In Côte d’Ivoire, the sweet potato is little cultivated but stays however a culture of pension and a food mattering in certain regions. This study was conducted to assess the effect of the application of mineral (NPK 15-15-15, NPK 12-22-22) and organic (poultry manure) fertilizers on yield components of sweet potato (Ipomoea batatas (L) Lam). The experiment was conducted over two years (2016 to 2017) in experimental station of National Center of Agronomic Research (CNRA) of Bouaké in the centre of Côte d'Ivoire. The experiment was conducted following a split plot with 2 factors (variety and fertilizers) and 3 replicates. The main factor was variety with 2 levels (variety Irene and variety TIB-440060) and the subplot was fertilizers application consisted 13 levels (200, 300, 400, 500 kg ha-1 of NPK fertilizers combined 5, 10, 15 t ha-1 of organic fertilizer). Thirteen treatments based on poultry manure (T6, T7), chemical fertilizer NPK 15 15 15 (T1, T3, T4, T5) and NPK 12 22 22 (T8, T10, T11, T12) and their combination (T2 and T9) were tested. The experimental results revealed that that the effects of chemical fertilizer treatments, manure and their combination with mineral fertilizers did not influence the measured parameters. The results also showed that fertilizers improved all the agronomic parameters of sweet potato compared to the control treatment during two years of experiment. However, the Irene variety with a mean weight of 180 g tuberous roots was significantly different from the TIB variety with a mean weight of 138.73 g. In the conditions of our study and over the two-year period, producers of sweet potatoes would benefit from using organic fertilizers with the Irene variety.

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Abstract:In a completely randomized blocks (RCB) plot, we planted seed from the three segments of Kponan tubers: head, median and tail portions with control Krengle. Germination began 10 d and lasted 67 d. The mean sprouting rate of the Kponan full season harvest tuber was 78.1% compared to 94% in Krengle. However, the tuber germination was progressive from head to tail with a linear evolution of the top fragments with sprouting rate up to 90% similar to Krengle. The median and distal portions sprout two and three weeks later with final raising rates reaching 68% and 71%, respectively. The full season tuber of Kponan sprouts with a good rate gave good yields for any portion of the tuber. It had a sprouting gradient oriented from the proximal portion to the distal one, while yield was better for medium seeds. The sprouting delays two weeks between proximal and medium portions and three weeks between proximal and distal portions were acceptable with regards to the total cycle of eight to nine months period. Thus, its small tubers could be planted as well as the top portion of big tuber. In terms of yield, Kponan medium seed gave the best yield 34.25 t/ha and the whole Kponan tuber yield was more than Krengle. That led to a better multiplication factor for Kponan full season tuber. The type of tuber, if available, could be used as seed for yam production. That could improve its distribution and contribute to food security.

The objective of this work is to improve the production and yield of cassava cultivated by tillage. The experiment was conducted in the field for 13 months (June 2019-july 2020) in Abongoua in the department of Bongouanou (East-central Côte d'Ivoire). After the cleaning of a 900 m2 surface of a fallow of more than 5 years, and cleared of all plant debris, soil samples were taken with an auger in the 40 cm surface in each corner and in the center of the experimental plot to constitute the composite sample for laboratory analysis. The trials were conducted in a randomized complete block design with four replicates in which four elementary plots were distributed. Three treatments T1 (tilled soil), T2 (mounded soil) and T3 (ridged soil) compared to a control treatment T0 (no-till soil) were applied in each microplot. The cuttings were directly sown at a rate of 12 cuttings per treatment. The data of the different parameters collected underwent an analysis of variance (ANOVA) performed with SAS software version 9.4 and the means were separated using the Newman and Keuls test at the 5% probability threshold. The results showed an acidic soil with a sandy texture and a good supply of nutrients, particularly major elements, trace elements and clay-humus complex. Good growth and development of agro-morphological parameters as well as yield were obtained with treatments T3 (ridged soil), T2 (mounded soil) and T1 (tilled soil) in decreasing order of importance compared to the control treatment (T0). In conclusion, the study clearly showed that the type of tillage, particularly the ridged tillage technique, improves the agro morphological parameters, productivity and yield of cassava. What we recommend to farmers for a good yield of cassava in the area.

This study was carried out to investigate the relationship between earthworm trophic groups and soil morphology and chemical attributes, and moreover, to determine which of these attributes would be most significant in explaining the distribution of earthworm communities in agro-ecosystems in the Centre-West region of Côte d'Ivoire. Earthworms' soil morphology and soil samples were studied in three agro-ecosystems: 20-year-old cocoa plantations, 5-year-old mixed cocoa plantations and mixed crop-fields. The semi-deciduous forests near the agro-ecosystems were also sampled and considered as control plots. Earthworm global densities varied on average between 53.9 ± 7.9 and 86.0 ± 19.0 individuals m −2 and biomass between 16.5 ± 3.1 and 20.6 ± 4.1 g m −2 under these ecosystems. Path analysis produced a significant model: soil morphology and chemical attributes under different agro-ecosystems affected the density and biomass of earthworm trophic groups, and these attributes are potential regulators of the fauna communities. The morphological components related to dead leaves (r 2 = 0.73, P < 0.05) and fine woods quantities (r 2 = 0.71, P < 0.05) are most decisive for detritivore abundances, whereas geophageous mesohumic abundances were positively affected by soil organic carbon (r 2 = 0.79, P < 0.05) and N (r 2 = 0.84, P < 0.05) and geophageous polyhumic abundances were positively affected only by soil N (r 2 = 0.63, P < 0.05). In agro-ecosystems the relationship between soil conditions and earthworm communities varied between earthworm trophic groups, so detritivores were more affected by litter quantity, whereas shallow geophageous populations were guided by soil organic matter.