Background: The cocoa crisis in the 1970s decade in Côte d’Ivoire was manifested by the proliferation of crops pests, reduced production and decreased rainfall. To cope with all these constraints, the producers adopted various strategies, including the use of agricultural inputs to improve the production. Thus, this study aimed to characterize the effects of these inputs on water-soil couple. Methods: First, 12 soil and surface water samples were taken for analysis. Second, determination of trace metal content was done using an atomic absorption spectrophotometer (AAS). Also chemical elements were analyzed using a HACH DR 6000 spectrophotometer. Results: Soil concentrations of exchangeable base Ca2+, K+ and Mg2+ are low with average values of 5.71 cmol/kg, 0.35 and 1.66 cmol/kg, respectively. The soils of cocoa orchards are quite rich in assimilable phosphorus (P). The average phosphorus content is 24.31 cmol/kg with a minimum of 3.92 cmol/kg and a maximum of 78.4 cmol/kg. The study of surface water quality showed that the average values of biochemical oxygen demand for 5 days (BOD5) (18.64 mg/L) and chemical oxygen demand (COD) (15.49 mg/L) are lower than the respective standards of 25 and 125 mg/L of the world health organization (WHO) standard. These surface waters have average concentrations of 0.015 mg/L for cadmium (Cd), 0.042 mg/L for zinc (Zn) and 0.062 mg/L for manganese (Mn), below the respective standards of 0.003, 3 and 0.4 mg/L. Conclusion: This study shows that surface waters are not yet very polluted by these inputs.

The impact of earthworms and plant growth-promoting rhizobacteria (PGPR) on the remediation in polluted dumpsite soil was performed in a greenhouse pot culture with Acacia mangium inoculated or not (control: T0) with Pontoscolex corethrurus (T1) and with Bradyrhizobium (T2); and inoculated with Pontoscolex corethrurus and Bradyrhizobium (T3). Our results showed the presence of Bradyrhizobium and/or earthworms significantly increase (P < 0.05) in the height (2-fold), total dry biomass weight (7- to 15-fold) and metal uptake of the plant (2 to 10-fold), as compared with the non-inoculated plant. The presence of both inoculants (Bradyrhizobium and earthworm) enhanced soil Pb/Ni/Cr mobility and bioavailability in metal-contaminated soil, and increased 15-fold the total plant biomass and 10-fold metal accumulation in plant biomass, as compared with plant inoculated with earthworms or Bradyrhizobium. In addition, the presence of earthworms and/or Bradyrhizobium promoted the phytoimmobilization process of Ni, Cr and Pb preferentially in Acacia mangium roots than in shoot tissue. Our experiments highlight the importance of soil organisms on the phytoremediation efficiency. It appears that earthworms and/or Bradyrhizobium have the potential to enhance the phytoextraction efficiency of plants in metal-contaminated soil.