Introduction to Cotton
Cotton, a plant that yields the most important of all natural textile fibers. There are thousands of uses for cotton. A large part of the world's textile production is cloth made of cotton or blends of cotton and synthetic fibers. Cotton cloth is durable, easily laundered, and relatively inexpensive. The plant's seed provides edible vegetable oil and protein feed. Cotton also provides important raw materials for the chemical industry.
Cotton is one of the most important crops grown in the United States. Millions of people are supported directly and indirectly by the farms that grow it, the manufacturing concerns that process it, and the domestic and international marketing activities that distribute cotton products.
The world's leading cotton-producing countries and the leading cotton-producing states are shown in graphs later in this article. Most of the cotton produced in the United States comes from the Cotton Belt, a region about 2,300 miles (3,700 km) long and 700 miles (1,100 km) wide. It includes parts of North Carolina, South Carolina, Georgia, Alabama, Tennessee, Mississippi, Missouri, Arkansas, Louisiana, Oklahoma, Texas, New Mexico, Arizona, and California.
The Cotton Plant
The most common type of cultivated cotton is a woody plant that branches like a small tree and grows two to five feet (60–150 cm) high. The leaves are three to six inches (7.5–15 cm) wide, with three-pointed lobes. Cotton flowers look something like yellowish-white hollyhocks. They gradually turn red and fall off after three days, leaving the young fruit—a pointed, green capsule known as a boll ()—attached to the plant. It contains the young seeds and the valuable fiber for which the plant is grown.
The boll takes six to eight weeks to mature. It then splits into sections, opens wide, and releases a fluffy mass of fiber. In wild cotton, this mass serves as "wings" for the seeds, carrying them away on the wind. A large cotton plant may have more than 75 bolls. Each boll contains 30 to 35 brown or black seeds about the size of small peas.
Cotton fiber consists of slender, one-celled hairs that grow on the seed. The fibers vary in length from less than one inch (2.5 cm) to more than two inches (5 cm). When referring to fiber length, the term staple is used (as in "long staple" and "short staple"), the longer staples being considered the most desirable. Each mature fiber is shaped somewhat like a twisted ribbon. It is this spiral form that makes it possible to spin cotton. The spiral allows the fibers to interlock and hold the shape of the thread. The long fibers removed from the seed by the process of ginning are called lint cotton. The short, fuzzy remains that cling to the seeds after ginning are called linters.
Types of Cotton
There are more than 30 types of cotton plants, ranging from small shrubs less than one foot (30 cm) tall to trees more than 10 feet (3 m) high. Some of the better-known types are described below.
Sea Island Cotton,
with a staple of 1 3/8 to 2 1/2 inches (3.5–6.4 cm), has the highest quality fiber but its susceptibility to insect attack makes commercial production impractical. It is named for the Sea Islands (off the coast of the southeastern United States), where it was grown until the boll weevil halted production in the 1920's.
Egyptian Cotton
has yellowish fibers that are only slightly shorter than those of Sea Island cotton—1 1/2 to 1 3/4 inches (3.8–4.4 cm) long. This cotton is used in making thread, raincoats, underwear, and hosiery. An American type of Egyptian cotton, called American pima, is grown in the southwestern Cotton Belt under irrigation.
Upland Cotton
is the main type grown in the United States. It is also grown all over the rest of the cotton-producing world. The fibers are white, 3/4 to 1 1/2 inches (1.9–3.8 cm) long. The plant is 2 1/2 to 4 feet (75–120 cm) tall. It is native to Mexico and Central America.
Asiatic Cotton
has fibers less than one inch (2.5 cm) long and rather coarse in texture. It is grown mostly in India, Iran, China, and Russia.
Other Cottons of commercial importance include Peruvian cotton, with fuzzy, almost wool-like fibers, and Brazilian cotton, a perennial cotton with long, silky fibers. Levant, Mexican, and Jamaica cottons are wild varieties that may have been the early relatives of some modern varieties. Colored cotton has been produced by some agricultural experimenters, but cloth woven from it tends to fade in strong sunlight.
