Abstract

Background: Cocoa production in Côte d’Ivoire appears to have reached its limits, with declining yields linked to deforestation, the aging of cocoa plantations, various diseases and pests, and the rapid decline in soil fertility. These soils are generally low in plant-available phosphorus and often have a high phosphorus-fixing capacity due to their high acidity. To address this situation, a three-year study examining the use of reactive natural phosphate (RNP), either alone or in combination with a mineral fertilizer containing phosphorus and potassium (PK), was conducted in Abengourou, in eastern Côte d’Ivoire. Objective: The study aims to ensure the sustainability of cocoa production. More specifically, it seeks to evaluate, on the one hand, the effects of fertilizers on soil nutrients under cocoa trees and, on the other hand, the effects of these fertilizers on cocoa tree yield parameters. Method: The study was conducted using a completely randomized Fisher-type experimental design with 4 replicates for 6 treatments. The collected data were analyzed using analysis of variance (ANOVA) with SAS 9.4 software. Results and conclusion: The results showed that, in terms of soil fertility, the treatments that received natural phosphate generally achieved a good level of available phosphorus (≥ 100 ppm) and a good soil pH (5.55–6.41). All treatments had a cation exchange capacity (CEC) below 12 cmol (+) kg⁻¹ (minimum threshold) and low nutrient content. As for yield parameters, treatments T3 (394 g of PNR + 300 g of PK 23-19 per plant per year) and T4 (296 g of PNR + 300 g of PK 23-19 per plant per year) had the highest rates of wilted pods, with 54.67 and 54.91, respectively. For total pod count, treatment T4 (37.48 pods) had the highest value. Regarding the average weight of fresh beans, treatments T3 and T5 (300 g of PK 23-19 per plant per year) yielded the best results: 170 g and 176.70 g, respectively. In terms of potential yield, treatments T2 (2,510.21 kg/ha) and T3 (2,652.59 kg/ha) also yielded the best results. These treatments can be recommended to cocoa farmers in the region to raise the pH of acidic soils, thereby improving cocoa tree nutrition and ensuring sustainable production.

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