Abstract

The effect of Acacia seyal tree on soil bulk density, soil moisture content, grain and biomass yield of tef (Eragrostis tef) were examined on six selected comparable A. seyal trees on croplands. Composite soil samples (6 trees × 3 distances × 2 soil depths) were collected at three distances from the tree base (1, 2.5 and 9 m) and two soil depths (0-15 and 15-30 cm) in four radial directions. Grain and biomass yield of tef were also sampled from 1 m2 plot at the three distances from where the soils were sampled. The result indicated that soil bulk density (BD) and soil moisture content (SMC) were significantly affected both by distance from the tree base and soil depths. Grain yield of tef and SMC was higher whereas BD was lower under the canopy of A. seyal than that of beyond the canopy. The reduction of grain and biomass yield at the nearest distance may be attributed by competition for light and water between tree and crop. However, biomass yield of associated tef were the same under the canopy and away from the canopy of A. seyal. Therefore, the result indicates that retaining of A. seyal tree on croplands with the integration of food crops, could be an additional benefit for the farmers without competing their crop production.

Key words: Acacia seyal, soil physical property, biomass, grain yield of tef.