Evolution of maize yield after tree fallow in a humid forest zone of Côte d'Ivoire | Evolution du rendement du maïs après une jachère arborée en zone de forêt humide de Côte d'Ivoire
2002
N'Goran, A. ((Centre National de la Recherche Agronomique, Abidjan (Côte d'Ivoire). Station Marc-Delorme)) | Gnahoua, G.M. | Oualou, K. | Balle, P.
In the humid forest zone of Côte d'Ivoire a fallow dominated by Chromolaena odorata was enriched in 1987 with Acacia mangium, Acacia auriculiformis, Albizzia lebbeck and Leucaena leucocephala. The area has a bimodal rain-fall pattern, with a mean annual rainfall of 1,089 mm between 1991 and 2000. In 1993, the trees were felled and 7 cycles of maize were conducted on the plots from 1993 to 1996. Experiments were conducted in a factorial trial with three factors studied: the previous farming including five modes: the natural fallow (JN) = control, fallows of Acacia mangium (AM), Acacia auriculiformis (AA), Albizzia lebbeck (AL) and Leucaena leucocephala (LL), the litter management including two modes (mulch or burnt) and the fertilisation with two modes (with or without chemical fertilizer). After six years, the soil nitrogen content of all fallows was superior to 1.5 o/oo, the richest being Albizzia lebbeck, followed by the Leucaena leucocephala fallow and control. Whatever the year and the cultural cycle, maize yield in fertilised plots was always higher than without fertiliser. When effects were significant the Acacia auriculiformis fallow gave lower yield than with the other previous farmings). The fallows of Acacia mangium, Albizzia lebbeck, Leucaena leucocephala and the natural fallow gave similar yields. A significant interaction was noticed between litter management and the fertilisation in 1993 for the first cycle (mulch + fertilisation) was superior to (burnt + fertilisation). Maize grain yield decreased gradually from 1993 to 1996, whatever the fallow and whether fertilizer was used or not
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