NOTICE: Hard copies of the Australian New Crops Newsletter are available from the publisher, Dr Rob Fletcher. Details of availability are included in theAdvice on Publications Available.
By Ian Wood
IM Wood and Associates
258 Bielby Road
Kenmore Hills, Queensland 4069
Telephone: 07 3378 5911
Facsimile: 07 3378 4072
[Ian Wood has kindly agreed to prepare a series of short articles on fibre crops which will be regularly published in the Australian New Crops Newsletter.
His publication, 'Fibre Crops - New opportunities for Australian agriculture' is highly recommended. It is published by the Queensland Department of Primary Industries and is available from:
Queensland Department of Primary Industries
GPO Box 46
Brisbane 4001 Queensland
Telephone: 1800 816 541 (from within Australia)
Price: AUD25 + postage]
Ramie (Boehmeria nivea (L.) Gaud., Boehmeria nivea var tenacissima), commonly known as Chinese grass, white ramie, green ramie and rhea is one of the group referred to as the bast fibre crops.
However, it differs from the other bast fibre crops in several important characteristics.
The first is that ramie is a hardy perennial which under suitable conditions can be harvested up to six times a year.
As well, the useful crop life ranges from 6 to 20 years.
The second difference is that the bark contains gums and pectins which necessitate a chemical treatment to recover the bast fibres.
Ramie is one of the oldest textile fibres.
It was used in mummy cloths in Egypt during the period 5000-3300 BC and has been grown in China for many centuries.
The main producer counties are reported to be China, Brazil, Philippines, India, South Korea and Thailand but the available statistics are not reliable. This is because production statistics for ramie are included in the Fibre Crops NES (Not Elsewhere Specified) in the official FAO Production Statistics (FAO 1995).
Brazil began production in the late 1930s with production peaking in 1971 with about 30,000 t. Since then, production has steadily declined as a result of competition with alternative crops, such as soybeans and the importation of synthetic fibres.
Production in the Philippines began in the early 1950s, peaking in the mid 1960s with 5,500 t. Since then, production has declined steadily.
The main importing countries are Japan, Germany, France and the United Kingdom. Only a small proportion of production enters international trade as most is used in the country of production.
Ramie is a member of the Urticaceae or nettle family and is a hardy perennial which produces a large number of unbranched stems from underground rhizomes.
The true ramie or 'China grass' is also known as 'white ramie' and is the Chinese cultivated plant. It has large heart shaped, crenate leaves covered on the underside with white hairs that give it a silvery appearance.
A second type, Boehmeria nivea var tenacissima, is known as 'green ramie' or 'rhea' and is believed to have originated in the Malay Peninsular. This type has smaller leaves which are green on the underside and it appears to be better suited to tropical conditions.
The stems of ramie grow to a height of 1 to 2.5 m. The crop is generally propagated vegetatively, using rhizome or stem cuttings. Production begins to decline once roots become overcrowded.
Roots suffering overcrowding require thinning out or the area must be replanted.
The most suitable climate for ramie is one which is warm and humid with an annual rainfall (or irrigation) of at least 1000 mm, evenly spread over the year. The crop is tolerant of a range of soil types but is reported to be sensitive to waterlogging.
Well established plants can tolerate moderate drought and frost but grow better where these are absent. The crop prefers slightly acid soil conditions with pH in the range of 5.5 to 6.5.
As productivity is high, ramie can rapidly deplete the soil of nutrients so it is therefore important to either return the plant residues to the soil or add organic or inorganic fertilisers.
Ramie is normally harvested two to three times per year but under good growing conditions can be harvested up to six times per year. The timing of the harvest of a particular stem is important as fibre yields are reduced if it is immature. As well, there are difficulties in removing the fibre if the stem is over mature.
Harvesting is done just before or soon after the onset of flowering, since there is a decline in plant growth at this stage and maximum fibre content is achieved.
Stems are harvested by cutting just above the lateral roots or the stem can be bent, to enable the core to be broken and the cortex can be stripped from the plant in situ. Mechanical harvesters have been developed but are not used commercially.
After harvesting, stems are decorticated while the plants are fresh as the bark gets harder to remove as the plant dries out. The bark ribbons are dried as quickly as possible to prevent attack by bacteria or fungi.
Crop and fibre yields
The dry weight of harvested stem from both tropical and temperate crops ranges from about 3.4 to 4.5 t/ha/year; a 4.5 tonne crop yields about 1,600 kg/ha/year of dry undegummed fibre.
The weight loss during degumming can be up to 25% giving a yield of degummed fibre of about 1,200 kg/ha/year.
Extraction of fibre
Extraction of the fibre occurs in three stages.
Firstly, the cortex or bark is removed, either by hand or machine, in a process called decortication.
The second stage involves scraping the cortex to remove most of the outer bark, the parenchyma in the bast layer and some of the gums and pectins.
The third stage involves washing, drying and degumming of the residual cortex material to extract the spinnable fibre.
Details of the degumming processes tend to be regarded as commercial-in-confidence information.
Most of the processes involve a treatment with caustic soda to dissolve the residual pectins and gums.
Ramie fibre is one of the premium vegetable fibres.
The ultimate fibres are exceptionally long and are claimed to be the longest of vegetable origin, with one report claiming the fibres range up to 580 mm, averaging about 125 mm.
Another report describes the ultimate fibre as ranging between 48 and 290 mm in length.
One US study reported the range of bark fibre length as 5 to 36 mm and the fibre width as 41.8 microns.
Ramie fibre is very durable, is pure white in colour and has a silky lustre.
It is reported to have a tensile strength eight times that of cotton and seven times greater than silk.
However, other reports claim that the tensile strengths of cotton, flax, hemp and ramie are similar.
These discrepancies can be partly attributed to the effects of source of supply, method of processing, the test conditions, temperature and humidity, on the fibre strength.
Uses of ramie fibre
Ramie fibre is used in fine linen and other clothing fabrics, upholstery, canvas, filter cloths, sewing threads, gas mantles, fishing nets and marine packings.
When used in admixture with wool, shrinkage is reported to be greatly reduced when compared with pure wool.
Short fibres from processing wastes are used for the production of high quality papers, such as bank notes and cigarette papers.
Pulping trials conducted in the USA rated ramie as among the best of the potential pulp sources.
Potential production areas in Australia
Successful trial plantings of ramie have been conducted at Rockhampton, Yeppoon and Emerald in Central Queensland.
Ramie's role in farming systems
The following characteristics of the ramie crop would influence its suitability in Australian farming systems:
Commercial prospects for ramie in Australia
It is difficult to obtain accurate information on the level of current imports of ramie fibre and fabric into Australia and the value of those imports.
Ramie fibre is acknowledged as a high quality fibre but its production is labour intensive and unlikely to be economic under current Australian conditions.
The need for chemical treatment to extract the fibre has also been seen as a serious disadvantage.
However, experience with many other new crops introduced into Australia has shown that all facets of production and processing can now be mechanised and this could make Australian-grown fibre competitive with production from traditional growing areas.
The potential for production in Australia and the likely demand for this high-quality fibre would appear to warrant a more detailed assessment of the opportunities.
This assessment would need to establish the level and value of current imports of fibre and fabric and seek to establish likely future demand.
It would also be important to identify the potential growing areas and assess the likely profitability of ramie production relative to current crops.
Such assessments would need to assess the prospects and costs of mechanising all facets of production and processing.
As cotton is currently the major plant fibre produced in Australia it would be important to compare the relative costs and returns from cotton and ramie.
If ramie did become an established crop in Australia any waste fibres from the textile industry could be used to produce high-quality specialty paper.
Any claims made by authors in the Australian New Crops Newsletter are presented by the Editors in good faith. Readers would be wise to critically examine the circumstances associated with any claims to determine the applicability of such claims to their specific set of circumstances. This material can be reproduced, with the provision that the source and the author (or editors, if applicable) are acknowledged and the use is for information or educational purposes. Contact with the original author is probably wise since the material may require updating or amendment if used in other publications. Material sourced from the Australian New Crops Newsletter cannot be used out of context or for commercial purposes not related to its original purpose in the newsletter
Contact: Dr Rob Fletcher, School of Land and Food, The University of Queensland Gatton College, 4345; Telephone: 07 5460 1311 or 07 5460 1301; Facsimile: 07 5460 1112; International facsimile: 61 7 5460 1112; Email:firstname.lastname@example.org
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originally created by:GK; latest update 6 June 1999 by: RF