Vermicompost as an Alternative to Inorganic Fertilizer to Improve Okra Productivity in Côte d’Ivoire

Okra is one of the most popular vegetables in Côte d’Ivoire which is produced by heavy use of inorganic fertilizers. Vermicompost can be an alternative to inorganic fertilizers. This field study investigated the effect of vermicompost on growth and productivity of okra as compared to inorganic fertilizers. The respective treatments were arranged in a complete randomized block design, each at three replications, during three-season cycles on a ferralitic soil. Results showed that the highest rate of germination was obtained with the vermicompost. The tallest plants of Abelmoschus esculentus (1.88 m) and Abelmoschus caillei (1.78 m) were observed with inorganic fertilizer. The number of leaves per plant registered when using vermicompost was 34.5 and 30.74 with Abelmoschus esculentus and Abelmoschus cailli, respectively. With inorganic fertilizer, the number of leaves per plant was 34.21 (Abelmoschus esculentus) and 32.32 (Abelmoschus cailli). Plants took about 60 days to flower in the control plots and about 46 days in the plots fertilized with the vermicompost and the inorganic fertilizer. The highest pod yields of Abelmoschus esculentus and Abelmoschus cailli were 8.7 t⋅ha−1 and 10.58 t⋅ha−1 with vermicompost and 8.85 t⋅ha−1 and 10.7 t⋅ha−1 with inorganic fertilizer, respectively. Vermicompost could be recommended as an alternative to inorganic fertilizer to produce okra on ferralitic soil in Côte d’Ivoire.

Incorporation of Crop Residues into Soil: A Practice to Improve Soil Chemical Properties

Crop residues have the potential to enhance soil fertility, but this is dependent on their biochemical properties. This study aimed to evaluate the chemical composition, and nutrients release patterns of selected crop residues (corn stalk, rice straw, millet straw and sorghum stalk). Thus, 20 g of each crop residue were put in litter bags and placed in a plastic pot containing 10 kg of soil with a moisture content of 40% - 60%. Five replications were considered per type of residue and some samples were taken every 4 weeks. Results showed that crop residues got a pH varying between 5.09 and 6.5. The lowest C content (33.11%) and nitrogen (0.27%) were measured in sorghum stalk when the highest C content (47.6%) and nitrogen content (0.55%) were registered in corn stalk. The highest phosphorus content (0.58%) was got in corn stalk. Potassium content was higher in millet straw than in others. The highest calcium content (0.37%) and magnesium (0.29%) were found in rice straw. There was an increase of soil chemical composition after crop residues burial. Significant increase in carbon, nitrogen, and phosphorus content was noted in soil at week 4 with the highest at week 16. At the end of the experiment, the highest C content (53.1%) and the highest nitrogen content (0.88%) in the soil were observed after burial of rice straw. The highest phosphorus content (0.82%) registered in the soil was got with millet straw. Nutrient release efficiency of crop residues occurred in the following order: rice straw > millet straw > sorghum stalk > corn stalk. This study has demonstrated that rice straw and millet straw released nutrients faster and this is beneficial for early planted crops, while sorghum stalk and corn stalk released nutrients slowly which is appropriate for long-term availability of plant nutrients.