Evaluation of aggregate stability in terrestrial Antropocene markers submitted to different fallow periods

Abstract

Archaeological soils know as Amazonian Dark Earth (ADE) were proposed to be eligible as golden spikes from the beginning of the Anthropocene 2000 years BP (before presente). This hypothesis was highly contested by the international scientific community that pointed out as ADE do not have the necessary geological preservation conditions to serve as golden spikes. One of the main allegations is how ADE is found in natural ecosystems, which are susceptible to natural or anthropic erosion, which would prevent an adequate stratigraphic preservation. Therefore, the objective of this study was to evaluate the stability characteristics of ADE soil aggregates over different fallow periods and to determine if the ADE have a stratigraphic preservation capacity that makes them resistant to rain and mechanical erosion. It was observed that the fallow time did not significantly influence the stability of aggregates of the two evaluated areas and it was observed also that the organic matter of the soil (SOM) did not play a strong role as a cementing agent of the particles due to the oxidic and kaolinite character of these areas. Consequently, a susceptibility to rainfall and anthropic erosion of the ADE was verified, making them unusable as golden spikes from the beginning of the Anthropocene.