As queimadas frequentes e o carbono preto na periferia leste da Amazônia: quantificação analítica e acúmulo no solo

Abstract

Choosing an effective method with features of low cost and easily applicable for most laboratories, particularly in areas with different histories of use, frequency and intensity of the fire, as tropical soils, is of major interest. It is difficult to compare existing estimates of the quantities of carbon black due to this being obtained by different methods. The aim of this study was to assess the usefulness of the method described by Kurth et al. (2006), to estimate the concentration of black carbon in soil profiles from 0 to 1 meter deep in contrasting ecosystems in the eastern Amazon with different historical usage and frequency of fire. The experiment was conducted in areas cleared tracts comprising four (4-7 years), four barns medium (11-15 years), two barns high (20-40 years), five primary forest and pasture, concentrates on 4 'cores' in northern Maranhao and southern Para. The use of fire has a significant effect only in the first layer of soil sampled. The cores show textural variation with increasing depth, which implies variation of the bulk density of the soil. The highest density of soil favor the partial incorporation of carbon black in the fraction of organo-mineral complex with protection held by clay. Clay content and density can contribute to the method Kurth et al (2006) has reduced its efficiency, with greater accuracy for soils with higher concentrations of black carbon (> 2%) and no change in textural sampled profile.