Raising and Harvesting Cotton
Climate and Soil
Cotton is a warm-weather crop that grows in the region between 40° north and 30° south of the equator. It requires moderate rainfall—a minimum of six to seven inches (150–175 mm) during the growing season. While the bolls are ripening, the climate should be drier. Six frost-free months are required for cotton growing. In tropical countries, cotton is a perennial. It grows to the height of 10 feet (3 m) and can be harvested all year round. In the far-western United States, cotton is grown on irrigated land.
The plant grows best in a fertile soil that contains some sand or clay. (Such soil is often found in valleys or near rivers.) Commercial fertilizers are applied to the soil in many areas to improve plant growth and increase yields.
Soil Preparation and Planting
In areas where cotton is an annual, rather than a perennial, stalks of the previous year's crop are cut up and plowed under before planting. Then the fields may be further prepared with a disk harrow. A bedding machine, usually drawn by a tractor, prepares the seedbed, and planting is done by machine. One, two, or four rows are planted at a time. In the southernmost United States, cotton is planted in March. Farther north, it is planted as late as May.
Cultivation
In some areas seeds are planted in continuous bands that must be thinned out when the plants spring up. However, most of the crop is planted in such a way that thinning, or "chopping," is not required. The young plants are cultivated by machine to kill weeds. Chemicals are also used, to prevent the growth of weeds.
Insect Enemies and Diseases
Cotton is subject to the attacks of many kinds of insects. Among these are the boll weevil, bollworm, pink bollworm, cotton fleahopper, red spider (spider mite), cotton aphid, and cotton stainer. The plants are dusted with insecticides several times during the season to kill pests. Rigid quarantines are used to prevent spread of the pink bollworm.
The fungus and bacterial diseases of cotton include root rot, fusarium wilt, bacterial blight, root knot, and anthracnose. These diseases are prevented by crop rotation, by use of fertilizers, by treating soil and seed with chemicals, and by planting varieties of cotton that resist disease.
Cotton Harvesting
Cotton requires about 200 days to mature. In much of the Cotton Belt the bulls begin opening in August and September. Although most of the cotton is harvested by machine, some is still gathered by hand. The most common method of hand harvesting is for workers to pick the lint from the open bolls. Since the bolls do not all mature at the same time, the fields must be gone over two or three times by the pickers. Another method of hand picking, called snapping, is to take the entire boll from the plant. It is faster than the common picking method, but can be used only with special varieties of cotton, and special gins are required to process the cotton.
The use of mechanical harvesters in the United States increased greatly after the end of World War II. The spindle-type mechanical picker uses vertical drums with revolving spindles to engage and pull the cotton from the open bolls. Since it does little injury to plants or unopened bolls, picking may be repeated as the younger bolls open. One machine can do the work of 30 to 40 hand pickers.
The stripper is used for mechanical snapping. These machines pull the boll from the plant with rollers, steel fingers, brushes, or other devices. A stripper harvests as much cotton as 20 laborers can by hand snapping.
Ginning Cotton
Lint cotton is separated from the seeds by a machine called a gin. A large pipe sucks freshly picked cotton from trucks or wagons into a tower, where it is dried if necessary. The dried cotton is fed through a series of rollers and toothed wheels that remove trash. The cotton is then conveyed to the gin stand, which removes the lint from the seed.
A typical gin stand consists of a gang of fine-toothed circular saws mounted on a revolving shaft and stationary bars placed between the saw blades. The saw teeth take the seed cotton up to the bars. The lint sticks to the teeth and passes through the bars. The seeds, too large to pass through, are separated from the lint and fall onto a conveyor belt. The lint is removed from the saw teeth by revolving brushes or by air pressure. It is then taken by pipe to be cleaned further, if necessary, and baled.
In a roller gin, used for some long-fiber cottons (such as SeaIsland), the lint adheres to rollers and the seeds are separated from the lint by vibrating blades.
Ordinarily, lint cotton remains the property of the grower, while the seeds are purchased by the gin operator.
King Cotton