What is Terra Preta and why is it worth making it?
Terra Preta (Portuguese: black earth) is an achievement of the ancient Indian high cultures in the Amazon Basin. Fields that are regularly treated with plant charcoal have 10 to 20 percent organic carbon (humus), up to five times phosphorus and nitrogen content often over the entire soil profile of one meter and more. All the experts are positively surprised about this fact!
In Switzerland, we deal with soils that have only 0.5 to 1 percent carbon content and this only a few centimeters deep. Good arable land have up to 3 per cent of carbon and good garden soils have rarely more than 5 per cent. Nevertheless, even here the gardening and the yields are already quite enjoyable! Imagine an earth that has 15% stable organic carbon (humus) over a full meter of thickness. The amounts of nutrients and water that can store such a soil, and provide the perfect healthy diet for plants. In addition such a soil contains natural life in it, such as bacteria, fungi and earthworms whose positive effect to the growth of plans is very positive, but difficult to quantify.
In the case of “good professional practice”, it is possible to use conventional methods to build up a maximum of 1 percent organic carbon in 40 to 60 years. The reality, however, is that modern agriculture with its management methods causes rather a humus degradation. With the use of plant-charcoal in agricultural land, the soil power would increase since the CO2 would fixed the in the soil.
The most striking feature of Terra Preta floor is that the “plant charcoal” distributes over the entire floor profile. Since virtually any organic material, not just wood, can be carbonized, it is better to denote it as biocarbon. For example, biochar from straw, bark, harvest residues or modern methods can even be produced from wet kitchen waste. Biocarbon is stable in the soil over a thousand years and is hardly chemically or biologically degraded. Biocarbon is similar to humus in soil. The spongy, porous structure of the biocarbon can store large amounts of water and nutrients available to plant roots on demand. This ensures a perfect and uniform diet of the plants. In the cavities of the biocarbon, complex living communities of microorganisms and larger soil organisms can settle, perfectly protected. They likely will persist even in unfavorable times such as drought and nutrient deficiencies times. The latter are expected to be frequent in the future because of climatic warming.
Microorganisms (EM) and their habitats (bio-charcoal) are very good for the agriculture. It is they who decompose “eat” the organic waste. The cycle of life is closed on a small scale. Healthy soils produce healthy plants and food for animals and humans. We can learn the cycle of life again. Nature knows no waste! The unknown civilizations that left us Terra Preta made us the most precious gift. With this knowledge we could create our own paradise.