ABSTRACT
Historical background
Recent developments in fibre hemp cultivation
Fibre hemp: botanical characteristics relevant to industrial use
Fibre hemp processing
Retting: the initial post-agricultural production process
Enzymatic retting process
Green hemp processing
Hemp and the textile industry
Hemp seed, hemp oil and by-products
Regulatory aspects
The contribution of genetics
European Union regulations and hemp crop subsidies
Problems relating to production of high quality bast for the textile industry in the light of current European Union regulations
References
Bibliography
Author: G. MIGNONI
Creation Date: 1999/12/01
G. MIGNONI
Agronomist and Fibre Crop Consultant, Kenaf Eco-Fibers, Rome, Italy
After a continued decline in fibre hemp cultivation and industrial processing during the post-war period, a sudden upward trend is now being noted in the industrialized world, especially in Europe. This new interest in licit cannabis cultivation stems both from a growing consumer demand for natural fibres and from the so-called "set-aside" and diversification farming policy of the European Union resulting in an intense search for profitable new non-food crops. Mounting concern over such ecological issues as the gradual depletion of worldwide available natural fibre resources using wood also contributed to this development. While "green" textiles appear to constitute the most immediately lucrative market for hemp, paper production is likely to absorb the biggest volumesin the future. As a result, the trend in Europe quickly reversed, and both the number of European countries again authorizing licit cannabis cultivation and the total area harvested has increased over the last 10 years.
Also, new research work and funds are being invested in each major segment of this agro-industry to increase its competitiveness further, and to minimize the risk of misuse. To improve the biological base, plant breeding and selection work pursues two principal objectives:
(a) To adapt the plant to specific climatic and environmental conditions while improving per hectare fibre yields and quality for the two principal applications, textiles and paper production;
(b) To reduce and ultimately eliminate the plant's psychoactive chemical principle, tetrahydrocanabinol (THC), as part of a regulatory safeguard mechanism. This latter objective has grown out of an increasing concern over potential misuse of fibre hemp cultures by drug abusers and became an important constituent of a new regulatory system within the European Union as of the early 1980s.
The principal purpose of technology research is to develop and introduce more advanced and environmentally friendly technology for each processing step (e.g. retting, pulping) to make hemp fibre a more attractive and versatile raw material for an ever wider range of specific applications.
The above tendency is also complemented by efforts aimed at developing markets for more diverse industrial uses of other parts of the plant such as the seeds and of a range of crude products prepared from them.
Cannabis ( Cannabis sativa L .), or hemp, was one of the first--if not the first--non-food industrial plants to be used by man. While certainly native to Asia, its precise origin has not yet been identified. Current opinion, however, indicates an early diffusion over a vast area stretching from the Caspian Sea basin to the southern Himalayas then extending into China and western Siberia, where today, in the Altai valleys, it can still be found in its wild state [1].
Hemp was first domesticated by man in northern China some 5,000 or 6,000 years ago and archaeological finds confirm it was already being cultivated and presumably used as a textile fibre in 5000-4000 B.C. Other uses for hemp fibre were developed, for example, in paper-making. The world's oldest surviving example of paper, again discovered in China and produced in the first century B.C., was made entirely from hemp fibres. During the Western Han dynasty (A.D. 25-220), Cui Shi Han's Si Min Yue Ling gives ample details not only of hemp cultivation techniques but also of those to be adopted for quality control [2]. The earliest Chinese treatise on agriculture, Guy Shi Xian's Xia Xiao Zheng, written during the Northern Wei dynasty (A.D. 386-534), refers to hemp as one of the country's main crops [3].
Introduced into India long before the start of the Christian era, the plant was initially used for ritual or medical purposes and only later, around the first century A.D., as a textile fibre. A Sanskrit text dating from the seventh or sixth century B.C. refers to cannabis as a medication, bhang, a name also mentioned in the Atarva Veda (2000-1400 B.C.).
Ethno-botanists generally concur that hemp spread to Europe on the wave of Scythian migrations from the northern shores of the Black Sea and finds dating from the eighth century B.C. at Gordion in Turkey are evidence of this. It then spread westward and, above all thanks to the Etruscans [4], expanded throughout Italy in the sixth and fifth centuries B.C., where it ended up being synonymous with flax. The Greek historian Herodotus (484-408 B.C.) mentions hemp when speaking of Dario I's campaigns in Thrace (today Bulgaria), while four centuries later Pliny also refers to it, though only as a source of fibre for cords and hunting nets, not as a textile fibre.
In terms of textile plants and their use in the ancient world, hemp dominated in the East whereas flax was the major crop in Europe and North Africa. For instance, while hemp did spread to Egypt, there is no evidence that hemp cloth was ever used to bind mummies, even though traces of hemp cultivation have reportedly been found along the banks of the Nile. True expansion took place only in about the seventh century A.D., first to Syria and then to Egypt, as a narcotic plant, however. Caravans penetrating deep into Africa then introduced hemp throughout the continent, where it was used by various tribes in religious rituals, even to the point that the plant was sometimes considered sacred.
