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A S'roDY OF AILEY
LEUCAENA ~
((
CHOPPING MAIZE AND GREEN GRAM WITH
(LAM) DE WIT AT MI'WAPA, COAST PROVINCE,
KENYA
BY
A Thesis submitted in partial fulfilment of the
requirements for the degree of
MASTER OF SCIENCE
IN
AGRONa1Y
r
at the
UNIVERSITY
OF NAIROBI
Faculty of Agriculture
1988
UNlVBRSITY OF NAIRa
lFlRARY
(xiii)
ABSTRACT
Crop
yields
in
the
Kenya
Coastal
lowlands
are low because of poor soil
fertility and high weed infestation.
The sandy soils (92%
in
are
all
major
nutrients
N,P,K,
highly
sand),
leachable
deficient
and" fertilizer
application is necessary for good crop yields.
Green' leaf
Manure
established in
a
(GlM)
from
split-plot
Incorporat.ed to
Leucaena
systematic
made
design
with
hedgerows
(alleys)
5-replications
were
boost soil fertility, by cutting them down to O.5m from the
ground level 2 weeks before maize crop
were
leucocephala
during
the
cropping
planting.
season
Two
additional
cuttings
for additional GUM and to minimize
Leucaena shading on the crop.
Assessment of crop
yields
carried
a period of four years (1982-1985).
out
the usual
over
trend
of
continuous
cropping
The system
was
continuous
cropping
soil
was
even
pruning during which
and
monitoring
fertility
reversed
able 'to
years,
crops
of
decline
with
increase
soil
that
fertility
trends
was
It was observed that
normally
results
with
the use of Leucaena alley farming.
maize
yield
by
38%
after
four
except for the period of tree establishment and
were
significantly
reduced
due
to
excessive
shade effect.
Soil
tests
also
showed
a
gradual
increase
phosphorus, potassium, calcium, magnesium and pH
This
was
due
to
the
high
organic
in
soil
over
the
N-additions , up
Leucaena GlM, nutrients release from tree root death and
finally,
the
tree
nutrients
savings
density/ha,
the
from
uptake
by weeds.
higher
the
concentration
including an increase in soil pH.
%
to
organic carbon,
control
plot's.
283Kg N/ha from
decomposition,
and
In general, the higher
of
soil
nutrients
(xiv)
Significant
weed
cqntrol
of upto 90% was achieved due to the fallow effect
preceding the alley cropping.
grass
weeds
were
reduced
Besides, most
of
the
difficult
to
in favour of the easier to control broad-leaved,
non-grass weeds.
The Financial
returns
and
savings
fuelwood
GLM
the
system
and
to
control
from
were
the
also
sale
and
remarkably
use
of
high.
cuttings during one cropping season yielded 28.3 t/ha of fresh GLM.