| dc.description.abstract | The influence of Plectranthus barbatus live fence and
GreviIlea robusta trees on soil moisture and crop
production was explored for two growing seasons
(October - January 1990/91 and March - August, 1991)
at Matanya, Laikipia District, Kenya. Two experiments
were set up separately for the live fence and trees.
There were two management practices; root pruning and
no pruning (30 cm deep and 40 cm away from the
live fence and trees).
Soil moisture was monitored at three distances away
(94 cm, 188 cm and 375 cm) from the live fence/trees
using a neutron probe upto 170 cm deep. Grop
performance and product ion for maize and beans
intercropping were evaluated row-wise in the
live fence and at four distances radially from the
trees.
In the unpruned live fence experiment, in the first
season maize biomass production at the third and
fourth rows was significantly different (at 5 %
level) from the first and second rows. The comparison
of the pruned and unpruned live fence plots showed
that maize biomass production in the the first season
was 147 %, 59 % and 5 % higher in the first three
rows of the pruned plot from the first three rows of
the unpruned plot.
During rainy periods available soil water within 45
cm depth was higher at 375 cm away from the live fence
by up to 37 % and 100 % than at 188 cm and 94 cm,
respectively in the unpruned plot. Furthermore up to
65 % (at 94 % cm) and 20 % (at 188 cm) higher
available soil water was monitored in the pruned plot
. than the unpruned plot. However during dry periods
probably evaporation (at 375 cm) compensated root
competition for moisture (at 94 cm) and thus there
was no difference between treatments. In general it
could be said that competition for moisture could
reach up to the second row of maize (188 cm).
The investigation in the tree experiment has shown
that crop performance and product ion were not
significantly different between the four distances
and between the two management practices. Pruning has
not proved to be beneficial in terms of increasing
yield by reducing root competition for moisture.
Comparison of the tree system with the local and
mulching methods proved that the system used soil
water that would otherwise have been lost as deep
percolation, without reducing the crop production.
Thus the overall productivity of the system was
better than the local and mulching methods. | en |
