Field Cultivation Techniques
• Choice of plot
When choosing a production site for okra, a well-ventilated location should be preferred to ensure proper aeration of the vegetation. Properaeration reduces ambient humidity in the field thereby diminishing the risk of certain fungal diseases developing such as Cercospora Leaf Blight.
Furthermore, areas where there is too much shade over the field or ones where heavy dew occurs should be avoided because this maintains a highdegree of humidity in the plants that fosters fungal disease development. Hence, okra should not be grown in poorly ventilated, heavily shadedforest areas.
• Rotation
For best results in okra production from a plant health viewpoint, and mainly to avoid big losses due to root-knot nematodes, it is advisable to implement appropriate crop rotation methods. Indeed, no Malvaceae (sorrel, okra, cotton) should be cultivated in succession on the same plot for two to three years. Okra can come after amaranth, mint, daikon, corn, onion, radish and digitaria- or panicum grass-based fallow. Since root-knotnematodes are a major problem in many growing areas, the following crops must not be included in a rotation with okra: tomatoes, karella, brinjals (eggplants), pawpaw, bananas, capsicums, potatoes, squash and sweet potatoes.
• Cropping history
To avoid a number of fungal or viral diseases as well as nematode infestation, okra should not be grown on soil where previous crops were planted that belong to the Cucurbitaceae, Solanaceae or Malvaceae families.
• Adjacent crops
It is not advisable to grow okra close to fields where other plants in the family of the Malvaceae such as cotton, roselle, are grown. This is intended to prevent flea beetles and other insects or diseases these plants share with okra from moving to the new crop. It is also preferable to avoid the vicinity of crops that are highly susceptible to Aphids gossypii (cucumber, melon, eggplant) and to jassid (eggplant, etc.).
• Preparing the Soil tests
Prior to preparing the soil for okra culture, it is highly advisable to conduct soil tests so as to examine its structure, texture, physical and
chemical composition, pH and microbiological profile (nematodes, fungi responsible for damping off). These tests are helpful in deciding on dressings to correct the pH, the required quantities of base dressing, type of preventive plant protection treatment on the basis of okra culture requirements.
Tillage
Okra is more successful in mellow, well-drained and loosened soils. Tillage involves a number of operations:
– Debris removal and weeding
This consists in removing plant material (trees, shrubs, weeds). Care must be taken during this operation to remove rhizomes and
runners which may grow back (e.g. Cyperaceae). This can be done manually. However, if the field is covered only by weeds, chemicallyweeding prior to sowing can be implemented. An active ingredient such as Paraquat (2 to 3 litres/ ha) is effective against grassy weedsand annual dicotyledons.
– Stump removal
This operation consists in clearing the soil in depth to extract tree and shrub stumps that are damaging to tools and could interfere with
the development of the okra root systems. A winch can be used to remove large stumps.
Prior irrigation
The purpose of prior irrigation of the plot is to facilitate subsequent tillage operations. It consists in generously irrigating the plot (manualor mechanical sprinkling) by applying some 20 mm of water (20 litres or 2 watering cans/ m2).
– Application of organic material
The base dressing can be either of animal origin (horn meal and meal from other parts of animal carcasses, fish residues, poultry,
sheep, goat or cattle dung) or of plant origin (green fertiliser, ground-nut shells and dust, cacao pods, etc.). The best organic manure,
however, is compost, i.e., a mixture of various fermented and well-decomposed organic materials. The manure should be evenly spread over the field at a dose of between 40 and 100 tonnes/ha (i.e., 4 to 10 kg/m2).
– Ploughing and incorporation of organic material
Okra plant develops well on loosened, aerated soil. It is therefore important to plough through a depth of at least 20 cm to allow the
plant to develop properly. Either a tractor or a draft animal may pull the plough. Incorporation of the organic material, on the other hand,
can be done locally in the seed spots without mixing it with the soil. This has the additional benefit of restricting root-gall nematode
infestation.
– Application of base mineral dressing and harrowing Depending on the soil, the base mineral dressing can be applied at a dose of 250 to 400 kg/ha (in medium fertile soil), or 750 to 900 kg/ha (poor soil) of 10 – 20 – 20 fertiliser. The mineral dressing should be evenly applied directly on the soil surface. Harrowing consists in breaking down the clumps that subsist after ploughing and optimising soil aeration by loosening it. A rake can be used for small surface
areas, while on large surface areas in the case of mechanised farming, a harrow or a semi-manual walking tractor is used.
– Preparing seeding in seed spots
Okra seeds should be directly drilled. To abide by seed density requirements and align plants so as to facilitate upkeep while the plant
is growing, plots should be staked out along a 40 x 60 cm grid, which makes for a density of 41,750 plants per hectare (single row), or
25 x 50 x 80 cm, i.e., a density of 61,500 plants per hectare (double row). Seed spots should be 10 x 10 x 15 cm so they can contain
from 1 to 2.5 kg of mature, well-decomposed organic manure when dressings are applied locally. The soil at the bottom of the seed
spot should be loosened to encourage growth of the taproot system. Seed spots can be directly fertilised rather than applying organic
or mineral fertiliser prior to digging out the seed spots. If this option is chosen, 1 to 2.5 kg of organic manure per seed spot should be
applied, or 18-21 g. of base mineral fertiliser in poor soils and 5-10 g. per seed spot in medium soils.
• Seeding
8 to 10 kg of seeds are needed to seed one hectare of okra .
The germination capacity of seed batches should be laboratory tested using soaked filter paper on 3sub-batches of 100 randomly selected seeds each. This test is performed to improve chances of high emergence rates in the field by determining the seeds’ germination percentage before using them.
Soaking seeds in water 24 hours prior to seeding fosters germination.
3 seeds should be placed in a triangular fashion in each seed spot 1,5 to 2 cm below the soil line, and then covered with earth and slightly pressed down.
The planting densities that ensure adequate aeration of the field and development of the plants are in region of 41,750 plants/ha
(single row, 40 cm spacing within the row and 60 cm between rows), or 61,500 plants/ha (double rows, 25 cm spacing within the role, 50 cmbetween two adjacent single rows, and 80 cm between two adjacent double rows).
Or spacing varies: 45 x 45 cm, 50 x 30 cm or 60 x 15 cm between the rows and within the rows, respectively.
The seed spots should be lightly watered after seeding. When good quality seeds are used and the right degree of moisture is maintained in the soil, seedlings generally emerge within 4 to 6 days after seeding .
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