Hemp cultivation underwent rapid development during the fourteenth and fifteenth centuries, in particular in central Italy, owing probably to rising demand for ropes by Italian and foreign shipowners thanks to the fibre's extraordinary resistance to water and salt. But the use of hemp for textile purposes in Europe only really began in the sixteenth century. Piero de Crescenzi (c.1510) was the first to cite use of hemp bast for textile purposes in Italy, mentioning that it was "roughly like flax".
The New World saw the introduction of hemp cultivation during the sixteenth century, first in South and later in North America. Hemp was considered so important by the Spanish royalty that it imposed a mandatory crop quota throughout "New Spain", wherever climatic conditions permitted. In Chile hemp began to spread in 1545 in the Valparaiso area [5], around the town of Quillota to the north of Santiago.
Puritans brought hemp to North America in 1645 and it spread throughout Massachusetts, Connecticut, Virginia and then on to Kentucky in 1775. Between 1840 and 1860 demand for sailcloth and ropes by the United States Navy led to the height of its expansion and cultivation. Similarly in Canada, French and British colonial administrations expanded hemp cultivation between 1750 and 1850 during the golden age of sailing ships, and even created a strong flow of exports towards Europe.
With the beginning of the steamship era in the late nineteenth century, demand for hemp started to decline, in particular in Europe and North America. The industrial revolution brought more widespread affluence, which in turn meant that advances in processing technology concentrated on more refined textile fibres such as cotton or animal fibres such as wool.
Competition from alternative fibre sources further eroded the market for hemp textiles. Rayon, the first artificial fibre, was developed in France in 1884. Then in the 1900s synthetic fibres became a further competitor, contributing to the decline in hemp production. In the postwar period the world harvested area amounted to approximately 1 million hectares (table 1), with the production increasingly concentrated in Asia. Throughout that period hemp continued to find a market, although figures on worldwide production only start to become reliable from the time the Food and Agriculture Organization of the United Nations (FAO) was founded in 1945.
Table 1. Hemp: world harvested area, 1948-1997
(Average thousands of hectares per period)
| 1948-1952 | 1961-1965 | 1974-1976 | 1985-1988 | 1989-1991 | 1992-1994 | 1995-1997 a | |
| World | 1 085 | 633 | 562 | 385 | 198 | 145 | 130 |
| Asia | 203 | 221 | 339 | 197 | 114 | 105 | 103 |
Source: Food and Agriculture Organization of the United Nations.
a
Estimate.
In the last 50 years the world harvested area for hemp has decreased by a factor of eight (see table 1), although yields during the same period have almost doubled. The end result is that textile fibre production has only fallen by a factor of four. Figures for 1996 show that 78 per cent of the world harvested area was concentrated in Asia, while Europe and South America contributed the remainder. Production percentages reflected similar proportions, whereas Europe showed slightly higher yields. It should be mentioned that while data has been derived from FAO sources, European Union (EU) data tend to be more accurate. In fact, subsidies currently awarded to European hemp producers have led to better administrative oversight of the areas concerned.
Subsidies have certainly given new impetus to hemp textile crop production within the EU area, but mounting awareness regarding ecological issues and public opinion have also played a significant role, as shown by the stricter regulations now imposed on industry. These factors have led to substantial developments in terms of new technologies to produce ecologically safe and recyclable industrial products. The overall result has been an abrupt reversal of the negative trend previously seen for the hemp harvested area within EU (see table 2).
Table 2. Hemp: European Union harvested area, 1980-1997
(Average hectares per period)
| 1980-1982 | 1983-1985 | 1986-1988 | 1989-1991 | 1992-1994 | 1995-1997 | |
| Total | 5 840 | 5 441 | 4 986 | 3 822 | 6 652 | 15 233 |
Source: Fédération nationale des producteurs de chanvre, Le Mans, France.
From 1982 to 1985, France was the only country to continue the tradition of industrial hemp cultivation in western Europe. The following years saw first a progressive reduction in harvested area--in spite of the fact that Spain introduced hemp in 1986--but then, from 1990 onwards, there was a rapid increase from 4,191 to a total of 22,246 hectares in 1997. Seven European countries participated in the EU 1997 hemp harvest (Austria, France, Germany, Greece, Netherlands, Spain and the United Kingdom of Great Britain and Northern Ireland), with France alone still representing almost 50 per cent of the total harvested area. As for 1998, the participation of Italy has already been announced and it is likely that Belgium, Ireland and Portugal will also join the programme.
It should be mentioned that while the term "fibre cannabis" or "hemp" is used throughout the present paper, uses range beyond that of yarn production. Today, in fact, the major growth potential for hemp as a plant species is as a replaceable cellulose raw material for use in many industrial sectors. Apart from the paper industry, it is now also used in construction work in the form of fibreboard insulation material and in the form of pressed panels in the motor industry, while the oil finds uses in the paint, detergent and lubricant sectors and in cosmetics, as well as health food [6], and the seed cake as an animal feed.
