Hemp: A New Crop with New Uses for North America*
Ernest Small and David Marcus
*This paper was considerably improved by criticism provided by A. McElroy.
“Hemp” refers primarily to
Cannabis sativa L. (Cannabaceae), although
the term has been applied to dozens of species representing at least 22 genera,
often prominent fiber crops. For examples, Manila hemp (abaca) is
Musa
textilis Née, sisal hemp is
Agave sisalina Perrine, and sunn hemp is
Crotolaria juncea L. Especially confusing is the phrase “Indian hemp,”
which has been used both for narcotic Asian land races of
C. sativa
(so-called
C. indica Lamarck of India) and
Apocynum cannabinum L.,
which was used by North American Indians as a fiber plant.
Cannabis
sativa is a multi-purpose plant that has been domesticated for bast (phloem)
fiber in the stem, a multi-purpose fixed oil in the “seeds” (achenes), and an
intoxicating resin secreted by epidermal glands. The common names hemp and
marijuana (much less frequently spelled marihuana) have been applied loosely to
all three forms, although historically hemp has been used primarily for the
fiber cultigen and its fiber preparations, and marijuana for the drug cultigen
and its drug preparations. The current hemp industry is making great efforts to
point out that “hemp is not marijuana.” Italicized,
Cannabis refers to
the biological name of the plant (only one species of this genus is commonly
recognized,
C. sativa L.). Non-italicized, “cannabis” is a generic
abstraction, widely used as a noun and adjective, and commonly (often loosely)
used both for cannabis plants and/or any or all of the intoxicant preparations
made from them.
Probably indigenous to temperate Asia,
C. sativa is the most widely
cited example of a “camp follower.” It was pre-adapted to thrive in the manured
soils around man’s early settlements, which quickly led to its domestication
(Schultes 1970). Hemp was harvested by the Chinese 8500 years ago (Schultes and
Hofmann 1980). For most of its history,
C. sativa was most valued as a
fiber source, considerably less so as an intoxicant, and only to a limited
extent as an oilseed crop. Hemp is one of the oldest sources of textile fiber,
with extant remains of hempen cloth trailing back 6 millennia. Hemp grown for
fiber was introduced to western Asia and Egypt, and subsequently to Europe
somewhere between 1000 and 2000
BCE. Cultivation in Europe
became widespread after 500 ce. The crop was first brought to South America in
1545, in Chile, and to North America in Port Royal, Acadia in 1606. The hemp
industry flourished in Kentucky, Missouri, and Illinois between 1840 and 1860
because of the strong demand for sailcloth and cordage (Ehrensing 1998). From
the end of the Civil War until 1912, virtually all hemp in the US was produced
in Kentucky. During World War I, some hemp cultivation occurred in several
states, including Kentucky, Wisconsin, California, North Dakota, South Dakota,
Minnesota, Indiana, Illinois, Ohio, Michigan, Kansas, and Iowa (Ehrensing 1998).
The second world war led to a brief revival of hemp cultivation in the Midwest,
as well as in Canada, because the war cut off supplies of fiber (substantial
renewed cultivation also occurred in Germany for the same reason). Until the
beginning of the 19th century, hemp was the leading cordage fiber. Until the
middle of the 19th century, hemp rivaled flax as the chief textile fiber of
vegetable origin, and indeed was described as “the king of fiber-bearing
plants,—the standard by which all other fibers are measured” (Boyce 1900).
Nevertheless, the Marihuana Tax Act applied in 1938 essentially ended hemp
production in the United States, although a small hemp fiber industry continued
in Wisconsin until 1958. Similarly in 1938 the cultivation of
Cannabis
became illegal in Canada under the Opium and Narcotics Act.
