The growth and yield of Acacia albida intercropped with maize ( Zea mays) and beans ( Phaseolus vulgaris) at Morogoro, Tanzania

Abstract

An experiment was conducted to evaluate the growth and production of Acacia albida under agroforestry at Mafiga, Morogoro, Tanzania. The design used was a split plot, in randomized complete blocks and replicated four times. Three main plots were included: (1) trees intercropped annually with maize, (2) trees intercropped annually with beans) (3) tree monoculture maintained under clean weeding. Each main plot was subdivided into four subplots representing different tree densities: (1) no trees, (2) trees planted at 4 m × 4 m, (3) 5 m×5 m spacing, (4) 6 m× 6 m spacing. At the age of 6 years, the A. albida was assessed for height, diameter growth, volume and biomass production. The mean height and diameter at breast height of the trees at this age were 8.4 m and 10.7 m, respectively. Height growth was not affected either by intercropping or by tree spacing, but diameter growth was significantly reduced at 4 m×4 m tree spacing. Volume production varied from 9.9 m 3 to 24.9 m 3 ha −1 and total biomass production from 12.4 to 28.3 ton ha −1. Intercropping did not significantly influence tree volume and biomass production. However, spacing significantly influenced productivity with higher values obtained under close tree spacing and lower production under wide spacing. Food crop yields were low, varying from 200 to 400 kg ha −1 for beans and 300 to 950 kg ha −1 for maize. The yields were, however, not significantly affected by the presence of the trees, even at the closest spacing of 4 m × 4 m.