In response to the continuing decline in the fertility of tropical agricultural soils, the use of grain legumes has been developed as an alternative form of organic fertilization, as it integrates the conservation and sustainable management of biodiversity. The present study, conducted in the Karamokola area in central-western Côte d’Ivoire, falls within this framework and aims to compare the effect of two legume crops (soybean: Glycine max and bean: Phaseolus vulgaris) on soil macroinvertebrates. To this end, an experimental design consisting of four randomized blocks comparing four treatments (beans, soybeans, beans and soybeans, and a control) was set up on two fallow plots that were more than five years old. The results showed that the plots with a previous monoculture of beans and a previous mixed crop (beans and soybeans) harbored 15 taxonomic groups, compared to 10 groups for the control. In addition, there was a greater abundance of macroinvertebrates, with 675.75 individuals per m2 (previous bean monoculture) and 653.25 individuals per m2 (previous bean-soybean intercropping). Furthermore, soybean monoculture hosted an intermediate abundance of macroinvertebrates of 156.12 individuals per square meter.In addition, bean monoculture significantly improved (p˂0.05) the organic matter content (OM = 1.82%), carbon (C = 1.06%), and nitrogen (N = 0.09%) content of the soil compared to the other treatments (soybean monoculture and bean-soybean combination), which recorded statistically identical values (OM = 1.00% soybean and 1.17% bean-soybean); C = 0.58% soybean and 0.68% bean-soybean: N = 0.05% soybean and 0.06% bean-soybean). The positive correlations (r ≥ 0.85) between soil organic status and macroinvertebrate density, taxonomic richness, and Shannon diversity index suggest a synergistic relationship between these two compartments (soil organic status and density). The mechanisms governing the increases in abundance and diversity under the bean and bean-soybean treatments are discussed, and we recommend that farmers grow beans or bean-soybeans before planting any other crops in the Karamokola area of Béré in Côte d’Ivoire.

Chromolaena odorata is a fast-spreading invasive plant species that poses a serious threat to agricultural ecosystems, particularly in sub-Saharan Africa. Despite its reputation as a harmful weed, there has recently been an increase in interest in its potential use as an organic soil improver. This study evaluates the impact of C. odorata biomass on soil physicochemical properties, specifically pH and moisture content, as well as on the agronomic performance of maize (Zea mays). The experiment was conducted in Zépréguhé, in the Haut Sassandra region of central-western Côte d’Ivoire, using a randomised complete block design. Four treatments were tested: C. odorata biomass alone; C. odorata combined with a 170 kg/ha mineral fertiliser (NPK 15-15-15); mineral fertiliser alone; and an untreated control. A single maize variety (LG-501) was used to ensure consistency across the treatments. The agronomic parameters measured included plant height, the number of leaves, the stem base diameter and the yields of ears and grain. Soil pH and moisture were also assessed. The results showed that the treatments involving C. odorata significantly enhanced plant growth and increased soil moisture, while slightly neutralising soil acidity. Applying C. odorata alone produced the highest yields (10.74 t/ha for ears and 7.62 t/ha for grain), outperforming the mineral fertiliser treatment and the control. The combination treatment also yielded good results, albeit slightly lower. These results suggest that C. odorata biomass could be used as an effective, inexpensive alternative to or addition to synthetic fertilisers, thereby promoting soil health and sustainable maize production in tropical agroecosystems.

The aim of the study was to assess the impact of cocoa-based agroforestry practices on natural soil productivity. The methodology consisted in identifying three cocoa-based agroforestry systems (simple, mixed or complex) guided by the opening of the canopy of various floristic species associated with cocoa trees, in which three 100 m2 plots were randomly set up to inventory the arboricultural species encountered, determine species density and plantation yields. The results identified 17 tree families divided into 27 plant species, of which 55.55% were found in the simple agroforestry system (SAGS), with a density of 55 trees/hectare, 70.37% in the mixed agroforestry system (SAGM), with a density of 155.33 trees/hectare, and 81.40% in the complex agroforestry system (SAGC), with a density of 224.33 trees/hectare. In terms of particle size, the SAGS and SAGC had a silty texture, whereas the SAGM had a silty-clay texture. Major element, trace element and clay-humus complex contents were satisfactory in all agroforestry systems, but in decreasing order in SAGM, SAGC and SAGS. Cocoa productivity was higher in SAGS (403.42kg/ha), than in SAGM (293.61kg/ha) and SAGC (204.68kg/ha). In conclusion, it should be noted that each forest agrosystem has very distinct characteristics and contributes to soil fertility at depths of 0-20cm. Moreover, SAGS is the agroforestry system with the best production and can be recommended during the establishment of cocoa plantations in Côte d’Ivoire.

Most cocoa growing soils currently have a low level of chemical fertility. This does not make it possible to optimize the development of cocoa trees and ensure sustainable cocoa production. The objective of this study was to improve the fertility of soils under cocoa trees and cocoa production in Côte d’Ivoire. The study was conducted using a completely randomized Fisher block design, with three repetitions over two years. The organic fertilizer «Bokashi» was applied in a crown around the cocoa trees at doses of 0, 2, 4 and 6 kg per year, corresponding respectively to treatments T0 (control), T1, T2 and T3. Soil samples were taken before and after the addition of Bokashi to assess the initial and final fertility of the soil. The average numbers of wilted cherelles, healthy pods, rotten pods, weight of fresh beans and actual and potential yields of cocoa trees fertilized with Bokashi were evaluated and compared to those of the control treatment. The collected data were subjected to analysis of variance (ANOVA) using SAS 9.4 software. The results showed that the addition of Bokashi improves soil fertility and the productivity of cocoa trees. The application of Bokashi also made it possible to reduce the levels of certain elements in the soil such as aluminum, which in very high quantities can be toxic for most plants. The highest actual (1351.05 kg/ha) and potential (1846.8 kg/ha) yields having been obtained with the dose of 2 kg of Bokashi per year and per cocoa tree therefore constitute the optimal dose allowing improve the chemical fertility of the soil and the productivity of cocoa trees.

A study on the mineral and liquid organics fertilizations was conducted on tomato (Solanum lycopersicum L.) during short rainy season in South and Central West regions of Ivory Coast over two years to improve soil fertility and tomato yield. specifically, the treatment effects of four doses of organic fertilizer, associated or not with the mineral fertilizer on the content of the soil organic matter, the C/N ratio and the yield. The experimental design was split-plot, with four repetitions having as principal factor, the mineral fertilizer and the secondary factor, the organic fertilizer in four doses (L ha-1): C0 = 0 (control); C1 = 2.5; C2 = 3.75 and C3 = 5. The results showed that the treatment T10 (50 % mineral fertilizer + 3.75 Lha-1 of the organic fertilizer), better improved the content of the soil organic matter and the yield. However, the treatment with 3.75 L ha-1 of organic fertilizer used alone has of increased advantage the report C/N of the ground.