Hemp-- Cannabis sativa L.--is an annual plant species belonging to the order Urticales, family Cannabinaceae and genus Cannabis. It is a diploid with the chromosome number 2n=20 and older textile fibre varieties, wild plants and narcotic populations are typically dioecious, heterogamous. Given that the male and the female inflorescences are carried by different plants, these are commonly referred to as "male plants" and "female plants". However, examples of monoecious plants can also be found within any given population--namely, single plants bearing both male and female inflorescence--and, furthermore, hermaphrodite inflorescence on mono-sexual plants [1].
Among the 14 varieties registered in EU for cultivation and subsidy, 11 are monoecious varieties selected by French researchers, whereas the remaining 3 Italian varieties are dioecious. From the agronomical standpoint, what differentiates the monoecious and dioecious varieties is the time at which their stems reach maturity. All plants in monoecious varieties show the same rate of development. On the contrary, in dioecious varieties the male plant flowers before the female. This factor leads to particularly important differences when hemp is to be used for textile purposes.
For reasons that will be discussed later, fibre qualities peculiar to either dioecious or monoecious varieties determine the use of hemp as a raw material for different industrial purposes. Dioecious varieties produce textile fibres, while monoecious varieties are preferred by the pulp and paper industry. There is no significant difference in use of the hurd--the woody portion of the stem--based on the two varieties.
Hemp produces three raw material components significant for the processing industry: bast and hurd, for various industries using the fibre and/or cellulose component, and seed, for extractive industries, fisheries, animal foodstuffs and other uses.
Bast is that part of the cortex external to cambium made up of primary fibres and secondary free fascia. While primary fibres are found throughout all stem internodes, secondary ones are sometimes also present but in a more internal position compared with the former. There are between 2 and 20 primary and up to 40 secondary fibres, both of which are joined to form strings [1].
Retting is the term used for processes that separate plant fibres, rendering them suitable for further processing as a raw material in the textile and paper industry. Retting in water can take place either through the action of amylobacteria, a natural constituent of the hemp stem's microflora, or by employing microbic retting agents, for instance, Bacillus felsineus. Above all they attack pectic substances during the fermentation process whereas the main products of decomposition are hydrogen, carbon dioxide, organic acids such as acetic, butyric and small amounts of valerianic and lactic acid. Other anaerobic bacilli found during retting are Granulobacter pectinovorum and Granulobacter aerocephalum.
This retting process takes place with the plants completely immersed in water. As the plants naturally tend to float, stem bundles or "rafts" are weighted down so that they are completely covered by retting water. Soluble bonds are attacked during the initial stages of fermentation and then insoluble gummy-resinous components (pectin) are biochemically transformed into soluble compounds. The process lasts 7-9 days. It also produces malodorous fermentation gases, which, together with the retting waters, constitute the polluting products that society today insists must be reduced and biodegraded. For this reason modern techniques tend to employ enzymes to achieve a bio-ecological form of retting.
While the traditional retting process still continues to be used in many countries, in particular developing nations, application of the process is impractical in industrialized countries as a result of environmental laws now in force. Apart from pollution and attendant social and health problems associated with the process, it is clear that it would not be easy to find the necessary manpower for such an unpleasant job. It is therefore realistic to assume that the relaunch of hemp as a crop in industrialized countries--especially in Europe--will be closely linked to the adoption of enzyme-type or equivalent advanced retting processes.
China--today the major supplier of retted hemp to industrialized countries--is substituting traditional processes by enzyme-type retting, thanks to techniques developed by local technicians. These are already adopted on an industrial scale and would seem to offer satisfactory qualitative results, given the level of exports China has achieved.
France, the major EU hemp producer, has deposited a patent request for a retting process developed jointly by J. S. Akkawi and the Comité économique agricole de la production de chanvre [8]. As this process is an integral part of a textile plant, all operations, from raw material harvesting up to production of dry retted material suitable for textile industry use, can be optimized and guaranteed.
The enzymatic process solubilizes pectic substances that bond fibres in stems. In nature solubilization occurs when bacteria present on the stems secrete a group of enzymes that catabolize starch, hydrolyzing it to maltose. In the French process, a mixture of enzymes developed specifically for the purpose is added to the raw material and then pectic substances are solubilized by treating it in an autoclave at 50 C for 18 hours. The end result is a homogeneous product with constant qualitative properties as required by end-users.
As mentioned previously, one process used to obtain hemp textile fibre is by retting the stems after harvesting. There is, however, an alternative process--known as scutching--that can be employed to transform green hemp stems directly into fibres [5]. Considering yield, one hectare of hemp provides 8-14 tons of retted material, whereas some 24 tons of green scutched product can be obtained, although the latter process is technically much more complex. While scutching clearly offers economic benefits in terms of yield, the two processes also lead to fibres with very different properties, above all in terms of spinning.
