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.

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.

To assess the influence of Jatropha curcas cultivation on maize yield in a cropping association, a study was conducted on the application farm of the Ecole Régionale d'Agriculture du Sud in Bingerville from 2015 to 2016. The study aimed to determine the appropriate Jatropha planting density to improve maize yield in a cropping association. The experiment consisted in setting up a randomized complete block design with three replications, including three treatments T1 (2*2m); T2 (3*2m) and T3 (4*2m) based on the spacing of Jatropha curcas plants compared to a control T0 (control without jatropha). Morphological and yield parameters of Jatropha curcas and maize were assessed respectively. The results obtained show that the Jatropha-maize association had no significant effect (P > 0.05) on the agro-morphological parameters (growth, development and yield) of Jatropha curcas regardless of the treatment. On the other hand, a significant effect (P < 0.05) of the Jatropha-maize association was observed on plant biomass and maize yield, particularly with treatment T2. In conclusion, this experiment demonstrates that it is possible to harmoniously integrate regular row spacing (intercropping) in Jatropha curcas plantations during the juvenile period of the trees provided that the main crop (Jatropha curcas) is at a spacing of 3*2 m.

The high price of chemical inputs has led producers to use other sources of fertilizer such as chicken manure. However, the direct and compost-free application of these wastes as practiced by producers is a potential source of soil acidification and environmental contamination that cannot adequately restore soil fertility. The objective of the study was to evaluate the effects of composting times on the chemical fertility of the composts produced. The study was carried out at the Jean Lorougnon Guédé University in the Tazibouo district of Daloa, in the centre-west of Côte d'Ivoire. Twelve (12) piles of chicken manure were made up of 3 piles per treatment corresponding to the different composting times (T14, T21, T28, T35 days). Four treatments rated T14, T21, T28 and T35 corresponding to 14, 21, 28 and 35 days of composting of the feces were compared to a control treatment T0 (composted chicken feces). The study found that composting chicken manure has positive effects on its chemical fertility by improving the levels of most of the physical and chemical parameters of the composts produced. As a result, composting has reduced concentrations of trace metal elements, such as iron and zinc, in composted chicken droppings, which at high soil levels become toxic to plants. Composting the manure for 14 days by improving the fertility of the composts produced can therefore be recommended to growers for a better chemical quality of the compost produced.

This study is focused on the soil morphological and physico-chemical characteristics of soils influenced by the topographical factor in Savanna area. It was carried out along three toposequences in Gogbala area of Korhogo Department, Northern Côte d'Ivoire. Soil samples were collected at each topographic unit, namely, upper slope positions, mid slope positions and bottom slope positions. Samples collected were air-dried, crushed and sieved in a 2 mm sieve preparatory to laboratory analysis. The results showed that Cambisols are the dominant soils in the study area; these are characteristic soils of reddish brown (2.5YR 4/6) to yellowish brown (10YR 4/2) at the upper and mid slope positions, and grey (10YR 5/1) at the lower slope positions. These are well drained soils whose genesis is considered to have been predominantly influenced by climate in which they occur. The profiles are weak fine granular transformation and evident changes in soil structure, color and clay content. They are dominated by sandy loam textures. Organic matter and N, available P, Exchangeable Ca, Mg contents, CEC are in the range of low to medium values. The pH values of the samples are acid (pH < 6). Fertility is low. Therefore, to perform agricultural managements in Gogbala area, decision-makers should take into soil morphological and physico-chemical characteristics consideration, suggest the need of integrated nutrient management with addition of both organic and inorganic fertilizers in the land units.