Week of March 4, 2006; Vol. 169, No. 9 , p. 133 Smoldered-Earth Policy: Created by ancient Amazonian natives, fertile, dark soils retain abundant carbon Ben Harder Shortly after the U.S. Civil War, a research expedition encountered a group of Confederate expatriates living in Brazil. The refugees had quickly taken to growing sugarcane on plots of earth that were darker and more fertile than the surrounding soil, Cornell University's Charles Hartt noted in the 1870s. The same dark earth, terra preta in Portuguese, is now attracting renewed scientific attention for its high productivity, mysterious past, and capacity to store carbon....