The excessive length of fibres obtained by scutching may be one of the causes of its poor spinning properties. A further problem is the separation of fibre fascia. In the absence of retting, pectic and resinous substances remain and bind the primary fibres more tenaciously. Chemical or mechanical processes can be used to overcome these problems.
Figure I shows the fibre yield for hemp after removal of other botanical parts.
The Qi Min Yao Shu ("Essential arts for the people"), the first Chinese scientific treatise, written in the sixth century A.D., states:
"If we pull out the male hemp before it scatters pollen, the female plant cannot make seed. Otherwise, the female plant's seed production will be influenced by the male plant's scattering pollen during this period of time. The fibre of the male plant is the best."
This quotation, apart from preceding any mention in Western sources by 1,000 years as regards the dioecious nature of the Cannabis species, also highlights the best moment to harvest it.
For any variety the timing of harvesting effectively determines the fibre's textile properties and quality, given equal retting processes. From the textile standpoint, bast obtained from monoecious varieties is lower in quality than that of dioecious varieties when both are harvested at the optimum time, that is, at the end of the flowering stage for male plants.
Studies have been conducted to evaluate the qualitative differences between bast produced by male and female dioecious varieties and monoecious varieties [9] (see table 3). These clearly demonstrated that bast from dioecious plants is considerably better and, furthermore, that the best bast is obtained from male plants.
Figure I. Hemp: a typical breakdown of the green and dry plant components
Source: M. J. Dempsey, Fiber crops (Gainesville, Florida, University Press of Florida, 1975), pp. 46-89.
Table 3. Qualitative properties of male, female and monoecious plants
| Cultivar | Fractions |
Fibre
(per-centage) |
Flexibility
HMM |
Torsional
resistance (10 3/T) |
Strength Pkp |
Metric
finesse (Nm) |
| Kompolti | Male | 31.5 | 26.8 | 19.31 | 6.16 | 141.72 |
| Female | 29.6 | 18.3 | 13.23 | 7.26 | 109.63 | |
| Male+
female |
30.4 |
24.3 |
16.78 |
6.04 |
131.23 |
|
| Fibrimont 21 | Monoecious | 26.7 | 16.0 | 11.80 | 6.25 | 101.25 |
Source: E. Horkay and I. Bócsa, "Objective basis for evaluation of differences in fibre quality between male, female and monoecious hemp", Journal of the International Hemp Association, vol. 2, No. 1 (1995), pp. 26-30, and vol. 3, No. 2 (1997), pp. 67 and 68.
Over the period 1985-1996 world production of paper products increased from 193.3 to 284.0 million tons, an average annual increase of 7.5 million tons.
Paper consumption is growing year after year. Today the deficit has reached chronic levels and natural, traditionally wood-based, internal resources are not able--and never will be able--to meet the continual increase in demand. In short, this is a global problem.
Recourse to paper recycling makes a contribution, although it also poses a problem in the utilization phase because of the lower quality of such recycled raw material. There is a growing need to supplement raw materials with pulps that have particularly resistant properties in order to withstand mechanical stresses both during the production stage and when paper is used in printing or for other purposes (packing, packaging, etc.) [10]. (See table 4.)
Table 4. Comparison of flax, hemp, ramie and jute textile characteristics
|
Flax
(dew-retted) |
Hemp
(dew-retted) |
Ramie
(de-gummed) |
Jute
(water-retted) |
|
| Dtex | 10-40 | 12-60 | 6-12 | 20-40 |
| Estimated wet spun (dernier) | 3-6 | 6-10 | 6-10 | 15-20 |
| Specific gravity | 1.43-1.5 | 1.45 | 1.5 | 1.4 |
| Extention at break (percentage) | 2 | 2 | 3 | 2 |
| Breaking strain CN/Dtex | 3.0-5.5 | 2.9-3.5 | 5.0-6.0 | 3.0-4.0 |
| Moisture regain | 8-12 | 8.5-12 | 10-12 | 13-14 |
| Average degree polymerization | 2 500 | 2 300 | 3 000 | 2 000 |
| Elementary fibre length (mm) | 20/25 | 10/40 | 125/130 | 2/3 |
| Fibre length as grown (metre) | 0.6-1 | 1.5-3 | 1.5-2 | 1.5-2 |
| Price (pre-hackling) per ton (US$) | 1 750 | 1 100 a | 2 000 | 500 |
| Lignin content (per-centage) | 2-3 | 6-8 | 2 | 16-20 |
Source: G. Mackie, "Hemp:
Cannabis sativa",
Proceedings of the Flax and Other Bast Plants Symposium, 30 September and 1 October 1997, Poznan, Poland, pp. 50-58.
a
Eastern Europe.
The best long-fibre paper pulp is obtained from the wood of conifers, species that grow mostly in northern regions of the globe. Furthermore, their economic cycle is extremely long, in the order of 80-120 years between planting and cutting. While research has led to development of rapid-growth conifer varieties and others that adapt to tropical and subtropical conditions, the contribution of the new types to industrial raw material production is still negligible.
