Abstract:
Agroforestry is the set of land-use practices involving the deliberate combination of trees,
crops and/or animals on the same land management unit in some form of spatial arrangement
or temporal sequence (Lundgren and Raintree, 1982). The trees have been used for fuel wood,
charcoal, shade, fodder, soil fertility maintenance and fencing. This study was conducted to
assess the effect of Faidherbia albida and Acacia tortilis on grain yield of wheat and above
ground biomass and soil physico-chemical properties at Langano and Tuka in farm fields of
Bora District where both trees are traditionally retained on the farm. At each site, four
Faidherbia albida and four Acacia tortilis trees were purposively selected and soil sample
collected from four directions at three distances (1.35 m, 3.35 m and 26.35 m) from tree trunk
and composite soil samples was taken for both physic-chemical analyses. As well as average
grain yield and biomass taken from each distance were compared between each distance.
Collected was analyzed by two way ANOVA and mean separation with LSD (%). Results
indicated that recorded grain yield and biomass yield showed significant difference (p < 0.05)
and were significantly greater under canopy of both trees at both locations compared to the
open land. Mean moisture levels of all sites 1.35 (14.319%) were significantly (p < 0.05)
greater than openland (10.795%) at 26.35 m from tree trunk. Bulk density was also
significantly affected by tree canopies (p<0.05). It was increased from 1.201 g/cm3 under
canopy to 1.286 g/cm3 in the openland. Soil textural distribution (sand% silt% and clay%)
was not significantly affected (p>0.05) by distance from trees. At both sites, pH was
significantly lower (p < 0.05) under the canopy than out of the canopy (it was lowered
from 6.05 under canopy to 7.00 at open land). Soil organic matter, total nitrogen available
phosphorus, exchangeable calcium, exchangeable magnesium and cation exchange capacity
were significantly higher (p < 0.05) under the canopy of trees compared to openland. Apart
from these, the recorded values of exchangeable sodium, potassium and electrical
conductivity revealed statistically non-significant difference among the treatments. In general
the two trees showed increment of wheat yield and selected soil physico chemical properties
under their canopy as compared to the open land
