Journal of Biology and Nature

The search for mineral fertilizers capable of sustainably supporting cocoa production led to an experiment aimed at determining the fertility level of soils under cocoa cultivation in the presence of NPK fertilizers enriched with basic cations. The study aims to conduct to determine the level of soil fertility under cocoa cultivation through the application of NPK fertilisers enriched with basic cations. This work was carried out over two years in three cocoa plantations in the Nawa region, in southwestern Ivory Coast. Data found to be abnormal were transformed using the square root function (√x+0.5) before being subjected to analysis of variance using the GLM procedure in SAS 9.4 software. The mean values were separated using the Student-Newman-Keuls (SNK) method at a 5% threshold. In each cocoa farm, the experimental setup consisted of three complete Fisher blocks with four treatments: T0 was the control without fertilizer, and T1, T2, and T3 were NPK 0-23-19+10 CaO+5 MgO, NPK 0-15-15+17 CaO+5 MgO+ 1 B₂O₃ + 0,5 Zn et NPK 4-10-10+19 CaO+4MgO + 0,8 B₂O₃ + 0,3 Zn, respectively. The results of the chemical parameters determined on 36 composites samples at a rate of 3 per treatment per plot revealed that fertilized soils are less acidic (6.8 ≤ pH ≤ 7.2) compared to T0 (6.1 ≤ pH ≤ 6.5) and more saturated with basic cations (22.6 to 72.4%) with soil organic matter levels peaking at 49.8% in fertilized treatments and 27% in T0. The availability of nutrients (N, P₂O₅, K⁺, Mg²⁺ et Ca²⁺) and micronutrients (B and Zn) in fertilized soils was found to be more significant than in the control. For the ionic balances (S+6.15)/N, K⁺- Ca²⁺- Mg²⁺ (% of S), only that of Ca²⁺ is achieved for all treatments. However, for the others, the emerging trend shows that the ratios calculated for fertilized soils are closer to nutritional balance. In conclusion, it appears that the fertility of soils under cocoa trees can be improved with the addition of mineral fertilisers enriched with basic cations. However, a long-term study would be needed to validate these results. The results reveal that these fertilizers act as mineral amendments by raising the pH of acidic soils towards neutrality. The application of these fertilizers produces sufficient soil organic matter and nutrients, making these soils suitable for cocoa cultivation. Despite these mineral inputs, some ionic imbalances appear in the soil under cocoa trees.