Study of Carbon Nanostructures for Soil Fertility Improvement

Keeping organic matter in the soil is one of the most promising carbon capture and storage methods. Soil organic matter has the longest soil persistence and cause soil amelioration. The “Terra Preta de Indio” (Amazonian Dark Earth) is an anthropogenic Amazonian soil that provides a potential model for such organic matter soil storage, generating a sustainable land-use system that is highly efficient even in the hot and humid tropical regions. The large amount of carbon-based materials in these soils is responsible for their unusually high fertility over long periods of usage. In this chapter, by applying materials science tools, including scanning and transmission electron microscopy, energy dispersive X-ray, electron energy loss spectroscopy and Raman spectroscopy, we show that these millenary carbon materials exhibit a complex morphology, with particles ranging in size from micrometers to nanometers, from the core to the surface of the carbon grains, and are rich on specific elements that are important for fertility and carbon stability. Specifically, calcium and oxygen are abundant in the whole carbon structure, and the role of these elements on carbon stability is studied theoretically. From one side, our results might elucidate how nature solved the problem of keeping high levels of ion exchange capacity in these soils. From the other side, morphology and dimensionality are the key issues in nanotechnology, and the structural aspects revealed here may help generating the “Terra Preta Nova” (New Black Earth), effectively improving world agriculture and ecosystem sustainability.