Cadmium concentration in cocoa beans produced in agroforestry systems of small producers in Panama

Abstract

Aim of study: To calculate Cd concentration in cocoa plants and evaluate its relationship with available Cd and other soil properties. Area of study: Almirante, Bocas del Toro province, Panama, in 2020-2021. Material and methods: The study was carried out in 21 plots of eight cocoa-producing farms. The total area of each sampled plot was 300 m2. Soil samples were taken at a depth of 30 cm, and samples of the leaves and fruits of cocoa trees were also taken. Descriptive statistics and correlation analyses were carried out for soil variables and Cd in plants. The relationship between bioavailable Cd and soil physicochemical variables and between soil variables and Cd in plants was evaluated. Multiple linear regression was performed using the backward selection method. Main results: The pH was acidic (5.1) and the organic matter content of the soil was greater than 3%, suitable for immobilizing Cd from the soil. Total and bioavailable Cd averaged 0.10 mg kg-1 and 0.02 mg kg-1 respectively. The Cd levels in cocoa leaves exceeded the recommended levels of 0.5 mg kg-1. The Cd concentration in the cocoa bean was low (0.25 mg kg-1). Research highlights: The levels of bioavailable Cd found do not exceed the United States Environment Agency toxic limits in soil. The level of Cd found in the cocoa bean is below the limit of 0.8 mg kg-1 which is taken as a reference for chocolate, with total dry matter content ≥ 50% of the CODEX Alimentarius.

Keywords

• soil organic carbon
• Inceptisol
• soil pH
• aluminum saturation
• toxicity
• soil contaminants