Countries with large forestry resources by force of circumstance monopolize the market to the detriment of those countries completely lacking in that form of natural resource. It should also be borne in mind that pulp--or finished paper products--are paid for in hard currency and are therefore subject not only to varying market price trends but also to variations in exchange rates for the dollar. The negative impact of these factors severely affects poorer developing countries where the product paper = culture and knowledge = development. Unfortunately, the trend in such countries is to decrease rather than increase paper consumption as the years go by (see tables 5 and 6).
Annual fibre plants have long been considered a very interesting source of raw material for the paper industry. Some have already been used successfully in the past only to be abandoned, either for ecological reasons, as in the case of straw, or for economic reasons, as for hemp. Today, however, hemp and other fibre plant species such as kenaf, jute, ramie and sisal can well represent a new opportunity, both for the European and the worldwide pulp and paper industry.
Table 5. World paper consumption, 1985 and 1996
(Kilos per capita)
| Area | 1985 | 1996 |
Percentage
increase/(decrease) |
| Europe | 84.0 | 91.4 | 8.8 |
| North America | 282.6 | 310.1 | 9.7 |
| Asia | 16.5 | 26.7 | 61.8 |
| South America | 25.7 | 31.4 | 22.2 |
| Australasia | 120.8 | 145.1 | 20.1 |
| Africa | 5.7 | 5.4 | (5.2) |
Source: 1996 International Pulp and Paper Directory.
Table 6. Major paper consumer countries, 1985 and 1996
(Kilos per capita)
| Country | 1985 | 1996 |
Percentage
increase/(decrease) |
| Finland | 189 | 320 | 69.3 |
| United States of America | 284 | 319 | 12.3 |
| Belgium | 161 | 258 | 60.2 |
| Japan | 167 | 245 | 46.7 |
| Canada | 198 | 227 | 14.6 |
| Denmark | 171 | 215 | 25.7 |
| Switzerland | 178 | 209 | 17.4 |
| Netherlands | 170 | 204 | 20.0 |
| Sweden | 237 | 195 | (17.7) |
| Germany | 174 | 189 | 8.6 |
Source: 1996 International Pulp and Paper Directory.
On a worldwide basis pulp production from non-wood plant species still represents less than 10 per cent of the total, although it is growing considerably from year to year. Growth is double the rate of that recorded for all fibres and three times that of wood pulp alone. Today less than 6 per cent of the world's pulp manufacturers use hemp [11], and more than 77 per cent of the world's non-wood pulp production plants are concentrated in Asia, using for the most part by-products such as straw, bagasse or cotton linters (figures II and III).
Figure II. Geographical distribution of non-wood cellulose pulp production plants
Source: 1996 International Pulp and Paper Directory.
Adaptation of different hemp varieties to all latitudes between 0 and 7 N and S can represent an extremely important resource for many countries. They must, however, adopt new high-yield processing technology that utilizes the whole plant stem and focus on producing pulp for newsprint and writing paper. Pulp-processing plants that normally use hemp cellulose for production of cigarette, filter and other special papers would also benefit. Raw material would most probably be more abundant and no longer need to be imported but could instead be produced in their own national or regional territories.
The establishment of high-yield pulp plants in developing countries may however represent a problem due to the high cost of available energy when obtained from imported fuels. Fortunately research--conducted mainly on kenaf--has shown that energy consumption for pulp production from annual fibre plants would be less for all high-yield pulp processes.
A most important step forward will be the development of bio-pulping processes, a new type of process based on lignin degradation and separation of cellulose fibres by means of micro-organisms. This is a non-polluting process and energy consumption is significantly less. Furthermore, it is particularly valid for non-wood raw material from annual textile plants, among them hemp. Yields as high as 70-80 per cent have been forecast for hemp that has been well cleaned in a dry state before entering the reactor.
The steam explosion technique would also seem to offer new possibilities for treatment of hemp fibres based on tests carried out in the past on other plant species [12].
Figure III. Non-wood cellulose pulp production plants,
distribution according to raw material
Source: 1996 International Pulp and Paper Directory.
Then what are the prospects for hemp given the new processing technology? Apart from those pulp industry segments already using hemp cellulose, it is believed that hemp represents a hope in the future for the pulp sector as a whole. However, one problem that must be overcome is the length of the bast, a fibre many centimetres long in its natural form. This excessive length can lead to creasing or scoring defects in the pulp. One solution could be to cut up stems in the field using techniques now applied for kenaf in the United States of America, although this would probably complicate harvesting operations. It would therefore seem more opportune, given today's technology, to cut up the bast in production plants at the beginning of the pulp transformation process.
The use of the hurd as a raw material has recently been studied by V. S. Krotov at the Ukrainian Pulp and Paper Research Institute [13]. Applying the alcohol-based ammonia-sulphite (AAS) pulping process has produced pulps much superior to those obtained using the traditional soda and soda-anthraquinone (AQ) processes. In particular, yields are higher (from 54.5 to 67.9 per cent compared with 50.1 per cent and 46.5 per cent for soda and soda-AQ processes, respectively), while the breaking length (12,000 metres) is comparable with that of high-strength softwood kraft pulps. This latter characteristic, coupled with high tear strength, means that the hurd can be of considerable interest for production of high-grade bleachable pulp.