Hemp, grown under license mostly in Canada, is the most publicized “new” crop
in North America. Until very recently the prohibition against drug forms of the
plant prevented consideration of cultivation of fiber and oilseed cultivars in
Canada. However, in the last 10 years three key developments occurred: (1)
much-publicized recent advances in the legal cultivation of hemp in western
Europe, especially for new value-added products; (2) enterprising farmers and
farm groups became convinced of the agricultural potential of hemp in Canada,
and obtained permits to conduct experimental cultivation; and (3) lobby groups
convinced the government of Canada that narcotic forms of the hemp plant are
distinct and distinguishable from fiber and oilseed forms. In March 1998, new
regulations (under the Controlled Drugs and Substances Act) were provided to
allow the commercial development of a hemp industry in Canada, and since then
more than a thousand licenses have been issued. Hectares licensed for
cultivation for 1998–2001 were respectively, 2,500, 14,200, 5,487, and 1,355,
the decreasing trend due to a glut of seed produced in 1999 and pessimism over
new potential regulations barring exports to the US. Information on the
commercial potential of hemp in Canada is in Blade (1998), Marcus (1998), and
Pinfold Consulting (1998). In the US, a substantial trade in hemp products has
developed, based on imports of hemp fiber, grain, and oil. The American
agricultural community has observed this, and has had success at the state level
in persuading legislators of the advisability of experimental hemp cultivation
as a means of evaluating the wisdom of re-establishing American hemp production.
However, because of opposition by the federal government, to date there has only
been a small experimental plot in Hawaii. Information on the commercial
potential of hemp in the US is presented in the following.
Cannabis sativa is extremely unusual in the diversity of products for
which it is or can be cultivated. Popular Mechanics magazine (1938) touted hemp
as “the new billion dollar crop,” stating that it “can be used to produce more
than 25,000 products, ranging from dynamite to Cellophane.” Table 1 presents the
principal products for which the species is cultivated in Europe, all of which
happen to be based on fiber. This presentation stresses the products that hold
the most promise for North America, which also include a considerable range of
oilseed applications (Table 2; Fig. 1).
Table 1. Hemp fiber usage in the European Union in 1999 (after Karus
et al. 2000).
| Class of product |
Quantity
consumed
(tonnes) |
Relative
percentage |
| Specialty pulp (cigarette paper, bank notes, technical filters, and hygiene
products) |
24,882 |
87 |
| Composites for autos |
1,770 |
6 |
| Construction & thermal insulation materials |
1,095 |
4 |
| Geotextiles |
234 |
0.8 |
| Other |
650 |
2.2 |
| Total |
26,821 |
100 |
Table 2. Analysis of commercial
Cannabis product potential in
North America in order of decreasing value toward the right and toward the
bottom.
| Seeds (achenes) |
Long ("bark) fiber |
Woody stem core |
Female floral (perigonal) bract |
Whole plant |
| Confectionary, baked goods |
Plastic-molded products |
Animal bedding |
Medicinal cannabinoids |
Alcohol |
| Salad oil |
Specialty papers |
Thermal insulation |
Essential oil (for flavor & perfume) |
Fuel |
| ody care "cosmetics |
Construction fiberboard |
Construction (fiberboard, plaster board, etc.) |
Insect repellant |
Silage |
| Animal food (whole seeds for birds, presscake for mammalian livestock) |
Biodegradable landscape matting & plant culture products |
|
|
|
| Gamma-linolenic acid dietary supplements |
Coarse textiles (carpets, upholstery) |
|
|
|
| Specialty industrial oils |
Fine textiles |
|
|
|
Fig. 1. Major uses of industrial hemp.
BASIC CATEGORIES OF CANNABIS AND THEIR FIELD ARCHITECTURE
Cannabis sativa is an annual wind-pollinated plant, normally dioecious
and dimorphic, although sometimes monoecious (mostly in several modern European
fiber cultivars). Figure 2 presents the basic morphology of the species. Some
special hybrids, obtained by pollinating females of dioecious lines with pollen
from monoecious plants, are predominantly female (so-called “all-female,” these
generally also produce some hermaphrodites and occasional males). All-female
lines are productive for some purposes (e.g. they are very uniform, and with
very few males to take up space they can produce considerable grain), but the
hybrid seed is expensive to produce. Staminate or “male” plants tend to be
10%–15% taller and are less robust than the pistillate or “female” (note the
comparatively frail male in Fig. 3). So prolific is pollen production that an
isolation distance of about 5 km is usually recommended for generating pure-bred
foundation seed. A “perigonal bract” subtends each female flower, and grows to
envelop the fruit. While small, secretory, resin-producing glands occur on the
epidermis of most of the above-ground parts of the plant, the glands are very
dense and productive on the perigonal bracts, which are accordingly of central
interest in marijuana varieties. The root is a laterally branched taproot,
generally 30–60 cm deep, up to 2.5 m in loose soils, very near the surface and
more branched in wet soils. Extensive root systems are key to the ability of
hemp crops to exploit deep supplies of nutrients and water. The stems are erect,
furrowed, and usually branched, with a woody interior, and may be hollow in the
internodes. Although the stem is often woody, the species is frequently referred
to as a herb or forb. Plants vary enormously in height depending on genetic
constitution and environment (Fig. 4), but are typically 1–5 m (heights of 12 m
or more in cultivation have been claimed).
