Potentially toxic elements in soils and cacao beans in agroforestry systems of Bahia, Brazil. In: Agrotrópica v. 34 n. 2 p. 107-120, 2022.

Abstract

Cacao farming has made many advances in technology and production systems with the goal of increasing final productivity. However, in some cases, the indiscriminate and/or non-technical use of certain agricultural inputs may compromise the quality of the cacao products, like the presence of heavy metals, or potentially toxic elements, such as cadmium (Cd), barium (Ba), copper (Cu) and lead (Pb), compounds of high toxicity and mostly mutagenic and carcinogenic to humans. This work intends to analyze the influence of local lithology and components of agricultural management on the levels of heavy metals in the soil and cacao beans, looking ahead for future evaluations on the consequences of cacao consumption and on the quality demands of the market. The evaluations were made in 15 cacao cropping systems in Southeast Bahia, Brazil. In these cropping systems, cacao was grown under an agroforestry system locally called ‘cabruca’ or under the shade of rubber or erythrina trees. The results suggest that agricultural practices tend to increase the presence of the heavy metals Cu and Ba in the surface soil layers, reflecting the influence of agricultural inputs, and that the higher content of Cd and Pb in subsurface soil layers reflects the influence of lithology processes. Young soils tend to have higher contents of Cu, Cd and Pb than older soil types. Cacao clone PH-16 accumulated higher Ba than beans of Comum ‘forastero’ cacao; soil Ba had direct correlation with Ba in cacao beans and inverse correlation with copper. Soil cadmium tended to have a direct correlation with barium in cacao beans.