48 research outputs found
Physical, chemical, and mineralogical attributes of a representative group of soils from the eastern Amazon region in Brazil
Amazonian soils are heterogeneous. However, few studies have been
carried out in the Amazon, mainly because of its considerable size, which
complicates the collection of data and the ability to plan for the
sustainable use of natural resources. In this study, the physical, chemical,
and mineralogical attributes of soils in the state of Pará, Brazil, were
characterized by examining the particle size, fertility, silicon extracted by
sodium hydroxide, iron, and aluminum, and manganese extracted by sulfuric acid,
sodium citrate-bicarbonate-dithionite, and ammonium oxalate + oxalic
acid. A descriptive analysis, multivariate principal component analysis, and
cluster analysis were performed. The soils had low concentrations of
bioavailable P, Ca2+, Mg2+, and K and had high
concentrations of Al3+, Si, and Al oxide in the Cambisols.
Concentrations of Fe and Mn oxides were higher in both the Cambisols and
Nitosols, which are rich in oxidic minerals. The multivariate analysis
indicated an association between the organic carbon content and pH, P, Ca,
Mg, and K concentrations. An additional association was observed between
clay, potential acidity, and the Fe and Al oxide concentrations.</p
CHARACTERIZATION OF YELLOW LATOSOLS (OXISOLS) OF SERRA DO QUILOMBO, IN PIAUÍ STATE SAVANNA WOODLANDS - BRAZIL
Intentional creation of carbon-rich dark earth soils in the Amazon.
Fertile soil known as Amazonian dark earth is central to the debate over the size and ecological impact of ancient human populations in the Amazon. Dark earth is typically associated with human occupation, but it is uncertain whether it was created intentionally. Dark earth may also be a substantial carbon sink, but its spatial extent and carbon inventory are unknown. We demonstrate spatial and compositional similarities between ancient and modern dark earth and document modern Indigenous practices that enrich soil, which we use to propose a model for the formation of ancient dark earth. This comparison suggests that ancient Amazonians managed soil to improve fertility and increase crop productivity. These practices also sequestered and stored carbon in the soil for centuries, and we show that some ancient sites contain as much carbon as the above-ground rainforest biomass. Our results demonstrate the intentional creation of dark earth and highlight the value of Indigenous knowledge for sustainable rainforest management