georgi345
Active Member
-from ==> http://en.wikipedia.org/wiki/Terra_pretaTerra preta (literally “black earth” in Portuguese) refers to expanses of very dark, fertile anthropogenic soils found in the Amazon Basin. Terra preta owes its name to its very high charcoal content, and was indeed made by adding a mixture of charcoal, bone, and manure to the otherwise relatively infertile Amazonian soil over many years.[1] 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 mulata is lighter or brownish in color.[2]
Terra preta is characterized by the presence of low-temperature charcoal in high concentrations; of high quantities of pottery sherds; of organic matter such as plant residues, animal feces, fish and animal bones and other material; and of nutrients such as nitrogen (N), phosphorus (P), calcium (Ca), zinc (Zn), manganese (Mn).[3] It also shows high levels of microorganic activities and other specific characteristics within its particular ecosystem. It is less prone to nutrient leaching, which is a major problem in most rainforest soils. Terra preta zones are generally surrounded by terra comum, or "common soil"; these are infertile soils, mainly acrisols,[3] but also ferralsols and arenosols.[4]
Terra preta soils are of pre-Columbian nature and were created by humans between 450 BC and AD 950.[5][6] The soil's depth can reach 2 metres (6 feet). Thousands of years after its creation it has been reported to regenerate itself at the rate of 1 centimetre per year[7] by the local farmers and caboclos in Brazil's Amazonian basin, and they seek it out for use and for sale as valuable compost.
i'm very intrigued by this and there seems to be a good amount of growing literature/awareness out there on the subject, but i have as yet to see/find anything directly related to mj growth and the use of charcoal as a soil amendment...
'anybody have any experience with this? benefits? detriments? advice?
i'm going to be giving it a go in my next grow, substituting the charcoal in for a portion of my regular amount of perlite, giving a final perlite-charcoal ratio of 3:1 (this gives me a total of c16% charcoal in my soil mix)...
this seems to be in line (on the low side) with the normative range apparently found in terra preta:
2,000,000pounds / 43,560square feet = 45.9137pounds per square foot to a 6" depth
46 lbs. x 10% = 4.6 lbs.
46 lbs. x 20% = 9.2 lbs.
46 lbs. x 30% = 13.8 lbs.
A Terra Preta soil that had charcoal / bio-char to a depth of 2' at a 10% concentration would have 18.4 pounds of biologically active carbon under each square foot of surface area. That would be 36.8 lbs. and 55.2 lbs. at 20% and 30% concentrations respectively
(see here for source and further non-mj specific discussion ==> http://forums2.gardenweb.com/forums/load/soil/msg070428251066.html )
your thoughts, all?
cheers
-g