Fig. 2. Cannabis sativa. This superb composite plate by artist
Elmer Smith, often reproduced at a very small scale and without explanation in
marijuana books, is the best scientific illustration of the hemp plant ever
prepared. 1. Flowering branch of male plant. 2. Flowering branch of female
plant. 3. Seedling. 4. Leaflet. 5. Cluster of male flowers. 6. Female flower,
enclosed by perigonal bract. 7. Mature fruit enclosed in perigonal bract. 8.
Seed (achene), showing wide face. 9. Seed, showing narrow face. 10. Stalked
secretory gland. 11. Top of sessile secretory gland. 12. Long section of
cystolith hair (note calcium carbonate concretion at base). Reproduced with the
permission of Harvard University, Cambridge, MA.
 |
 |
| Fig. 3. Photograph of Cannabis sativa. Left,
staminate (“male”) plant in flower; right, pistillate (“female”) plant in
flower. |
Fig. 4. United States National Institute of Health,
University of Mississippi marijuana plantation site, showing variation in plant
size. A tall fiber-type of hemp plant is shown at left, and a short narcotic
variety (identified as “Panama Gold”) at right. |
There is great variation in
Cannabis sativa, because of disruptive
domestication for fiber, oilseed, and narcotic resin, and there are features
that tend to distinguish these three cultigens (cultivated phases) from each
other. Moreover, density of cultivation is used to accentuate certain
architectural features. Figure 5 illustrates the divergent appearances of the
basic agronomic categories of
Cannabis in typical field
configurations.
Fig. 5. Typical architecture of categories of cultivated
Cannabis
sativa. Top left: narcotic plants are generally low, highly branched, and
grown well-spaced. Top right: plants grown for oilseed were traditionally
well-spaced, and the plants developed medium height and strong branching. Bottom
left: fiber cultivars are grown at high density, and are unbranched and very
tall. Bottom center: “dual purpose” plants are grown at moderate density, tend
to be slightly branched and of medium to tall height. Bottom right: some recent
oilseed cultivars are grown at moderate density and are short and relatively
unbranched. Degree of branching and height are determined both by the density of
the plants and their genetic background.
Highly selected forms of the fiber cultigen possess features maximizing fiber
production. Since the nodes tend to disrupt the length of the fiber bundles,
thereby limiting quality, tall, relatively unbranched plants with long
internodes have been selected. Another strategy has been to select stems that
are hollow at the internodes, with limited wood, since this maximizes production
of fiber in relation to supporting woody tissues. Similarly, limited seed
productivity concentrates the plant’s energy into production of fiber, and fiber
cultivars often have low genetic propensity for seed output. Selecting
monoecious strains overcomes the problem of differential maturation times and
quality of male (staminate) and female (pistillate) plants (males mature 1–3
weeks earlier). Male plants in general are taller, albeit slimmer, less robust,
and less productive. Except for the troublesome characteristic of dying after
anthesis, male traits are favored for fiber production, in contrast to the
situation for drug strains noted below. In former, labor-intensive times, the
male plants were harvested earlier than the females, to produce superior fiber.
The limited branching of fiber cultivars is often compensated for by possession
of large leaves with wide leaflets, which obviously increase the photosynthetic
ability of the plants. Since fiber plants have not generally been selected for
narcotic purposes, the level of intoxicating constituents is usually
limited.
An absence of such fiber-strain traits as tallness, limited branching, long
internodes, and very hollow stems, is characteristic of narcotic strains. Drug
forms have historically been grown in areas south of the north-temperate zone,
often close to the equator, and are photoperiodically adapted to a long season.
When grown in north-temperate climates maturation is much-delayed until late
fall, or the plants succumb to cold weather before they are able to produce
seeds. Unlike fiber strains that have been selected to grow well at extremely
high densities, drug strains tend to be less persistent when grown in high
concentration (de Meijer 1994). Drug strains can be very similar in appearance
to fiber strains. However, a characteristic type of narcotic plant was selected
in southern Asia, particularly in India and neighboring countries. This is
dioecious, short (about a meter in height), highly branched, with large leaves
(i.e. wide leaflets), and it is slow to mature. The appearance is rather like a
short, conical Christmas tree.
