Physical–chemical characterization of Amazonian dark earth as influenced by tropical fruticulture in western Brazil’s Legal Amazon

The influence of tropical fruticulture that was established in Amazonian dark earth was investigated by considering changes in soil physical and chemical properties. Soil samples were collected at two layers (0–0.1 and 0.1–0.2 m) under two dissimilar conditions: naturalized archaeological site (Amazonian dark earth) vs. tropical fruticulture.

We evaluated soil texture (clay, sand, and silt contents), bulk density, soil porosity, soil resistance, carbon stock (C stock), soil moisture, geometric mean diameter, weighted average diameter, average diameter < 2 mm, average diameter > 2 mm, soil pH, exchangeable cations (Al³⁺, Ca²⁺, Mg²⁺, K⁺), potential acidity, soil organic carbon (SOC), and available P.

Our results emphasized the soil physico-chemical changes as influenced by tropical fruticulture in the Amazonian dark earth. The PCA and SEM showed that the tropical fruticulture had an overall negative effect on available P, Ca²⁺, GMD, soil aggregation, SOC, C stock, bulk density, and soil resistance.

The results of our study highlighted the importance of considering the Amazonian dark earth as an archaeological site, and when necessary for food production, we must consider soil management practices to promote soil ecosystem avoiding soil quality loss. Thus, long-term experiments in the studied sites considering soil management may exploit different feedback among tropical fruticulture and the Amazonian dark earth.