Typology of Crop Residues and Energy Recovery in Heavily Agricultural Areas: Case of the Departments of Soubré, Daloa, Issia and Sassandra (Côte d’Ivoire)

The valorization of crop residues could constitute an energy source (biogas) allowing to reduce the energy needs of populations in agricultural regions, improve their living conditions and slow down deforestation as well as greenhouse gas emissions. This work aims to determine the typology of agricultural waste in the departments of Soubré, Sassandra, Daloa and Issia, to determine the number of residues generated in these departments, and to assess the biogas potential of these departments said residues. Field observations were made to identify the different types of waste, then, based on agricultural statistical data from the Ministry of Agriculture and biogas productivity indexes, the quantities of agricultural residues and biogas were estimated. Agricultural residues consist of pods (50%), stalks (19%), cobs (3%), Straws (8%), stalks (2%), shells (9%), fibers (7%), husks (1%), and bunches (1%). In addition, these localities have 465266.3 t of pods, 173583.2 t of stalks, 84280.0 t of shells, 75,857 t of straws, 12,000 t of husks, 10,987 t of bunches and 6793.0 t of fibers. The departments of Soubré, Sassandra, Daloa and Issia contain a total potential energy of 235.87 × 106 m3 of biogas. However, this is unevenly distributed among the localities. The volume of biogas recorded is higher in the department of Soubré (74.91 × 106 m3) which is followed respectively by the departments of Daloa (62.27 × 106 m3), Issia (52.77 × 106 m3 and Sassandra (45.93 × 106 m3). The departments of Soubré, Sassandra, Daloa and Issia have a very large potential for the production of agricultural residues that may be of interest to economic operators for recovery in biogas production units.

Assessment of the Natural Landscape Changes Due to Cashew Plantations in the Department of Niakaramandougou (North of Côte d’Ivoire)

In the past twenty years, C?te d’Ivoire has risen from being an insignificant producer of raw cashew nuts to becoming the world’s largest producer. A rapid increase of cashew plantations has significantly changed the natural landscape in the North part of C?te d’Ivoire. This study was conducted in the department of Niakaramadougou to assess the natural landscape change due to cashew plantations from 1989 to 2017. Satellite image data were used in order to evaluate land use land cover (LULC) change. The maximum likelihood pixel-based on classification method was used to analyze the spatio-temporal LULC dynamics for the years 1989, 2000, and 2017. The results showed an increase in cashew culture by 20.68% between 1989 and 2017 to the detriment of the savannah. Thus, the land devoted to old fallows or to other crops such as rice, maize, yams, peanuts, sorghum) is decreasing and the natural vegetation is becoming more and more fragmented, with consequences that are not yet known. This surely contributes to the reduction of plant diversity.