A recent feasibility study conducted by A. Ferting evaluated the use of entire hemp stems as a raw material for pulp in technological-economic terms [14]. This study clearly highlighted that adopting such an approach in order to substitute for conventional wood sources would be neither attractive from the technological standpoint nor economically viable. Indications are, therefore, that hemp should continue to play its traditional role as a raw material for pulp production of special papers. However, while a base price of DM 120 ($67) per ton for wood raw material may be considered realistic and economically viable for countries rich in pulp raw materials, it is certainly less so for countries with more modest or non-existent natural resources. This is particularly true in countries that intend to pursue environmental protection policies while still maintaining local pulp production for the reasons mentioned above.
Application of new high-yielding processing technologies can open up new prospects for hemp even though research in the area is rather recent and incomplete. Cooperation with industry would seem to be essential. In the light of recent EU statements regarding eligibility for the hemp crop subsidy, it appears essential that expansion of hemp cultivation be conducted in concert with industry, preferably on a contractual basis. This, in addition to guaranteeing that the product would be absorbed, would ensure that farmers receive just and agreed compensation for their efforts.
Certainly the pressure of public opinion towards adopting environmental protection policies will play an essential role in relaunching hemp. Hemp, and other textile crops cultivated at high density, have both a direct and an indirect effect on the environment: firstly, they lead to a reduction in the use of chemical weed-killers since weed growth is suppressed as a natural result of crop growth cycles; secondly, such crops represent a renewable source of raw material that can be programmed annually based on local industry production requirements.
Hemp seed is rich in oil, with a content for common varieties that varies between 26 and 35 per cent; an "oil-producing" Russian variety is reported to reach 40 per cent.
The seed also contains significant amounts of minerals and vitamins, in particular vitamin A, as well as proteins and various essential amino acids [6].
Table 7 highlights hemp seed oil's fatty acid content compared with other vegetable oils.
The high content in polyunsaturated fatty acids is significant. The linoleic acid content is particularly important from a dietary standpoint, especially the 3:1 ratio as compared with -linolenic acid. The latter serves as an intermediary for the formation of longer-chain fatty acids and eicosanoids, which fulfil numerous vital roles in the body [6].
As shown by recent research, the fatty acid percentage composition varies according to the variety's geographical origin. The most interesting spectrum of fatty acids for both the food and cosmetic industry would be those obtained from cold climate varieties (namely, from Poland, Russian Federation and Ukraine).
Table 7. Hemp seed compared with common edible oils
(Percentage of total fatty acids)
| Less healthy/chemically saturated | More nutritious/chemically unstable | ||||
| Mono-unsaturated | Polyunsaturated | ||||
|
Palmitic
C16:0 |
Stearic
C18:0 |
Oleic
C18:1w9 |
Linoleic
C18:2w6 |
Linolenic
C18:3w3 |
|
| Hemp | 6-9 | 2-3 | 10-16 | 50-70 | 15-20 |
| Soy | 9 | 6 | 26 | 50 | 7 |
| Canola | - | 7 | 54 | 30 | 7 |
| Wheatgerm | - | 18 | 25 | 50 | 5 |
| Safflower | - | 12 | 13 | 75 | - |
| Sunflower | - | 12 | 23 | 65 | - |
| Corn | - | 17 | 24 | 59 | - |
| Cotton seed | - | 25 | 21 | 50 | - |
| Sesame | - | 13 | 42 | 45 | - |
| Peanut | - | 18 | 47 | 29 | - |
| Avocado | - | 20 | 70 | 10 | - |
| Olive | - | 16 | 76 | 8 | - |
| Palm | 85 | - | 13 | 2 | - |
| Coconut | 91 | - | 6 | 3 | - |
Source: J. D. Deferne and D. W. Pate, "Hemp seed oil: a source oil; a source of valuable essential fatty acid", Journal of the International Hemp Association, vol. 3, No. 1 (1996), pp. 1-7.
Currently the only sure way to determine whether cannabis plants do or do not contain (tetrahydrocannabinol (THC) is by chemical analysis of single plants. However, throughout the world today there are no illicit crops comprising only monoecious plants and it is evident that a predominance of monoecious plants in a field of hemp can already be an indication that this is indeed a selected textile variety with low THC content. Clearly this empirical approach can only be adopted once plants have reached the flowering stage.
