Ancient Soil Secret

Conventional wisdom had long held that the soils of the Amazon basin were poor in quality: loose in texture, burdened by too much aluminum, and depleted by torrential rainfall. But in 2001 scientists from several countries became aware of a mysterious substance the locals called Terra Preta, or Dark Earth. Extensive tracts of land in the heart of the Amazon were blessed with rich dark soil where logic suggested none should exist. This soil was not only remarkably fertile, but had endured despite centuries of human inactivity, the result of the local culture’s disruption by early European explorers. For the past eight years scientists have struggled to understand the Black Magic behind these apparent contradictions.

A consensus has emerged about the magic of Terra Preta focused on Biochar, an organic charcoal created with a low oxygen fire which merely chars vegetable matter, rather than burn it completely. While no one has been able to duplicate Terra Preta exactly, it now seems clear that adding biochar to the soil was the key ingredient in its formation. The good news is that we don’t need the precise formula for Terra Preta to get tremendous benefits from biochar. Properly applied, biochar is capable of doubling, even tripling, the fertility of most soils. It also reduces the need for chemical fertilizers by 75%, and reduces greenhouse gases emissions of the land it’s used on. Even better, biochar is the gift that keeps on giving. Unlike fertilizer, it persists in the soil for hundreds, even thousands of years. In the process it removes carbon from the atmosphere. As a result climate change activists are starting to embrace biochar as a potent way to fight global warming.

You too can use biochar to improve your garden this spring! The Gardening With Biochar FAQ web site is filled with helpful information, and is a great place to start. For simple ways to make biochar in the back yard with a steel barrel, check out the Official Biochar Tutorial Video or this Making Charcoal page. An overview of basic techniques to create biochar can also be found at Simple Technologies For Charcoal Making, an on-line document produced by the Food and Agricultural Organization of the United Nations.

(Originally posted by R. Guenette on 02.05.09)

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