The Oil Palm Nursery: Foundation for High Production:
Site
Selection
Ideally, the nursery
should be located on a level, well-drained area that is
easily accessible and close to the centre of the future plantation.
It is essential to have an
uninterrupted supply of clean water and topsoil which is both
well-structured and sufficiently deep enough to
accommodate three rounds
of on-site bag-filling. Approximately 35 ha
can grow enough seedlings
over a three-year period to plant a 5,000 ha
plantation.
Type of
Nursery
Double stage nurseries,
compared to a single stage nursery, are preferred because they require
less space and irrigation, and allow for
more efficient upkeep and
selection (culling). However, the double
stage nursery involves
transplanting pre-nursery seedlings to the main
nursery, which if done
improperly, may cause transplanting shock.
Each nursery should have
lockable stores for parts, tools and
equipment and for
chemicals and fertilizers (near a water supply).
Herbicides must be clearly
marked and kept separately from insecticides, fungicides, and foliar
fertilizers to prevent contamination and incorrect handling.
Pre-Nursery:
Materials, Preparation and Practice:
1. Pre-nursery seedling
beds, normally 10 m in length x 1.2 m in. width, hold 1,000 seedlings (100
x 10) planted in 250 gauge, black UV stabilized, 15 cm x 23 cm polybags.
Two rows of drainage holes are punched in the bags. Using the best
available hygienic soil, and after sieving it through a 5 mm metal screen
and amending it with phosphorus (P) fertilizer, bags should be filled to
within 2 cm of the rim. The fertilizer should be mixed thoroughly with the
soil to provide optimum P availability to the seedling’s root system. If
quality topsoil is used, no further manuring is required in the pre-nursery.
The filled polybags must be prepared four weeks before the seed arrives
and should be watered daily until planting to ensure adequate P
availability. Ranking and Fairhurst (1998) suggest the following planting
procedure: 1. Pre-germinated seeds received by the grower must be
kept under shade and cool. Once seed bags are opened, maintain moist
seeds by sprinkling them with distilled water.
2. The two-person planting
team should work as follows: The ‘seed handler’ places the seed on the
soil (which is about 2 cm below the top of the bag) with the root
(radicle) pointing downwards. The
‘planter’ positions the
seed correctly so that the shoot (plumule) is 1 cm beneath the surface
after covering the seed with soil and gently tamps and levels the added
soil with the palm of his hand.
3. Return the empty seed
bags containing the rejected seeds to the recording staff so they can
note seed quality.
4. Irrigate the seedlings
immediately after planting.
When ambient solar
radiation levels and very high mid-day temperature prevail, shade is
required for at least six
weeks, after which the
plants are exposed to increasing amounts of sunlight. Coconut or oil
palm fronds are often used for shade. Netafim has designed a shade house
which provides 40 percent shade for 100,000 plants within a 1,800 m2 area.
The shade house, measuring 120 m x 15 m, is constructed of metal (PTR)
uprights and steel lines to secure shade cloth. Columns at the centre of
the shade house are 3m high, and the two parallel steel lines are fixed 2
m above the floor.
Pre-nursery seedlings must
be watered daily. Whenever rainfall is
less than 10 mm per day,
irrigation is required, and the system must be
capable of uniformly
applying 6.5 mm water per day. The irrigation
systems most commonly used
overhead Micro sprinklers at about a 2 m. height, or Drip tubes
"CAPINET" attached to PE pipes on the surface to apply
fertigation when needed. Monitoring irrigation ensures complete and
adequate water and fertilizer application for each plant, insuring that each
plant will grow to it's maximum potential.
Avoids over-watering,
which can cause soil loss from the pots
and result in the roots of
the seedlings being exposed.
Weed control, if
required, must be done manually to avoid seedling
damage. The normal rule is
to not use herbicides in pre-nurseries.
Insect control is most
effective when pests are detected early and
treated promptly after
clear identification. In Mexico and other places,
the insecticide Carbofuran
(75 percent, 1 g per polybag) is used to control leaf-cutting worms, and
Metamidofos (49 percent, 3.75 ml per liter of irrigation water) is applied
for control of leaf insects.
Disease control may be
required in the pre-nursery, particularly
when hot and humid
conditions prevail. During the early stages of
development, the best
means for controlling leaf diseases is to reduce
excessive shade and ensure
adequate air movement. Preventive fungicide applications may start 25 days
after emergence and continue at intervals of 15 days. (Benomil 50 percent,
2.5 g/l; Captan 50 percent, 5g/l; or Clorotalonil 40 percent, 2 g/l water, are
commonly used.)
Transplanting
Pre-nursery seedlings in
the four-leaf stage of development (10 to
14 weeks after planting)
are usually transplanted to the main nursery,
after their gradual
adjustment to full sunlight and rigid selection
process. During culling,
seedlings with abnormal characteristics such as “grassy”, “crinkled”,
“twisted”, or “rolled” leaves should be discarded. In case of doubt, the
seedling should be removed.
Main Nursery
Pre-nursery seedlings are
transplanted into main nursery polybags
(i.e., 40 cm x 45 cm, 500
gauge, black UV stabilized) containing soil
prepared in the same
manner as for the pre-nursery. A 25 cm deep hole is made with a trowel or
a cylindrical core cutter in each main nursery polybag. The seedling is
transplanted after removing the pre-nursery polybag. Temporary shade
(e.g., nipah palm leaflet) and watering should be applied immediately
following transplanting to reduce transplanting shock.
