The First National Survey of Cadmium in Cacao Farm Soil in Colombia

Daniel Bravo,Carlos Alberto Martínez,Gustavo Alfonso Araujo-Carrillo,Clara Leon-Moreno,Ruth Quiroga-Mateus,Viviana Marcela Varón-Ramírez,Annie Zamora,Edwin Antonio Gutiérrez Rodríguez,Ruy Vargas

doi:10.3390/agronomy11040761

Abstract

This study represents the first nationwide survey regarding the distribution of Cd content in cacao-growing soils in Colombia. The soil Cd distribution was analyzed using a cold/hotspots model. Moreover, both descriptive and predictive analytical tools were used to assess the key factors regulating the Cd concentration, considering Cd content and eight soil variables in the cacao systems. A critical discussion was performed in four main cacao-growing districts. Our results suggest that the performance of a model using all the variables will always be superior to the one using Zn alone. The analyzed variables featured an appropriate predictive performance, nonetheless, that performance has to be improved to develop a prediction method that might be used nationwide. Results from the fitted graphical models showed that the largest associations (as measured by the partial correlation coefficients) were those between Cd and Zn. Ca had the second-largest partial correlation with Cd and its predictive performance ranked second. Interestingly, it was found that there was a high variability in the factors correlated with Cd in cacao growing soils at a national level. Therefore, this study constitutes a baseline for the forthcoming studies in the country and should be reinforced with an analysis of cadmium content in cacao beans.

Highlights

Cadmium (Cd) is a nonessential heavy metal, which can be found in soil under many uses, including agriculture, pasture, forest and wasteland [1,2]
On the one hand, regarding the soils where cacao is cultivated, the variability of Cd concentration in cacao beans from different sites has been attributed to the “total” soil Cd content and its relationship with critical soil factors influencing Cd phytoavailability, such as Cd soil mobility, pH, texture and soil organic matter (SOM) [8]
The present study aims to analyze the spatial distribution of Cd and the relationships between this heavy metal and the soil parameters in cacao-producing districts in Colombia, focusing on regions with the highest production

Summary

Introduction

Cadmium (Cd) is a nonessential heavy metal, which can be found in soil under many uses, including agriculture, pasture, forest and wasteland [1,2]. The presence of this metal in cacao-growing soils has become one of the biggest challenges to produce safe cocoa in South and Central American cocoa-producing countries [3,4,5]. On the one hand, regarding the soils where cacao is cultivated, the variability of Cd concentration in cacao beans from different sites has been attributed to the “total” soil Cd content and its relationship with critical soil factors influencing Cd phytoavailability, such as Cd soil mobility, pH, texture and soil organic matter (SOM) [8]

Methods

Results

Discussion

Conclusion