Terra Preta Making Black Soil In A Raised Bed
I now make my raised beds by using terra preta techniques. The name of the “black soil” of the Amazon Basin in South America is “terra preta.”
Since my home in Kenya is along the beach of the Indian Ocean, my soil is very sandy and nutrient deficient. I had to research how to build my soil so it could support growing edible foods.
My research led me to information about nutrient rich black soil, and specifically the terra preta black soil in the Amazon. Black soil also exists in other places in other places in the world, like in Ghana Africa. People used some similar techniques to make both of these soils.
In Ghana, people built their black soils by dumping the residue of burnt wood, charcoal, food scraps and cooking oil from cooking pits into the soil.
This produced soils that have a very high carbon content that gives the soil its black color. The higher levels of carbon is important because it attracts, binds with, and retains nutrients.
The combination of the carbon and organic materials from the cooking pits also support microorganism reproduction and healthy plant growth.
Terra Preta – Black Soil
Terra preta black soils of the Amazon also appear to be human made. The techniques used to make them developed self sustaining soils. This black soil has been able to produce and support the dense plant life in the Amazon, and its animal inhabitants.
Scientists are still researching how these soils were made. They discovered pits up to 6 feet deep layered with biochar, broken pottery, bone, compost, and manure.
Biochar is partially burnt organic material, like wood, and is similar to charcoal. It is high in carbon and is the main component in building the black soil.
Biochar is very important because it attracts carbon and other minerals from the air and soil, binding and retaining them.
This combination sustains a nurturing environment for microorganisms, supporting plant life and growth.
These soils are regenerative and rebuild themselves by continuously attracting carbon and other minerals.
Terra Preta Black Soil In A Raised Bed
I now build my soil using the terra preta concepts and techniques. But I also have another problem I have to address concerning my raised beds.
There are many coconut trees were I live and their roots are invasive. The coconut roots travel far and deep to search for water, and unfortunately they travel into the soil on my land and into my raised beds.
They compete for the nutrients in the soil my plants need, and the coconut tree roots also choke off my plant roots.
I addressed my concern by putting a 5-6 inch layer of cocoto at the bottom of my raised bed. Cocoto are small rocks broken from bigger rocks.
I also added a layer of sacks over the cocoto, to stop the coconut roots from entering through the bottom of my raised beds.
Terra Preta Layers
To simulate the biochar found in the Amazon terra preta, I added a layer of charcoal on top of the sacks. This is my “carbon layer” at the bottom on my raised bed.
The locals here were I live make charcoal from wood branches that they use for cooking, so I have a steady supply of charcoal.
I then added organic material, consisting of layer of old branches and leaves and top of the carbon layer. Though this layer of organic material also adds carbon, I added this layer to feed the microorganisms.
The microorganisms break down the organic material into compounds and minerals that feed the plants. I mixed in garden soil into this layer. I then added a layer of garden soil and soaked all of the layers with water in my terra preta raised bed.
You can also add a layer of green leaves or kitchen scraps like mango, orange, banana skins, etc. This primarily releases nitrogen adding a nitrogen layer, as the microorganisms decompose them, but also releases other minerals.
The next layer was another layer brown/dried organic material.
I then filled the rest of the raised bed with a mixture and garden soil, and chicken manure and wood chips. People use wood chips for beds for the chickens. The chickens drop their waste and urine on the wood, making it an excellent nitrogen fertilizer. As the wood decomposes it releases its minerals, including calcium.
Now to start planting foods on the Dr. Sebi nutritional guide: