Cotton is a cash crop produced in many countries. There is much history, as
well as many myths and legends associated with the crop. The first written
reference to cotton was in a Hindoo RigVeda hymn, written fifteen centuries
before Christ. The hymn mentions "threads in the loom", proving that cotton was
then already used in weaving. Further references include the "sacrificial thread
of the Brahman must be made of cotton", "there are trees which grow wild there
(India), the fruit of which is a wool exceeding in beauty and goodness that of
sheep"; "it was in form like a lamb, and from its navel grew a stem or root by
which this Zoophyte, or plant-animal, was fixed, attached like a gourd to the
Cotton is a member of the Malvaceae family and its species are distributed
mostly in the tropics and warm regions of the world. Some of the members of the
Gossypium genus are fibreless. The plants vary from shrubs to trees, can be
annuals or perennials. The leaf blades are usually palmately lobed with three to
nine lobes, with a longer or shorter petiole. The large flower has white, cream
or pale yellow petals which become pink to reddish after 12 - 30 hours. The
flower may have an eyespot deep within the calyx.
Cotton was first introduced into China from India as an ornamental and only
later, in about 1300AD, the crop came into general use. Japan has, however,
always been a consumer of cotton. Most varieties originally grown in Asia were
derived from Gossypium herbaceum. Other major sources of cotton varieties are
the Sea Island and Upland cottons that originate from the Americas. Naturally
occurring wild cotton types in Africa are found mostly in Sudan, but these could
have been brought to the continent by Arab traders. Interestingly, the clothing
and fabrics found in the ancient tombs of Egypt were always flax fibre and never
from cotton. Today, Egyptian cotton is very popular in certain specific
production areas and systems. The American types are more adaptable and planted
in more production areas.
The harvesting and subsequent handling of the crop entails the fibers being
separated from the seed in the mills in a process called "ginning". The fiber is
sold in "bales" and subsequently "spun" and "woven" to produce material for
garments or "yarns". The usefulness of cotton fiber depends on the quality,
which is determined by the colour, grade, staple length, fiber strength and lint
percentage. To determine fiber characteristics, a grader is used to produce a
cotton "butterfly" by easing the fibers away from the seed. However, different
levels of sophisticated machinery have been developed and currently the HVI-Lab
System has been widely introduced (Spinlab). It enables an
unbiased/non-subjective evaluation of quality.
Cotton is a summer crop and is planted in South Africa during October after the fields have been prepared to a fine tilth with adequate soil moisture or by increasing the soil water content by irrigation. The seed is introduced into the soil at a depth of between 25 - 40 mm. Under optimal conditions of soil-moisture, the seedling will emerge within 7 days. Thinning should take place at about 3 weeks after germination to adjust the plant population to 35 000 plants/ha for dry land (rain-fed) conditions or 80 000 plants/ha where irrigated farming is practiced. The plant will commence flowering at 70 days after planting, peak at 105 days and the peak flowering stage will be finished 130 days after sowing. The fiber in the pollinated flower now has to mature under favourable conditions of sufficient moisture, adequate nutrients and enough solar energy. The fiber attains its maximum length at 30 days after pollination and subsequently increases in strength due to the precipitation of cellulose on the inside of the fiber wall. When the maturation of the fiber in the bolls has terminated the stresses in the boll are so large that the burs are forced open and the characteristic white cotton bolls change the fields to a "winter wonderland" at the end of summer. The fiber then dries very rapidly. Harvesting by hand can commence, but for mechanical / machine harvesting the farmer should wait until at least 60% of the bolls have burst before harvesting the first picking. A second picking can be postponed to autumn since the last bolls take longer to open because the physiological requirements to force bursting are reached much later.
The harvested seed cotton is then either packed in bales of 150 - 200 kg or collected in mass bins and transported to the ginnery where the farmer sells his crop to the ginner. The price that is obtained is dependant on the grade awarded to the seed cotton. The grading is determined by the colour of the fiber, the amount of staining that may have occurred due to rain splashing soil onto the fiber or insect and fungal staining, as well as the amount of foreign debris in the harvested crop.
The ginner separates the fiber from the seed and cleans it by removing any foreign matter that is present. The cotton is then sold to the spinners while the "fuzzy seed" can be sold to industry.
Cotton fibre is put to a multitude of uses such as yarn, woven cloth or as
filling material in many forms. To be put to these uses the spinner has to blend
the fiber and comb it. Through an elaborate process of thinning and spinning the
fibers that are between 27 and 33 mm long are spun to produce the typical
endless yarns. The short fine fibers from the fuzzy seed coat are removed and
sold as the finest form of natural cellulose for the manufacture of explosives.
The seed is crushed to extract the oil and separate the husks from the pulp.
Husks are used for the production of artificial rubber, while the remaining
pulp, which has a high nutritional value, is sold to livestock farmers as cotton
Life without the fruits of the cotton plant would be less comfortable.
Therefore it is important that effort should always be made to ensure that this
major natural fiber is produced at an affordable input cost for the farmer with
a realistic financial return.