Thanks to biochar, a mighty soil rich in nutri­ents and humus has devel­oped in some areas of the Amazon over the cen­turies. This can also be achieved on Euro­pean soils. Bruno Glaser, soil bio­geo­chemist and pro­fes­sor at the Uni­ver­si­ty of Halle, comes to this con­clu­sion in his article on “The Terra Preta Concept”. However, it is not enough to mix pure char­coal from the DIY store into the soil. Nutri­ents must also be intro­duced and the biochar acti­vat­ed. This can best be achieved by com­post­ing with biowaste. Accord­ing to Glaser, for most farmers this means that they have the “ingre­di­ents” for an improved soil at their dis­pos­al without much addi­tion­al effort.

What is terra preta and why is it so interesting?

The Ama­zon­ian Black Earths (terra preta) were one of the inex­plic­a­ble wonders of human history until a few years ago. While most of the primeval forest soils are highly infer­tile, Terra Preta, some of them more than 2000 years old, still has high reserves of nutri­ents and stable, carbon-rich soil sub­stance. Terra preta is of human origin and is a mixture of human and animal excre­ments and veg­etable waste, some of which have been charred and composted.

The role of biochar

Due to the cli­mat­ic con­di­tions there is hardly any humus for­ma­tion in the tropics, whereby soil organ­isms such as ter­mites, ants, earth­worms etc. convert dead leaves and roots step by step into humic sub­stances. Instead, these sub­stances are com­plete­ly degrad­ed. In terra preta, on the other hand, humus build-up takes place due to the sta­bil­is­ing effect of biochar. Biochar acts as a reser­voir for organic carbon (C‑storage is 3 times as high as in neigh­bour­ing rain­for­est soils), nutri­ents and water. Terra preta con­tains 2–3 times more nitro­gen and 4–5 times more phos­pho­rus than neigh­bour­ing rain­for­est soils. Further pos­i­tive effects are reduced washout losses and a loos­en­ing of soils rich in clay.

Poten­tial of biochar for agriculture

Accord­ing to Glaser, the com­par­a­tive­ly simple pro­duc­tion of terra preta allows farmers to upgrade their land, save money on fer­tilis­er and receive credits from emis­sion cer­tifi­cates. The improved soil fer­til­i­ty can in turn lead to higher yields, which will be suf­fi­cient to feed the world’s pop­u­la­tion and satisfy its energy needs (through addi­tion­al heat and energy pro­duc­tion in the pro­duc­tion of biochar). In addi­tion, by reduc­ing the carbon dioxide content of the atmos­phere, they con­tribute to saving the world’s climate. Ulti­mate­ly, this also increas­es the value of rural areas as they make a sub­stan­tial con­tri­bu­tion to decen­tralised energy supply.

Orig­i­nal article: Das Terra Preta Konzept. Chancen für ein nach­haltiges Man­age­ment natür­lich­er Ressourcen (The Terra Preta concept. Oppor­tu­ni­ties for sus­tain­able man­age­ment of natural resources)
Author: Prof. Dr. Bruno Glaser
Pub­lished in: Müll und Abfall 03/2012, Springer Verlag