Until recent times, the cultivation of hemp primarily as an oilseed was
largely unknown, except in Russia. Today, it is difficult to reconstruct the
type of plant that was grown there as an oilseed, because such cultivation has
essentially been abandoned. Oilseed hemp cultivars in the modern sense were not
available until very recently, but some land races certainly were grown
specifically for seeds in Russia. Dewey (1914) gave the following information:
“The short oil-seed hemp with slender stems, about 30 inches high, bearing
compact clusters of seeds and maturing in 60 to 90 days, is of little value for
fiber production, but the experimental plants, grown from seed imported from
Russia, indicate that it may be valuable as an oil-seed crop to be harvested and
threshed in the same manner as oil-seed flax.” Most hemp oilseed in Europe is
currently obtained from so-called “dual usage” plants (employed for harvest of
both stem fiber and seeds, from the same plants). Of the European dual-usage
cultivars, ‘Uniko B’ and ‘Fasamo’ are particularly suited to being grown as
oilseeds. Very recently, cultivars have been bred specifically for oilseed
production. These include ‘Finola,’ formerly known as ‘Fin-314’ (Fig. 6) and
‘Anka’ (Fig. 7), which are relatively short, little-branched, mature early in
north-temperate regions, and are ideal for high-density planting and harvest
with conventional equipment. Dewey (1914) noted that a Turkish narcotic type of
land race called “Smyrna” was commonly used in the early 20th century in the US
to produce birdseed, because (like most narcotic types of
Cannabis) it is
densely branched, producing many flowers, hence seeds. While oilseed land races
in northern Russia would have been short, early-maturing plants in view of the
short growing season, in more southern areas oilseed landraces likely had
moderate height, and were spaced more widely to allow abundant branching and
seed production to develop. Until Canada replaced China in 1998 as a source of
imported seeds for the US, most seeds used for various purposes in the US were
sterilized and imported from China. Indeed, China remains the largest producer
of hempseed. We have grown Chinese hemp land races, and these were short,
branched, adapted to a very long growing season (i.e. they come into flower very
slowly in response to photoperiodic induction of short days in the fall), and
altogether they were rather reminiscent of Dewey’s description of Smyrna.
Although similar in appearance to narcotic strains of
C. sativa, the
Chinese land races we grew were in fact low in intoxicating constituents, and it
may well be that what Dewey thought was a narcotic strain was not. Although some
forms of
C. sativa have quite large seeds, until recently oilseed forms
appear to have been mainly selected for a heavy yield of seeds, usually
recognizable by abundant branching. Such forms are typically grown at lower
densities than hemp grown only for fiber, as this promotes branching, although
it should be understood that the genetic propensity for branching has been
selected. Percentage or quality of oil in the seeds does not appear to have been
important in the past, although selection for these traits is now being
conducted. Most significantly, modern selection is occurring with regard to
mechanized harvesting, particularly the ability to grow in high density as
single-headed stalks with very short branches bearing considerable seed.
 |
 |
| Fig. 6. ‘Finola,’ the first cultivar of Cannabis
sativa bred exclusively for grain. (Courtesy of the breeder, J.C. Callaway,
Univ. Kuopio, Finland.) |
Fig. 7. ‘Anka,’ the first registered North American bred
cultivar of Cannabis sativa. This variety is best suited for grain
production. (Courtesy of the breeder, P. Dragla, and of the Industrial Hemp Seed
Development Company, Chatham, Ontario.) |
CONTROLLING THE DRUG ABUSE POTENTIAL OF HEMP
As detailed below, the development of hemp as a new legal crop in North
America must be considered in relation to illicit cultivation, so it is
important to appreciate the scope of the drug situation. Up until the first half
of the 20th century, drug preparations of
Cannabis were used
predominantly as a recreational inebriant in poor countries and the lower
socio-economic classes of developed nations. After World War II, marijuana
became associated with the rise of a hedonistic, psychedelic ethos, first in the
United States and eventually over much of the world, with the consequent
development of a huge international illicit market that exceeds the value of the
hemp market during its heyday. Table 3 shows the “economic significance”
(dollars generated in the black market plus dollar cost of control measures) of
the illicit drug industry associated with
C. sativa, and contrasts this
with the estimated dollar value of major categories of legitimate uses. In the
Netherlands, the annual value of narcotic hemp cultivation (ca. $10 billion)
exceeds the value of tulips (Collins 1999). Marijuana has become the most widely
disseminated illicit species in the world (Schultes and Hofmann 1980). With the
exception of alcohol, it is the most widely used recreational euphoric drug.
