| dc.description.abstract | A study was carried out in Machakos district,
Kenya, to investigate the competition for soil
moisture in an alley cropping agroforestry system.
The effects on soil moisture and crop yields of
Agroforestry (AF) and Non-agroforestry (NAF) systems
was evaluated in two growing seasons (Experiment 1
and 2). The AF system involved alleys of a perennial
shrub, Cassia siamea Lam. and between them a crop
Zea mays L. var. Katumani composite B. The AF
system
lopped
plots were mulched with leaves and twigs
from the Cassia hedgerows just before
planting.
Below
The NAF plots were not
ground interaction
mulched.
was determined by
measurement of soil moisture using the gravimetric
method. The soil was sampled using an auger, at
four points of 45cm interval from the hedgerow and
three depths for every point, respectively.
Measurements of stomatal resistance, transpiration
rates and leaf-air temperature difference were used
as above ground indicators of competition for soil
moisture, and therefore water stress. These were
measured everyone or two weeks.
The influence of distance from Cassia hedgerows
on soil moisture did not prove significant for the
first
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five measurements of experiment 1 and for the
entire set of measurements of experimend 2, for all
depths. There was no interaction between AF system
and distance or depth.
Stomatal resistance of the middle maize row (MMR)
was not significantly different from that of the
border maize row (BMR) in the AF system for both
experiment 1 and 2, respectively. Stomatal
resistances of the AF system maize plants were
generally lower and in some cases also statistically
significantly different from those of the NAF system
maize plants for both experiments.
Transpiration rates of maize within the AF system
showed statistically insignificant variation between
the MMR and the BMR. AF system maize plants
showed generally higher transpiration rates than the
NAF maize plants, which were again in some cases even
statistically significantly different.
Leaf-air temperature differences of the MMR were
not significantly different from the BMR in the AF
system for both experiments. Appreciable differences
were also not detected between AF and NAF systems for
both experiments.
Maize yield was not suppressed by proximity to the
Cassia hedgerows. On the contrary, the grain and
cob weights of the BMR were on the average
significantly higher than those of the MMR for both
- xx -
experiment 1 and 2 probably due to a combination of
factors such as soil temperature variation and
differences in root overlapping. Maize in the AF
system performed better than in the NAF system for
both experiment 1 and 2, due to various improved
conditions.
The study showed that competition for soil
moisture between Cassia and maize was not
significant. This will have been due to the above
average
period. | en |
