Geospatial distribution of cadmium in soil profiles of cacao (Theobroma cacao L.) plantations in the Peruvian Amazon basin

Abstract

Introduction: Cacao plants can translocate heavy metals from the soil to vegetative tissues, potentially leading to concentrations that exceed maximum permissible limits. This study aimed to analyze the geospatial distribution of cadmium (Cd) in soil profiles of cacao (Theobroma cacao L.) plantations in the Amazon basin of Peru. Methods: The research was conducted in the localities of Jeberillos, Arahuante, and Luz del Oriente, within the department of Loreto. In each locality, 10 plots of 100 m² were selected, totaling 30 plots. Cd concentrations and physicochemical soil parameters were evaluated. Results: In cacao soils from Luz del Oriente at 0–30 cm depth, Cd concentrations averaged 1.11 ± 0.26 mg.kg⁻¹, representing the highest values; whereas the lowest average was recorded in Arahuante at the same depth, with 0.61 ± 0.15 mg.kg⁻¹. Cd levels in Luz del Oriente cacao soils (0–30 cm) were above the average among all localities, while Jeberillos and Arahuante soils showed comparatively lower Cd levels. Discussion: Overall, Cd in cacao soils was found to be strongly associated with edaphic factors such as pH, texture, effective cation exchange capacity (CEC), and cation composition. The maps represented the spatial distribution of the metal and guided the identification of potential accumulation zones. These findings provide essential insights for guiding agricultural management decision-making, environmental monitoring, and metal contamination risk assessment in cacao-growing areas and other agrarian systems in the Peruvian Amazon basin.