Making Terra Preta Soil

Terra preta, or "black earth," is a type of soil found throughout the Amazon basin. It is an extremely fertile soil created by inhabitants of the basin many centuries ago as they sought to improve the quality of soil and agricultural production. Scientists are still working to determine a more exact, replicable recipe for terra preta, which has been found to contain human and animal excrement, ash residue, biomass of terrestrial and aquatic plants, cooking refuse, burned clay and other substances.The active and most important ingredient in terra preta, however, is agrichar, also known as biochar. By locating or making biochar, a gardener may improve soil quality, greatly increase carbon content and dispose of certain types of yard, agricultural and house wastes in a productive manner.

Things You'll Need

• Shovel
• Pitchfork or rake
• Brush, scrap wood or logs
• Lighter or matches
• Soil

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Instructions

1. • 1

     Dig a trench or pit in a garden or bed.

   • 2

     Loosen the soil at the bottom of the pit or trench using a shovel, garden rake or pitchfork.

   • 3

     Pile brush, logs or other scrap wood into the trench or pit.

   • 4

     Light the brush pile and monitor the smoke. The smoke will generally begin whitish as water evaporates, then turn yellow with burning sugars and resins. Finally, the smoke will thin and turn gray.

   • 5

     Cover the burning brush — once the smoke has thinned — with about an inch of soil or more depending on how much is needed to significantly reduce the air supply to the burning materials.

   • 6

     Leave the brush to smolder until it has become chunks of charcoal. Put out any remaining fire once the brush has smoldered to this point.

   • 7

     Repeat the trenching throughout the garden. Combine with compost, manure or other nutrient-rich materials tilled into the soil.