About 25% of North Americans are believed to have used
Cannabis
illegally. According to the US National Institute on Drug Abuse
(www.nida.nih.gov/Infofax/marijuana.html), more than 72 million Americans (33%)
12 years of age and older have tried marijuana. Cultivation, commerce, and
consumption of drug preparations of
Cannabis have been proscribed in most
countries during the present century. The cost of enforcing the laws against
Cannabis in North America is in the billions of dollars annually. In
addition, there are substantial social costs, such as adverse effects on users,
particularly those who are convicted. Tragically this includes some legitimate
farmers who, faced with financial ruin because of the unprofitability of crops
being grown, converted to growing marijuana.
Table 3. Comparative annual world economic significance of categories
of
Cannabis activity.
| Category |
World ($) |
North America ($) |
Type of investment |
| Recreational drugs |
> 1 trillion |
100s of billions |
Law enforcement, eradication, education |
| Industrial hemp |
100s of millionsz |
10s of millions |
Production, development, marketing, research |
| Therapeutic drugs |
100s of millions |
10s of millions |
Production, development, marketing, research |
| Phytoremediation |
10s of thousands |
nil |
Research |
| Ornamental hemp |
thousands |
nil |
Development |
z“The global market for hemp-derived products is valued at between
$100 million and $200 million annually” (Pinfold Consulting 1998; De Guzman
2001).
A rather thorough analysis of the scope of the illicit marijuana industry in
Canada for 1998 is reported at
www.rcmp-grc.gc.ca/html/drugsituation.htm#Marihuana and summarized in MacLeod
(1999). At least 800 tonnes (t) of marijuana were grown in Canada in 1998,
representing a harvest of 4.7 million flowering plants. More than 50% of the
marijuana available in Canada is grown domestically. An average mature plant was
estimated to produce 170 g of “marketable substance.” The value of the Canadian
crop is uncertain, but has been estimated to be in the billions of dollars
annually (Heading 1998; MacLeod 1999).
The US Drug Enforcement Administration’s online criminal justice statistics
for 2000 (cscmosaic.albany.edu/sourcebook/1995/pdf/t440.pdf) shows the following
seizures and eradication of plants of
C. sativa: 40,929 outdoor plots
(2,597,796 plants), 139,580,728 ditchweed (ruderal plants), 2,361 indoor
operations (217,105 plants), for a grand total of 2,814, 903 plants destroyed.
Impressively, the species was grown in all 50 states (including outdoor seizures
in every state except Wyoming)! It is of course impossible to know exactly how
much marijuana is cultivated in the United States, and perhaps only 10% to 20%
of the amount grown is seized. The profitability of the illegal crop is
indicated by a comparison of the cost of a bushel of corn (roughly $2.50) and a
bushel of manicured marijuana (about $70,000; it has been suggested that prices
range from $500 a pound, for low-quality marijuana, to more than $5,000 a pound
for “boutique” strains like “Northern Lights” and “Afghan Kush”). According to a
National Organization for the Reform of Marijuana Laws (NORML)
(mir.drugtext.org/marijuananews/marijuana_ranks_fourth_largest_c.htm) marijuana
is at least the fourth most valuable crop in America, outranked only by corn,
soybeans, and hay. It was estimated that 8.7 million marijuana plants were
harvested in 1997, worth $15.1 billion to growers and $25.2 billion on the
retail market (the wholesale value was used to compare marijuana to other cash
crops). Marijuana was judged to be the largest revenue producing crop in
Alabama, California, Colorado, Hawaii, Kentucky, Maine, Rhode Island, Tennessee,
Virginia, and West Virginia, and one of the top five cash crops in 29 other
states.
