Effect of Acacia senegal on growth and yield of groundnut, sesame and roselle in an agroforestry system in North Kordofan state, Sudan

Two field trials were conducted under rainfed conditions at El-Obeid Research Farm and Eldemokeya Forest Reserve, North Kordofan State during the growing seasons 2004/2005 and 2005/2006. The objective was to investigate the effect of Acacia senegal on the performance and yield of groundnut (Arachis hypogea), sesame (Sesamum indicum) and roselle (Hibiscus sabdariffa) in an agroforestry system. The two trials consisted of seven treatments: three represented the intercropping of groundnut, sesame and roselle with A. senegal, three without trees and one represented A. senegal alone. Data were recorded on soil physical and chemical properties, soil moisture content, crops fresh weight (kg/ha), dry weight (kg/ha), gum yield (g/picking) and crop yield (kg/ha). The trees at El-Obeid yielded no gum, whereas those at Eldemokeya were 15 years old and were tapped as part of the total harvest in the agroforestry plots. Land equivalent ratios (LER) and simple financial analyses of gross surpluses were used to evaluate the productivity of the different treatments. Fresh weight of groundnut, sesame and roselle was significantly different (P < .0.05) at both sites. Higher fresh weights were found under the intercropping system than the sole cropping system. This could be attributed to a shading effect that limits fruit production of the field crops more than vegetative growth. Dry weights were significantly greater for sesame and roselle in both sites, while that of groundnuts was not significantly different. In both sites, intercropping reduced the yield of sesame by 6 and 11% in the first season and 37 and 39% in the second season. The reduction in roselle yield was 19 and 28% in the first season and 15 and 8% in the second season. Yield reduction in groundnut was 35 and 17% in the first season and 35 and 11% in the second season. The combined analysis indicated that intercropping reduced groundnut yield by 26%, sesame by 21% and roselle by 20%. All the treatments gave LER of more than one—indicating the superiority of growing the field crops in intercropping over the sole cropping systems. The highest LER of (1.71) was obtained when roselle was intercropped with A. senegal, while the lowest LER (1.48) was obtained when groundnuts were intercropped with A. senegal. All the treatments gave positive net revenues, the highest being for intercropped roselle (438 SDG/ha). The intercropping of sesame gave the second highest net revenue (387 SDG/ha), while the sole roselle gave the lowest net revenue (97 SDG/ha).