens and in gardening and landscaping companies and has been used successfully there for many years.

Experts from the “Regeneration International” initiative and the French “4 per 1000” initiative assume that the climate targets agreed in Paris will only be achieved through the widespread use of humus formation as a substitute for chemical soil fertilization (which makes the fields themselves greenhouse gas emitters).

This magnificent garden, which was created with workshop participants at the Holzen / Ith education center, grows to approx. 10 to 15 cm Terra Preta, made from lawn clippings, horse manure, charcoal and effective microorganisms. Since seeds and some young plants need a slightly acidic pH value, Terra Preta can also be made with normal compost, as was done here.

Authors:  Rainer Sagawe & Dr. Stephan Martini, Hameln, Germany, December 2020