But the socalled Terra preta, black soil. Something you may even tryout your self if you have some land with the suited kind of soil.. Its like a Indiana Jones story..
"Terra preta (which means "dark soil" in Portuguese) refers to expanses of very dark soils found in the Amazon Basin. It is also known as "Amazonian dark earth" or "Indian black earth". In Portuguese its full name is Terra preta do indio or Terra preta de indio.
For a long time, the origins of the Amazonian dark earths were not immediately clear and several theories were considered. One idea was that they resulted from ashfall from volcanoes in the Andes, since they occur more frequently on the brows of higher terraces. Another theory considered formation as a result of sedimentation in Tertiary lakes or in recent ponds.
However, because of their elevated charcoal content and the common presence of pottery remains, it is now widely accepted that these soils are a product of indigenous soil management involving a labor intensive technique termed slash-and-char. The technique is differentiated from slash and burn by a lower temperature burn and in being a tool for soil improvement. "
http://en.wikipedia.org/wiki/Terra_preta
charcoal... thats it.. you burn your own, or by it and mix it with the soil... then after a seson, or maybe longer you will be able to see if there is something into this.. you could make a blog so us who dont have any soil to play with could follow your experiment..
whatya think?