On the other hand, drug crop populations will also include examples of monoecious plants, sometimes with a THC content well in excess of 5 per cent. In the future, illicit drug producers could easily select and create populations comprising prevalently monoecious, drug-producing plants. To counteract such a development and to make control easier, a proposal was developed in 1990 [15] to create a variety of textile hemp containing practically no THC that would be marked genetically. What does this mean from a practical standpoint? Take the case where a plant belonging to the marked variety were to be fertilized by any other variety--whether textile or narcotic--and then the seed obtained were re-sown. All descendants from this seed would be plants exhibiting the typical characteristics of the non-genetically marked varieties. In fact these characteristics would be determined by the variety's dominant genetic features. They block any possibility of expression atypical to the variety itself as far as genetically non-dominant or recessive characteristics are concerned.
Starting in 1994, research financing was made available to the Institute for Industrial Crops in Bologna, Italy, to develop such a variety. The aim of the research is to provide farmers with hemp cultivars for which the intent to grow narcotic cannabis can be excluded.
Selection of monoecious varieties in Europe has in the past been based largely on research carried out by the Féderation nationale des producteurs de chanvre and by the Institut national de recherche agronomique, France, that has led to the development of EU-approved varieties with an average 0.15 per cent THC content.
One of the most recent developments has been the discovery of a gene that regulates the transformation of cannabigerol, a non-hallucinogenic cannabinoid intermediate [16], into -9-THC (see figure IV), the main hallucinogenic substance found in hemp [17]. That discovery has led to the creation of a new monoecious variety, Santhica 23, with a practically zero THC content. This variety, which has already been recorded in the European Varieties Register, is now ready to be marketed, although it has not been released to date.
In 1968, the Union decided to create a flax and hemp market organization to defend textile raw material production--materials that at that time were imported by member countries. In fact the EU textile sector had no tariff protection, as no duties were levied on imports of flax and hemp. This situation was further exacerbated by competition from American cotton, which in many cases entered the area at dumping prices. Efforts to ensure that the European textile industry could be supplied from internal resources instead of by imports led to authorization of subsidies in the form of a deficiency payment amounting to 10 per cent of textile crop production value.
It is important to note, however, that initially the above EU measures focused mainly on textile fibre and not seed production. EU Directive 1308 of 29 June 1970 established a policy that gave hemp and flax producers a lump-sum subsidy, at a level established year by year. Cotton was later admitted when Greece became a community member, since Greek cotton farmers had for many years benefited from a crop subsidy. While in fact hemp, flax and cotton producers all benefit from aid, references in the following paragraphs consider only the issue of fibre hemp.
Directive 1430/82 then took into consideration the fundamental problem of varying levels of cannabinoids present in hemp, depending on the particular variety. It was therefore established that aid under Directive 1308/70 would be limited to fibre hemp varieties with a low THC content. Based on the above directives and numerous other regulations introduced to integrate or modify them (see table 8), EU developed the intervention system summarized in outline below:
Figure IV. Biogenesis of cannabinoids
Source: G. Fournier, "Le chanvre et ses constituants", D. Thomas, Projet de démonstration : le chanvre textile (Le Mans, Comité économique agricole de la production de chanvre, 1990).
(a) Aid was made available only for hemp crops produced from certified seed chosen from among the varieties recorded in the European Varieties Register. The Register includes those varieties for which a member country has established that the THC content for a constant weight sample is no more than 0.3 per cent. A new proposal submitted recently to the Commission foresees reduction of the THC limit to 0.2 per cent as of the year 2002;
(b) The following varieties were those initially admitted for registration:
(i) Dioecious varieties
Carmagnola, CS, Fibranova--all of Italian origin;(ii) Monoecious varieties
Ferimon Fedora 19, Fibrimon 24, Fibrimon 56, Felina 34,
Fedrina 74, Futura--all of French origin;
Delta Illosa, Delta-405--Spanish, but registered by the French.
Later France registered two further monoecious varieties, Santhica 23 and Epsilon 56. More recently also Kompolti (Hungary), Benico (Poland), USO 31 (Ukraine) and Lovrin 110 (Romania) were registered;
(c) The analytical method giving a detailed description (THC content analysis in fibre hemp) was established, agreed upon and published in annex C to Directive 1164/89;
(d) Obligation as regards industrial transformation of production. The producer may deliver his hemp stem production to a third party for transformation or request transformation for his own account. Producers will qualify for subsidy in either case, provided that transformation is carried out by an authorized organization;
(e) By 1 August each year the amount for the lump-sum subsidy was established, to cover sales to be agreed in the following year. Aid was based on hectares sown and harvested and was awarded to member States, who were charged with the task of instituting administrative controls to ensure that crops for which aid was requested and granted complied with the authorized conditions;
(f) The introduction of a crop sowing authorization system has also recently been proposed. In order to reinforce controls a system may be introduced in the future that provides for preventive authorization for the sowing of hemp crops that will benefit from crop production subsidy;
(g) The latest move made within EU--a decision taken by the Council of Ministers on 6 June 1998--was to reduce the textile hemp crop subsidy by 7.5 per cent for the 1998/99 season.