Cannabis contains a seemingly unique class of chemicals, the
cannabinoids, of which more than 60 have been described, but only a few are
psychoactive. Cannabinoids are produced in specialized epidermal glands, which
differ notably in distribution on different organs of the plant (high
concentrations occur on the upper surface of the young leaves and young twigs,
on the tepals, stamens, and especially on the perigonal bract). Given this
distribution, the glands would seem to be protective of young and reproductive
above-ground tissues (the roots lack glands). Two classes of epidermal glands
occur—stalked and sessile (Fig. 8), but in either case the glandular cells are
covered by a sheath under which resin is accumulated, until the sheath ruptures,
releasing resin on the surface. The resin is a sticky mixture of cannabinoids
and a variety of terpenes. The characteristic odor of the plant is due to the
abundant terpenes, which are not psychoactive. The more important cannabinoids
are shown in Fig. 9. In the plant the cannabinoids exist predominantly in the
form of carboxylic acids, which decarboxylate with time or when heated.
Delta-9-tetrahydrocannabinol (
D9-THC, or
simply THC) is the predominant psychoactive component. Other THC isomers also
occur, particularly
D8-THC, which is also
psychoactive. Technically, the euphoric psychological effects of THC are best
described by the word psychotomimetic. Cannabidiol (CBD) is the chief
non-psychotomimetic cannabinoid. A THC concentration in marijuana of
approximately 0.9% has been suggested as a practical minimum level to achieve
the (illegal) intoxicant effect, but CBD (the predominant cannabinoid of fiber
and oilseed varieties) antagonizes (i.e. reduces) the effects of THC
(Grotenhermen and Karus 1998). Concentrations of 0.3% to 0.9% are considered to
have “only a small drug potential” (Grotenhermen and Karus 1998). Some
cannabinoid races have been described, notably containing cannabichromene
(particularly in high-THC forms) and cannabigerol monomethyl ether (in some
Asian strains). The biosynthetic pathways of the cannabinoids are not yet
satisfactorily elucidated, although the scheme shown in Fig. 10 is commonly
accepted. At least in some strains, THC is derived from cannabigerol, while in
others it may be derived from CBD. CBN and
D8-THC are considered to be degradation products
or analytical artifacts (Pate 1998a).
 |
 |
| Fig. 8. Scanning electron micrographs of the abaxial
surface of a perigonal bract (which envelops the fruit). These bracts are the
most intoxicating part of the plant, and may contain 20% THC, dry weight. The
resin is synthesized both in stalked and sessile glands. Multicellular secretory
glands (of phallic appearance), some broken stalks of these (note cellular
appearance), and unicellular cystolith hairs (claw-like structures) are
pictured. |
Fig. 9. Some important cannabinoids of cannabis resin.
D9-THC (delta-9 tetrahydrocannabinol) is the
chief intoxicant chemical and predominates in intoxicant strains, while the
isomer D8-THC is usually present in no more
than trace amounts. CBD (cannabidiol) is the chief non-intoxicant chemical, and
predominates in non-intoxicant strains; it has sedative effects. The
non-intoxicant CBN (cannabinol) is a frequent degradation or oxidation product.
The non-intoxicant cannabichromene (CBC) is typically found in trace amounts in
intoxicant strains. The non-intoxicant cannabigerol (CBG) is considered to be a
precursor of the other cannbinoids (see Fig. 10). |
Fig. 10. Proposed biosynthetic pathways of the principal cannabinoids
(after Pate 1998b).
Both in Canada and the US, the most critical problem to be addressed for
commercial exploitation of
C. sativa is the possible unauthorized drug
use of the plant. Indeed, the reason hemp cultivation was made illegal in North
America was concern that the hemp crop was a drug menace. The drug potential is,
for practical purposes, measured by the presence of THC. THC is the world’s most
popular illicit chemical, and indeed the fourth most popular recreational drug,
after caffeine, alcohol, and nicotine. “Industrial hemp” is a phrase that has
become common to designate hemp used for commercial non-intoxicant purposes.
Small and Cronquist (1976) split
C. sativa into two subspecies:
C.
sativa subsp.
