02275naa a2200241 a 450000100080000000500110000800800410001902400540006010000190011424501640013326000090029752013540030665000130166065300080167365300210168165300190170265300280172165300260174970000210177570000220179670000200181877301950183813351082022-03-29       2009    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1007/978-1-4020-9031-8_212DOI1 aNOVOTNY, E. H.  aSolid-state 13C nuclear magnetic resonance characterisation of humic acids extracted from amazonian dark earths (terra preta de índio).h[electronic resource]  c2009  aSoils are one of the most important natural resources, and are essential for the development and continuation of any society that practices agriculture. Ancient civilizations in the Old World generally began in valley regions and floodplains along big rivers. As examples, one can cite Egypt in the Nile River valley, the Mesopotamia between the Tigris and Euphrates rivers, the Indian Subcontinent by the margins of the Indus and Ganges rivers, and China in the valleys of the Yellow and Blue rivers. In different areas of the world, many detailed comparisons have been accomplished between natural and human influenced soils, and the results of the latter have been documented (Cunha 2005) In the last decades, agricultural activities have been modifying the original vegetation cover of a great part of the Brazilian territory. Ecosystems, such as the Amazon forest, are losing their original characteristics, being replaced by agricultural and extractive activities. The expansion of the agricultural borders has been causing great changes in forest areas in Brazil, with the introduction of rice, soybeans, and pastures, mainly in the southern part of the Amazon area. This has lead to degradation and a loss of biodiversity, a reduction in organic matter, and also the degradation of the pedologic covering, through the exhaustion and erosion.  aAmazonia  a13C  aÁcidos húmicos  aEspectroscopia  aRessonância magnética  aTerra Preta de Índio1 aBONAGAMBA, T. J.1 aAZEVEDO, E. R. de1 aHAYES, M. H. B.  tIn: WOODS, W. I.; TEIXEIRA, W. G.; LEHMANN, J.; STEINER, C.; WINKLERPRINS, A.; REBELLATO, L. (ed.). Amazonian dark earths: Wim Sombroek's vision. Berlin: Springer, 2009. cap. 21, p. 373-391.