Terra preta (“dark soil” in Portuguese) refers to expanses of very dark, fertile anthropogenic soils found in the Amazon Basin. It owes its name to its very high charcoal content. It is also known as “Amazonian dark earth” or “Indian black earth”. In Portuguese its full name is “Terra preta do índio” or “Terra preta de índio”.

Terra preta is characterized by the presence of low-temperature charcoal in high concentrations; of high quantities of pottery shards; of organic matter such as plant residues, animal faeces, fish and animal bones and other material; and of nutrients such as nitrogen (N), phosphorus (P), calcium (Ca), zinc (Zn), manganese (Mn).It also shows high levels of microorganic activities and other specific characteristics within its particular ecosystem. It is less prone to leaching than surrounding soils. Terra preta zones are generally surrounded by terra comum, or "common soil"; these are infertile soils, mainly Acrisols,but also Ferralsols, and Arenosols

Terra preta soils are of pre-Colombian nature and were created by man between 7000 and 500 BP ("Before Present"). Thousands of years after its creation it is so well known by local farmers and caboclos in Brazil's Amazonian basin, that they seek it out for use and for sale as compost (see Pedology). Its depth can reach 2 metres (6 feet). It is reputedly known by the locals as self-regenerating at the rate of 1 centimetre per year.

Our discovery of Terra Preta, an incredibly fertile soil mixture created and traded by Native  Americans throughout Central and South America, led to intensive study of this amazing  anthropogenic soil. Charles C Mann (2005) is one of the first authors we came across who  discusses this cutting edge indigenous agricultural amendment.   As Mann details, this fertile soil  was found in ample deposits on archaeological sites along river bluffs in the Amazon basin.  It is  called “Terra Preta de Indios”, by Amazonian people  and locals claimed the native indigenous  cultures made it. Archaeologists quickly began to suspect its anthropogenic origins when they
realized that this soil was only found at ancient habitation sites, and invariably contained an  unusually high proportion of pot shards. It was, in essence, a perfect ‘potting soil’ in an area with  otherwise thin, clay based soils with poor aeration. Source One of the amazing things about this soil is the unique composition of microbial life present within  it. Due to microbes present in the soil, concurrent with its high charcoal content, it literally grows!  This may be hard to believe but it has been studied by scientists and shown to actually result in a  net increase in organic matter as Mann documents. The other extremely exciting property of Terra  Preta, is that it contains a high proportion of carbon from charcoal. This carbon acts like a time capsule to literally “lock in” the nutrients around it. Only plant roots contain the ‘combination to  unlock’ these capsules. Rain, wind and sun are unable to leach these precious nutrients away. As it  accumulates nutrients, this contributes to the miraculous ‘growth’ of the soil itself. The addition of  charcoal and the pot shards give the soil loft and structure which better aids agriculture, especially  in a rain forest where drainage and moisture retention must be carefully balanced.
Intensive study into the subject led us to the natural conclusion that this ancient soil creation  technique would have incredible value if understood and utilized by milpa farmers here in Belize,  and throughout the developing world.  In tests done in Brazil, it was found to increase yield by over 800% when added to the soil. This is phenomenal and deserves further study. It is also
interesting to note that so far researchers have been unable to determine how this incredible  microbial balance is achieved. Some speculate that it is created as a starter culture from certain  soils and then added into subsequent batches.
Through studying Terra Preta we have become inspired to create our own modern version, here  at the STAND Center, utilizing natural industrial wastes.  By transporting truckloads of charcoal  from just one, of many, local limestone burning quarries and mixing this in layers with chicken manure, leaf debris, sawdust, or other organic waste, a ‘starter culture’ of microbe rich soil, and river sand, we have been creating our own ‘Terra Preta.’ Our first Terra Preta outreach program is called La Semilla Auténtica’, or The Authentic Seed, and  is a part of a three part program designed to encourage sustainable development in local communities.