Sisal ( Agave sisalana).
Sisal - Agave sisalana
Sisal, with the botanical name Agave sisalana, is a species of flowering plant, belongs in the Asparagaceae family,
native to southern Mexico but widely cultivated and naturalized in many other countries. It yields a stiff fibre used in making rope and various other products. The term sisal may refer either to the plant's common name or the fibre, depending on the context. The sisal fibre is traditionally used for rope and twine, and has many other uses, including paper, cloth, footwear, hats, bags, carpets, geotextiles, and dartboards. It is also used as fibre reinforcements for composite fibre-glass, rubber and cement products.
The native origin of Agave sisalana is uncertain. Traditionally it was deemed to be a native of the Yucatán Peninsula, but there are no records of botanical collections from there. They were originally shipped from the Spanish colonial port of Sisal in Yucatán (thus the name). The Yucatán plantations now cultivate henequen (Agave fourcroydes).
Agave sisalana is an evergreen, succulent plant. The plant stalk grows to about 90 cm (3 feet) in height, with a diameter of approximately
40 cm (15 inches). The lance-shaped leaves, growing out from the stalk in a large
dense rosette, are fleshy and rigid, with gray to dark green colour. Each is 60–180 cm (2–6 feet) long and 10–18 cm (4–7 inches) across at the widest portion, terminating in a sharp spine. Young leaves may have a few minute teeth along their margins, but lose them as they mature.
Within four to eight years after planting, the mature plant sends up a central flower stalk reaching about 6 metres (20 feet) in height. Yellow flowers, about 6 cm (2.5 inches) long and with an unpleasant odour, form dense clusters at the ends of branches growing from the flower stalk. As the flowers begin to wither, buds growing in the upper angle between the stem and flower stalk develop into small plants, or bulbils, that fall to the ground and take root. Like other Agave species, the old plant dies when flowering is completed.
The sisal plant has a 7-10 year life-span and typically produces 200-250 commercially usable leaves. Each leaf contains an average of around 1000 fibres. The fibres account for only about 4% of the plant by weight. Sisal is considered a plant of the tropics and subtropics, since production benefits from temperatures above 25 degrees Celsius and sunshine.
Sisal was used by the Aztecs and the Mayans to make fabrics and paper. In the 19th century, sisal cultivation spread to Florida, the Caribbean islands, and Brazil (Paraiba and Bahia), as well as to countries in Africa, notably Tanzania and Kenya, and Asia. Sisal reportedly "came to Africa from Florida, through the mechanism of a remarkable German botanist, by the name of Hindorf."
In Cuba its cultivation was introduced in 1880, by Fernando Heydrich in Matanzas.
The first commercial plantings in Brazil were made in the late 1930s and the first sisal fibre exports from there were made in 1948. It was not until the 1960s that Brazilian production accelerated and the first of many spinning mills was established. Today Brazil is the major world producer of sisal. There are both positive and negative environmental impacts from sisal growing.
The plants grow best in moderately rich soil with good drainage and in warm moist climates. Young plants, propagated from bulbils or rhizomes (underground stems) of mature plants, are usually kept in nurseries for the first 12 to 18 months. At the beginning of the rainy season, the plants are transferred to the field. These methods offer no potential for genetic improvement. In vitro multiplication of selected genetic material using meristematic tissue culture (MST) offers considerable potential for the development of improved genetic material.
Sisal matures about three to five years after planting, depending upon the climate, yielding satisfactory fibre for seven or eight years thereafter and producing about 300 leaves throughout the productive period. Outer leaves are cut off close to the stalk as they reach their full length. The initial harvest is about 70 leaves; subsequent annual production averages about 25.
Sisal fibre is made from the leaves of the plant.
Fibre is extracted by a process known as decortication, where leaves are
crushed between rollers, beaten, and brushed away by a rotating wheel set with blunt knives, so that only fibres remain. The resulting pulp is scraped from the fibre, and the fibre is washed and then dried by mechanical or natural means. Alternatively, in East Africa, where production is typically on large estates, the leaves are transported to a central decortication plant, where water is used to wash away the waste parts of the leaf.
The fibre is then dried, brushed and baled for export. Proper drying is important as fibre quality depends largely on moisture content. Artificial drying has been found to result in generally better grades of fibre than sun drying, but is not always feasible in the less industrialised countries where sisal is produced. In the drier climate of north-east Brazil, sisal is mainly grown by smallholders and the fibre is extracted by teams using portable raspadors which do not use
water. Fibre is subsequently cleaned by brushing. Dry fibres are machine combed and sorted into various grades, largely on the basis of the previous in-field separation of leaves into size groups.
The lustrous fibre strands, usually creamy white, average 100 to 125 cm (40 to 50 inches) in length and are fairly coarse and inflexible. Sisal fibre is especially valued for cordage use because of its strength, durability, ability to stretch, affinity for certain dyestuffs, and resistance to deterioration in salt water. The fibre is very similar to that of the related henequen (Agave fourcroydes).
Sisal is a valuable forage for honey bees because of its long flowering period. It is particularly attractive to them during pollen shortage. The honey produced is however dark and has a strong and unpleasant flavour.
Because sisal is an agave, it can be fermented and distilled to make
mezcal. In India it may be an ingredient in some street snacks. Sisal is a folk remedy for dysentery, leprosy sores, and syphilis. The leaves contain hecogenin used in the partial synthesis of the drug cortisone.
Traditionally, sisal has been the leading material for agricultural twine (binder twine and baler twine) because of its strength, durability, ability to stretch, affinity for certain dyestuffs, and resistance to deterioration in saltwater. The importance of this traditional use is diminishing with competition from polypropylene and the development of other haymaking techniques, while new higher-valued sisal products have been developed.
Apart from ropes, twines, and general cordage, sisal is used in low-cost and specialty paper, dartboards, buffing cloth, filters, geotextiles, mattresses, carpets, handicrafts, wire rope cores, and macramé. Sisal has been utilized as an environmentally friendly strengthening agent to replace asbestos and fibreglass in composite materials in various uses including the automobile industry. The lower-grade fibre is processed by the paper industry because of its high content of cellulose and hemicelluloses. The medium-grade fibre is used in the cordage industry for making ropes, baler and binder twine. Ropes and twines are widely employed for marine, agricultural, and general industrial use. The higher-grade fibre after treatment is converted into yarns and used by the carpet industry.
Other products developed from sisal fibre include spa products, cat scratching posts, lumbar support belts, rugs, slippers, cloths, and disc
buffers, fishing-nets, hammocks, door-curtains, floor-covers, bags etc..
Despite the yarn durability sisal is known for, slight matting of sisal carpeting may occur in high-traffic
areas. Sisal carpet does not build up static nor does it trap dust, so vacuuming is the only maintenance required. Depending on climatic conditions, sisal will absorb air humidity or release it, causing expansion or contraction. Sisal is not recommended for areas that receive wet spills or rain or snow. Sisal is used by itself in carpets or in blends with wool and acrylic for a softer hand.