Fibre Crops (Definition And Examples)



Although the introduction of synthetic fibres has had a significant effect on the demand for natural fibres, there is still a good market for some of these crops and their cultivation is being continued in many parts of West Africa on an appreciable scale. In order to meet local demands for coarse fibres which are  used in the making of produce bags, crops such as jute appear to be ones which could become more widely grown, the processing operations also involve an appreciable amount of hand labour rather than the use of expensive equipment.

Fibre crops which are grown in West Africa such as: cotton, kapok, jute, rama and

Of the two main species of cotton grown in West Africa, Gossypium hirsutum, which is also known as upland cotton is most widely cultivated. 

This species includes the American types or cultivars often referred to as Allen cotton which are relatively short stemmed annual plants reaching about 1.3 m in height. These have pale yellow flowers and the mass of fibres and seeds which are produced after flowering, referred to as the cotton boll, are fairly large in comparison to the bolls produced  by the other species, Gossypium vitifolium, often referred to as Ishan cotton. These are taller plants, with deep yellow flowers,smaller bolls and produce a shorter length of fibre or lint. 

From work carried out by Rescarch Stations over many years the most suitable cultivars for growing in many areas have been identified and new hybrids have been either produced or introduced from other tropical countries.
Some of these are resistant to important diseases of cotton.
Cotton grows well on deep loam or clay loam soils which have a good content of organic material and is sensitive to both temperature and rainfall conditions.

The light intensity during the actively growing period is important and seeds are sown during the rains so that the crop will mature and the bolls ripen during the dry season. Excessive soil water is harmful to root development and plants are grown on ridges or mounds in high rainfall areas. Seeds are sown either on flat land, mounds or ridges and the seedlings thinned to leave either one or two vigorous  seedlings per stand. Cotton is a crop which is often interplanted with maize and yams. Weed control is necessary until the plants are well developed and later hoeing will reduce soil moisture loss, Many diseases and pests attack cotton and some can be prevented and partially controlled by treating the seeds with seed dressings, crop rotation, removal and burning of infected plants and using resistant cultivars, Many of the insect pests can be controlled by spraying with insecticides.

The crop is normally harvested by hand, although cotton harvesting machinery is used in some countries for large scale production. Cotton for export is usually ginned, this is the separation of the fibres or lint from the seeds. Seeds are also exported, since they contain a high percentage of edible oil which is used in the manufacture of margarine, salad oils and soaps. The residue from the oil extraction is used as a cattle food,

The silk cotton tree is common in West Africa and is successfully grown as a plantation crop in some areas.
Much of the kapok fibre which is exported is harvested from trees growing in a natural state. 

The tree grows well at elevations of less than 500 m and is very tolerant to soil conditions. For maximum growth and production, plants require a fairly long wet period which promotes vegetative growth, followed by a dry period for flowering and fruiting. Mature trees may reach 30 m in height, with trunks which taper towards the growing point, and may be productive for up to 60 years. The pods are harvested by climbing the tree, they are then broken open by hand and the seeds extracted by beating the dried fibres with sticks. 
The trees are rarely liable to damage by insects or diseases.

Two species of Corchorus, C. capsularis and C. olitorius are used for the production of jute in West Africa although some selections of C. olitorius are also used as a vegetable.

The fibres, which are obtained by soaking the stems in water, or retting, and then peeling, separating and drying them, are used in the manufacture of produce bags. Jute is not widely grown in West Africa but its production is likely to increase in relation to the demand for produce storing, handling and transport containers and the rise in costs of imported materials for bag production. Several cultivars have now been selected which are suitable for growing in specific areas. A moderate and heavy rainfall, which is regular and distributed over a fairly long wet season, is an advantage since jute is a crop of the lowlands and also requires fairly high and stable temperatures. 

Fertile soils of a medium clay loam content are required for high yields. Seeds are sown either broadcast or in rows and are thinned when about 10-15 cm in height. 
Corchorus capsularis selections often grow to a height of 3-4 m but some cultivars may grow taller than this.

The main objective is to produce tall unbranched plants with a high fibre content; this can be achieved by using a fairly close spacing. The crop should be
weeded until well established, and when mature, the stems are cut a few centimetres above ground level.

They are tied in bundles before being placed in the retting tanks or in a stream where running water is an advantage to the retting process. During this period, bacteria and other micro organisms assist in breaking down the non fibrous stem contents. After about 10 days, the stems are removed from the water and the fibrous outer layers are separated from the woody central part. They are then dried and decorticated. This process results in macerating and breaking apart the fibres so that they can be used for weaving into produce bags and other containers.

Rama, Congo jute 

This plant yields a fibre which is similar in properties to jute and is often used with jute in the manufacture of bags and sacks. It is a perennial, low growing hairy shrub but some selected cultivars, when planted closely together, develop a tall straight stem.

As with most woody fibre crops, Congo jute requires a deep fertile soil, with a fairly long wet season and grows best in lowland areas which have high stable temperatures.
Seeds are either broadcast or sown in rows and thinned, the main objective is to ensure close spacing so that the plants develop straight stems. The harvesting, retting  and decorticated  operations are similar to those used for jute.

This is also a minor fibre crop in West Africa at the present time, but is likely to increase in importance; the fibres are used in a similar manner to those of jute but are more coarse, less flexible and more liable to rotting. Well drained, sandy loams which have a good content of organic material are suitable for this crop which requires a wet season of about 4-5 months.

Seeds may be sown on ridges or in rows, close spacing between plants in the row is required for the production of tall, straight stems. Weeds should be controlled in the early stages and the plants harvested when the first flowers form, at which time the fibres are well developed and can be easily separated. 
The stems are cut just above ground level, tied in bundles and retted in moving water, as for jute. The bark is then separated from the woody stem portion, beaten or decorticated to separate the fibres and dried in the Sun.


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