Sir

Your recent News Feature “Black is the new green” (Nature 442, 624–626; 2006 10.1038/442624a) accurately summarized the origin, discussions and goals of the Terra Preta Nova group at the recent World Congress of Soil Science in Philadelphia.

However, one might be left with the impression that the biochar initiative is solely directed towards agribusiness applications. From the start, this has certainly not been the case. Indeed, innovative biochar field trials involving a variety of crops are currently being conducted in Amazonia by researchers in Embrapa, the Brazilian agricultural research corporation, and INPA, Brazil's national institute of Amazonian research. These trials are specifically designed for implementation by smallholders, who comprise most of the world's farmers. At the same time, the Brazilian researchers are seeking answers to the questions raised in Philadelphia about the native terra preta of Amazonia, even as US and European researchers are taking the concept in new directions.