Table 8. European Union Directives concerning hemp cultivation and aid
| Year | Directive | Subject |
| 1970 | 1308/70 | Common market organization for the flax and hemp sector |
| 1971 | 619/71 | General guidelines for aid concession regarding hemp and flax |
| 1982 | 1430/82 | Import restrictions on hemp bast and seed |
| 1984 | 2059/84 | Import restrictions on hemp bast and seed |
| 1984 | 2188/84 | Basic rules covering imports of hemp bast and seed |
| 1986 | 421/86 | Method for quantitative testing for THC in hemp |
| 1988 | 3698/88 | Special measures for hemp seed producers |
| 1989 | 1164/89 | Method of applying for textile flax and hemp aid |
| 1989 | 1496/89 | Sampling checks for declared cultivated areas |
| 1989 | 3164/89 | Special measures for aid concession to hemp seed producers |
| 1990 | 1870/90 | Target price for flax and hemp aid reduced due to monetary alignment |
| 1990 | 2218/90 | Prices fixed in ecus for the textile fibre sector due to monetary alignment |
| 1991 | 504/91 | Indicative yields for hemp seed as regards the 1990/1991 campaign |
| 1992 | 2296/92 | Use of set-aside land for non-food industrial raw material production |
| 1993 | 2044/93 | Prices fixed in ecus for the textile fibre sector due to monetary alignment |
| 1995 | 1741/95 | Certified seed documentation, minimum seed development at start of harvesting |
| 1996 | 466/96 | Textile flax and hemp aid: modifies Directive 1164/89--inclusion of new varieties |
Italy has a long tradition of hemp cultivation destined mainly for the production of quality yarn. Up until the late 1940s Italy was the world's second largest producer, after the Union of Soviet Socialist Republics, and the leading exporting nation. Numerous Italian varieties existed that gave high-quality results, but all of these were dioecious. Hemp production in Italy was abandoned almost 20 years ago.
For the 1998/99 season, within the framework of a programme to relaunch hemp production, the Government of Italy has authorized the cultivation of 1,000 hectares of fibre hemp. That programme, in cooperation with French hemp producer organizations, will include activities to create seed stock and obtain certification for Italian dioecious varieties already recorded in the European Varieties Register but which have since disappeared from the seed market: Carmagnola, CS and Fibranova. Attempts will also be made to recover and present other Italian dioecious varieties for certification, such as Superfibra and Eletta Campana.
Although the ideal time to harvest stems for textile as opposed to raw material for pulp is different, seed production for the different industries could be carried out simultaneously. As regards raw material for pulp, completion of the plant's physiological cycle up to seed maturity does not damage fibre quality significantly. While production today is mainly from monoecious varieties, dioecious varieties could also be used since the presence of dead male plants in a crop (because of their shorter vegetative cycle) would not have a negative effect on the quality of the raw material for pulp.
The same cannot be said for bast produced for the textile industry. To obtain quality textile fibre, plants must always be harvested at the end of the male plant flowering cycle. J. M. Dempsey, a leading United States expert on fibre plants, states that it is very important to harvest hemp at the right moment in order to ensure better fibre quality. He quotes Bellini [18]:
"Dioecious hemp should be harvested when the leaves and stems of the male plants become yellow and when a fading of the inflorescence denotes that pollen scattering has ceased. At this time both male and female plants will have shed the leaves from the lower two thirds of the stems, but the remaining leaves on the female plants will be dark green and glossy."
Unfortunately, as far as hemp for the textile industry is concerned, the plant's biological cycle is at odds with EU regulations. Modifications made to article 4 of Directive 1164/89 would appear to distort the aims originally pursued by EU. Initially the intent was merely to defend cultivation of traditional European textile species, including harvesting of seed. In effect, whereas article 4 of Directive 1164/89 stated:
"Aid is conceded only for areas: (a) where sowing and harvesting have been carried out and regarding which normal crop activities have been performed; (b) that are included in the declaration concerning areas to be sown in accordance with article 5",
later modifications to the above article as a result of Directives 1741/95 and 466/96 established eligibility for aid only when the number of seeds that have reached their definitive form and volume is greater than the others remaining, in practice, when more than 50 per cent of the seeds are mature. Conflict with the original intent of article 4, which only required that normal crop activities had been performed, is evident. Later modifications made to article 4--perhaps as a result of aid being linked only to the area cultivated--penalizes production of high-quality bast, a product the European textile industry is crying out for. The end result of EU regulations, as modified in 1995 and 1996, will be to obstruct production of high-quality textile hemp bast.
Indeed, there is a definite risk that current regulations will promote abuse, since it will be easier to employ low THC content hemp to hide high THC content plants, given that the latter must grow through to full seed maturity, which is when they reach their highest levels of THC content (see figure V) for marijuana or hashish production. As regards monoecious varieties, almost simultaneous flowering of all plants means that it is easier to identify and distinguish licit from illicit crops, at least when the plants are in the flowering stage.
Figure V. The development of tetrahydrocannabinol (THC) content in cannabis during the vegetative cycle
Source: M. Frank and E. Roseland, Marijuana Grower's Guide (Berkeley, 1978).
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