a natural vegetable fiber of great economic importance as a raw material for cloth and many other products
Cotton's strength, absorbency, and capacity to be washed and dyed also make it adaptable to a considerable variety of textile products. In fact, cotton can be made into more kinds of products -- from diapers to explosives -- than any other fiber.
Eli Whitney invented the cotton gin in 1793. This machine made it possible to remove the cotton seeds from the fibers more cheaply. With it, one person could do the work once done by 50 persons picking out seeds by hand. Before the American Civil War, cotton ranked as the only important crop of the South. Cotton still ranks as a major source of income for Southern farmers, but they now also raise a variety of other crops.
The Cotton Plant
Cotton is produced by small trees and shrubs of the genus Gossypium, of the family Malvaceae, which also includes hibiscus, okra, and the swamp mallow. The plant grows upright and has branches spreading in all directions. It has broad leaves with three to five lobes, and a taproot that may grow as deep as 4 feet into the ground.
White flowers blossom from the squares (buds) approximately five to seven weeks after planting. The flowers open in midmorning and begin to wither the next day. They turn pink, blue, and finally purple as they dry and fall off the plant. The flowers must be pollinated during the few hours they remain open. Cotton flowers usually pollinate themselves.
At first, only one or two flowers open each day. The first flowers bloom low on the plant, near the main stem. As the plant become larger, several flowers open daily. These flowers open higher on the plant and farther out on the branches. Flowering starts in summer and may last until the autumn frosts.
The boll, which contains the cotton fibers, begins to form while the flower withers. A boll matures in 45 to 60 days, during which time it grows to about the size of a golf ball. At full size, it is green and almost round, with a pointed tip. At this stage, the boll cracks in four or five straight lines from the tip. Then it splits open, showing four or five locks (groups of 8 to 10 seeds with fibers attached). The open dried boll, which holds the fluffed-out cotton, is called the bur. An average boll will contain nearly 500,000 fibers of cotton and each plant may bear up to 100 bolls.
Types of Cotton
There are several species of wild cotton in the world. They are found in Australia, Africa, Arizona, Central America, Lower California, Brazil, Mexico and other tropical countries and islands. Because of problems related to their refinement, however, they are not economically feasible to use. Through genetic assistance and breeding, today's cottons have evolved from these wild sources and are more processing friendly.
Currently, there are five major types of cotton being grown commercially around the world: American upland, Egyptian, Sea-Island, Asiatic, and American Pima. The various kinds of cotton plants resemble each other in most ways, but they differ in such characteristics as color of flowers, character of fibers, and time of blooming. In addition, each main type has varieties with different characteristics. Some varieties grow best on irrigated land. Some have lint 1¾ inches long, and others have lint only ½ inch long. Some varieties have stronger fibers than others. Some are easier to harvest by machine than others.
Cotton farmers in temperate regions, where most cotton is grown, must plant their crops every year. But in the hot, moist tropics, cotton plants may bloom for several years. Some of these plants grow over 10 feet high.
The cotton fibers shown in the photo at left are from the following varieties of cotton plants: 1) Sea-Island; 2) Egyptian; 3) American Upland Long-Staple; 4) American Upland Short-Staple; and, 5) Asiatic.
American Upland Cotton (Gossypium hirsutum) is the most commonly planted type of cotton in the world, making up about 90 per cent of the world's cotton crop. The multibranched shrub-like plant may grow 1 to 7 feet tall, has creamy-white flowers, and produces white fibers up to 1¼ inches long. It can be made into many kinds of fabrics, and is used both for heavy canvas and for expensive shirts. It is grown as an annual.
Egyptian Cotton (G. barbadense) was developed from stocks that originated in South and Central America. Menoufi, the most widely used variety, has exceptionally strong fibers about 1½ inches long. It has lemon-colored flowers and long, silky, light-tan fibers. It is made into clothing, balloon cloth, typewriter ribbons, and other fine fabrics.
Sea-Island Cotton first grew on the islands off the coast of South Carolina, Georgia, and northern Florida. It is now grown primarily in the West Indies. One of the most valuable and costly kinds of cotton, it has silky fibers that are about 1¾ inches long that can be made into very high-quality textiles. The plant has brilliant yellow flowers and white lint. It is expensive to raise, however, because it grows slowly and has a low yield and small bolls. Technically, Sea-Island is closely related to Egyptian cotton, but growers consider it a separate kind of cotton because of its different fiber characteristics.
Asiatic Cotton (G. arboreum) is grown mainly in China, India, and Pakistan. It has short, coarse, harsh fibers, and low yields. It is used for blankets, padding, filters, and coarse cloth.
American Pima Cotton is a hybrid derived from Egyptian and American Upland cottons. It is the only variety of long-fiber cotton now grown in commercially significant quantities in the United States, where is is cultivated under irrigation in the Southwest.
Uses of Cotton
All parts of the cotton plant are useful. The most important part is the lint (fiber) used in making cotton textiles. Cottonseed provides oil and forms the base of many food products. The linters, or short fuzz on the seed, are used in making cushioning, paper, plastics, and other products. Farmers plow under the stalks and leaves as humus to improve soil structure.
Lint is used to make all kinds of clothing, from hats to shoes. Chemists have made cotton fireproof, waterproof, rotproof, shrinkproof, and wrinkle-resistant. Household goods made of cotton include rugs, towels, and bed sheets. Other cotton-fiber products include abrasives, adhesive tape, bookbindings, diapers, and wall coverings.
Oil is the most important product made from cottonseed. In some cotton-oil mills, machines crush the kernels of the seed and crush out the oil. Other mills roll out the kernel so that it looks like oatmeal then use chemicals to dissolve the oil out of the seed. Refined (purified) cottonseed oil forms the base for such products as margarine, salad oil, shortening, and a frozen desert called mellorine. The remains of the refining process are used in products such as soap, linoleum, and phonograph records. The meal that remains after the oil is removed from the cottonseed contains enough protein to make it valuable as food for farm animals. The hull is used for chemicals and as a mulching material.
Many industries use chemically treated linters as raw materials for such products as plastics, photographic film, paper, and sausage casings. Explosives manufacturers use linters in guncotton. Linter fibers are also used to stuff mattresses, cushions, and pads. Linters that have been bleached and sterilized are used as medical cotton.
Where Cotton Is Grown
Worldwide, nearly 5 million pounds of cotton were grown in 2005, with almost half of that production coming from China and the United States. Pakistan, Uzbekistan, Brazil, Turkey and Australia also produce significant cotton crops.
Approximately 18 million pounds of cotton were produced in the United States in 2005. Texas is the leading producer of cotton in the United States, accounting for almost 25 percent of total production.
[*one bale weighs 480 pounds]
|The Robinson Library > Agriculture > Plant Culture > Field Crops|
This page was last updated on 03/20/2014.