Also, a 2.5 cm deep layer
of disease free mulch should be uniformly
spread around the seedling
soon after transplanting to prevent soil
erosion, to regulate soil
moisture and soil temperature, and to suppress
weed growth in the
polybag. Commonly used materials are oil palm
kernel shells, shredded
coconut fiber, rice husks, peanut shells, and coffee shells.
Manure and
Fertilizer Management
With the exception of P,
plant nutrient deficiencies can be corrected
through surface or foliar
application of fertilizer to transplants in the main nursery. It is
essential that the required amount of P (e.g., 300 g P2O5 per tone
of soil) be applied and mixed in the soil before bag filling.
Granular compound fertilizers are often used as they provide all
necessary nutrients in a single application. In Southeast Asia, the
two most frequently used compound fertilizer formulas are 15-15-6-4
[nitrogen (N)-P2O5-K2O-MgO)] and 12-12-17-2+micronutrients [N-P2O5-K2OMgO+ boron
(B), zinc (Zn), manganese (Mn) etc.]. As a general recommendation
usually is to apply 5 to 10 g 18-46 (N-P2O5) per seedling at weeks 3
and 6 after transplanting, followed by rates of 12 to 23 g
17-17-17 (N-P2O5-K2O) per seedling in 3-weekly intervals until week 30.
Table 1. N, P, K, and Mg
fertilizer nutrient application schedule for the main nursery (g per
seedling).
Weeks after
transplanting
N P2O5 K2O
MgO
1 0.8
0.8 0.3
0.2
3 0.8
0.8 1.2
0.1
5 1.1
1.1 0.4
0.3
7 1.2
1.2 1.7
0.2
10 1.5 1.5
0.6 0.4
13 1.2 1.2
1.7 0.2
16 2.3 2.3
0.9 0.6
19 1.8 1.8
2.6 0.3
22 3.0 3.0
1.2 0.8
25 2.4 2.4
3.4 1.3
28 2.4 2.4
3.4 1.3
32 3.0
3.0 4.3
1.4
36 3.0
3.0 16.3
2.0
40 3.0
3.0 4.3
2.0
44 3.6
3.6 5.1
2.0
48 3.6
3.6 5.1
2.0
52 3.6
3.6 5.1
4.0
56 3.6
3.6 5.1
5.3
Total
41.9 41.9
62.7 24.4
Table 1 provides
a generic, main nursery fertilizer schedule which can assist growers
in calculating fertilizer rates based on the types and sources of
materials available. Compacted ‘slow release’ fertilizer tablets
are expensive in terms of nutrient unit cost, and the benefits do not
justify general usage in the main nursery. Plastic spoons or measures
must be calibrated in order to apply the correct amount of fertilizer. The
fertilizer can be sprinkled in a circle around the seedling stem, ensuring
that it is not in contact with the seedling. To reduce risk of planting
shock, applications of fertilizer should cease one month prior to
field planting. At the same date, polybags should be rotated 180º
to sever all roots which may have penetrated the
nursery subsoil. The best method
of Fertilizer's application is through the Pot Drippers ("Capinet").
The fertilizer is applied in small quantity along with the irrigation water,
insuring exact and accurate application to each pot.
Weed
control:
Weeds growing in the
polybags must be
carefully pulled out.
Herbicides should not be used. If chemicals are needed, the products
Gramoxone and Diuron 80 WP
are preferred
for ground weed control,
but they should be applied with great care to avoid damage to seedlings.
Pest control:
Numerous insects (e.g.,
ants, armyworm, bagworm, aphids, thrips, mites, grasshoppers,
mealybugs) and vertebrates (e.g., rats, squirrels, porcupine,
wild boar, monkeys) are pests in oil palm nurseries and must
be carefully identified
before control measures are implemented. Product
advice should be sought locally.
Diseases afflicting seedlings and young plants are common in nurseries. The most prevalent among them are Blomerella cingulata, Botryodiploidia spp., Melanconium spp., blast, Curvularia blight, Corticum leaf spot, Helminthosporium, and spear or bud rot (Fusarium spp.). Begin prophylactic fungicide applications of Thiram 30 WP or similar fungicides when the seedling is in the sixth leaf growth stage. Curative sprays are applied once the disease symptoms appear and the disease is clearly identified. No known treatment cures plants suffering from foliar rot (Flecha-arguco), which is a disease that occurs in Mexico. Foliar rot begins with brownish lesions at the base of the leaf and progresses until it affects leaves in the crown of the plant. Since the casual agent is unknown, affected palms must be discarded and burned.
After 8 months in the nursery, normal healthy plants should be 0.8-1 m in height and display 5 to 8 functional leaves, with the middle leaves forming a 45º angle with the plant’s axis and leaflets spreading at an angle greater than 60º to the leaf rachis. At this time, a rigorous selection process should be started (Hartley, 1983). Abnormal seedlings will not produce an economic yield and must never be dispatched from the nursery for field planting. The most common disorders requiring seedling culling are:
• Flat top appearance.
