TROPSOIL'J
PUSLITTAN
WEST SUMATERA
TROPSOILS Indonesia / Center for Soil Research
Field Research Brief No. 20
October 1985

TITLE: Alley Cropping Trial Tree Establishment Period

EXPERIMENT NO.: 3502

RESEARCHERS: Carl Evensen and Russell Yost

OBJECTIVES: 1. To determine N, leaf, and wood production and Al
tolerance of three legume tree species under
Sitiung conditions.
2. To measure the effects of green leaf manure
additions on rice and soybean (or cowpea) yields
(intercropped with the trees).
3. To measure effects of these organic matter
additions on soil chemical properties (Al
saturation, ECEC, pH, organic C, etc.) and their
interactions with crop growth.
4. To select an appropriate legume tree species and
liming level for farmer testing.

SOIL: Typic Paleudult; clayey, kaolinitic, isohyperthermic.
FCC: Ceak. Cleared by manual tree felling and then
bulldozed during 82/83 wet season but never cropped;
heavily eroded in parts.

EXPERIMENTAL DESIGN:
The experiment is laid out in a split plot design with four
replications. The treatments are as follows:

Main Plots Tree Species
1) Albizia falcataria (planted by seed)
2) Calliandra calothyrsus (planted by seed)
3) Gliricidia seeium (planted by hardwood cuttings)
4) No trees (control)
Subplot Liming Levels
1) No lime
2) Low lime (Ca supplied as a nutrient at 375 kg CaCO3/ha/
year to provide 0.5 meq Ca/100g soil to 15 cm depth)
3) Liming rate to reduce .Al saturation to 25 %
(2 T CaCO3/ha during first year)


CROPS:
This report covers the first crop of upland rice and the
second crop of cowpeas, which were planted during the establish-
ment phase of the alley cropped trees. The lime rates were
broadcast over the subplots on December 22, 1984 along with a
blanket application of P at a rate of 40 kg P/ha. To establish
the tree hedges, TSP was applied at 10 g/m in 25cm wide strips
(to provide 80 kg/ha of P in the 25cm wide strips). The trees







were planted in hedgerows over the fertilized strips on December
29 and 31, 1984. Subplot size is 5.5m x 12m (consisting of 3
hedges, 5.5m long and 4m between hedges) for the alley cropped
plots and 5.5m x 6m for the no-tree control plots. The harvested
portion of the subplots consists of the central 3m of the center
tree hedge and 2m to either side of the hedge (ie. 12 m2) for
food crop yields. Plots were laid out to exclude stumps, soil
mounds, and tree throw holes, where possible.

Upland rice ('Sentani') was planted on January 12, 1985 at a
25 x 25cm spacing, skipping one row of rice where there was a row
of trees. Furadan insecticide was applied in the dibble hole at
about 1.5 kg a.i./ha. Germination was delayed by dry weather, but
a good stand resulted from rains two weeks after planting. N was
sidedressed at 25 kg N/ha at 42 days after planting. However,
rice blast began to appear at about this time and became so
severe that almost no grain was produced. The crop was harvested
for total plant weight on May 13 and 14, 1985. The alley cropped
trees were quite small and were not expected to affect rice
yields at this time, however, a liming effect as well as extreme
soil microvariability were observed (as reflected by rice plant
heights and leaf color). The zero lime subplots were extremely
stunted and chlorotic.

A semi-determinate local variety of cowpea was planted on
May 17, 1985 at 20cm intra-row x 40cm inter-row spacing. No rows
of cowpeas were skipped in subplots with trees (ie. rows of
cowpea were planted 20 cm on either side of the tree rows). No
additional fertilizer was applied, so that soil microvariability
could be further characterized. Sevin insecticide (85%
carbamate) was applied 15 day after planting at 0.5 kg a.i./ha.

Germination was excellent, but within two weeks, plots
without lime had extensive leaf chlorosis and necrosis and about
30 to 50 % seedling mortality. At both low and high lime rates,
plants were fairly healthy, although throughout the experiment,
many plants exhibited leaf bronzing and purplish-brown mottling
along the veins. This might have indicated a general K
deficiency, Ca deficiency, and/or Al toxicity, since it was much
worse in the unlimed subplots. The alley cropped tree species
were much more vigorous by this time and, especially in the case
of the Albizia, competed for light with the cowpeas. However,
there was a prolonged drought from mid-June to late-July which
severely reduced pod set and yields. Thus, when cowpeas were
harvested on September 12, only total plant weights were measured.


RESULTS:

Total plant dry matter yields and plant heights in the
upland rice crop showed a highly significant response to lime.
There was no significant difference between the low and the high
rates of lime (Table 1). There was also no rice growth response
to the tree species, since the trees were too young to compete
with the rice and had not yet been trimmed for green manure.







Table 1. Upland rice response to liming.


Lime Rate


Dry Matter Yield


Plant Height


(kg7Tha) (kg7ha) (cm)

375 2005 50

S2000 1667 46

0 940 32

LSD (0.05) 620 9


An analysis of variance for the cowpea total dry matter
yields indicated that tree species had a significant effect (0.05
level) and liming rates had a highly significant effect (0.01
level) on cowpea yields. In Table 2a, cowpea yields are shown to
be significantly increased by lime application, although the low
and high lime rates produced the same yields. This supports the
earlier observation in the upland rice crop that 375 kg lime/ha
is sufficient for Al tolerant crops on this soil. In Table 2b,
the Albizia hedge rows significantly decreased cowpea yields
(undoubtedly through shading, since the Albizia trees averaged 3 to
4 meters in height by cowpea harvest). The other trees did not
significantly differ from the no tree control in effects on the
cowpea crop. This competition of trees intercropped with food
crops will not subsequently be so severe since tree hedges will
be cut to a 40 50 cm stubble every few months during the
cropping season. Also the application of the green leaf manures,
starting in September, will presumably more than compensate for
any tree/food crop competition. More timely planting, to reduce
blast infection and experience better soil moisture conditions,
will hopefully, also improve on the dismal yields found in these
first two crops.


Table 2.

Lime Rate


Total dry matter yield of cowpeas (vines and pods) in
response to liming (a) and alley cropped trees (b).


Dry Matter Yield


Tree Species


Dry Matter Yield


(kg7ha)- (kg/h a)

2000 216

375 215

0 73

LSD (0. 05 92~


(kg7ha)

No Tree 256

Calliandra 189

Gliricidia 175

Albizia 49

LSD (0.05) 118

(b)


(a)