sativa, with less than 0.3% (dry weight) of THC in the
upper (reproductive) part of the plant, and
C. sativa subsp.
indica (Lam.) E. Small & Cronq. with more than 0.3% THC. This
classification has since been adopted in the European Community, Canada, and
parts of Australia as a dividing line between cultivars that can be legally
cultivated under license and forms that are considered to have too high a drug
potential. For a period, 0.3% was also the allowable THC content limit for
cultivation of hemp in the Soviet Union. In the US, Drug Enforcement Agency
guidelines issued Dec. 7, 1999 expressly allowed products with a THC content of
less than 0.3% to enter the US without a license; but subsequently permissible
levels have been a source of continuing contention. Marijuana in the illicit
market typically has a THC content of 5% to 10% (levels as high as 25% have been
reported), and as a point of interest, a current Canadian government
experimental medicinal marijuana production contract calls for the production of
6% marijuana. As noted above, a level of about 1% THC is considered the
threshold for marijuana to have intoxicating potential, so the 0.3% level is
conservative, and some countries (e.g. parts of Australia, Switzerland) have
permitted the cultivation of cultivars with higher levels. It should be
appreciated that there is considerable variation in THC content in different
parts of the plant. THC content increases in the following order: achenes
(excluding bracts), roots, large stems, smaller stems, older and larger leaves,
younger and smaller leaves, flowers, perigonal bracts covering both the female
flowers and fruits. It is well known in the illicit trade how to screen off the
more potent fractions of the plant in order to increase THC levels in resultant
drug products. Nevertheless, a level of 0.3% THC in the flowering parts of the
plant is reflective of material that is too low in intoxicant potential to
actually be used practically for illicit production of marijuana or other types
of cannabis drugs. Below, the problem of permissible levels of THC in food
products made from hempseed is discussed.
There is a general inverse relationship in the resin of
Cannabis
between the amounts of THC present and the amount of the other principal
cannabinoid, CBD. Whereas most drug strains contain primarily THC and little or
no CBD, fiber and oilseed strains primarily contain CBD and very little THC. CBD
can be converted to THC by acid catalyzed cyclization, and so could serve as a
starting material for manufacturing THC. In theory, therefore, low-THC cultivars
do not completely solve the problem of drug abuse potential. In practice,
however, the illicit drug trade has access to easier methods of synthesizing THC
or its analogues than by first extracting CBD from non-drug hemp strains.
Breeding for low THC cultivars in Europe has been reviewed by Bócsa (1998),
Bócsa and Karus (1998), and Virovets (1996). Some researchers have claimed to
have produced essentially THC-free strains, although at present no commercial
cultivar seems to be 100% free of THC. THC content has proven to be more easily
reduced in monoecious than in dioecious varieties. It should be possible to
select THC-free strains, and there has been speculation that genetic engineering
could be helpful in this regard. As a strategic economic and political tactic,
France has been attempting for several years to have the European Union (EU)
adopt legislation forbidding the cultivation of industrial hemp cultivars with
more than 0.1% THC, which would mean that primarily French varieties would have
to be cultivated in Europe. However, the Canadian government has found that some
French material has proven to be excessively high in THC.
There is certainly a need to utilize available germplasm sources in order to
breed suitable cultivars for North America. A list of the 24 approved cultivars
for the 2001 season in Canada is at
www.hc-sc.gc.ca/hpb-dgps/therapeut/htmleng/hemp.html. Most of these are
regulated by the European Organization of Economic Cooperation and Development
(OECD). These cultivars are “approved” for use in Canada not on agricultural
criteria, but merely on the basis that they meet the THC criterion. Indeed, most
of these are unsuitable or only marginally suitable for Canada (Small and Marcus
2000), and only a very few Canadian cultivars to date have been created. In
Canada, every acquisition of hemp grown at a particular place and time must be
tested for THC content by an independent laboratory and, under the industrial
hemp regulations, fields of hemp with more than 0.3% THC may require destruction
(a slight degree of flexibility is generally exercised). Importation of
experimental hemp lines (i.e. other than the approved cultivars) requires
importation licenses (as well as phytosanitary clearance of the shipment by the
Canadian Food Inspection Agency), and the importation licenses require an
indication that the THC contents are low.
In Canada, the methodology used for analyses and sample collection for THC
analysis of hemp plantings is standardized (at the Health Canada/Therapeutics
Program/Hemp web site at www.hc-sc.gc.ca/hpb-dgps/therapeut/htmleng/hemp.html,
see “Industrial Hemp Technical Manual” for procedures on sampling plant
materials and chemical procedures for determining THC levels). The regulations
require that one of the dozen independent laboratories licensed for the purpose
conduct the analyses and report the results to Health Canada. Sample collection
is also normally carried out by an independent authorized firm. The Canadian
system of monitoring THC content has rigidly limited hemp cultivation to
cultivars that consistently develop THC levels below 0.3%.
Because
C. sativa has been a neglected crop for so long in North
America, there are only negligible genetic resources available on this
continent. Most germplasm stocks of hemp are in Europe, and the largest and most
important collection is the Vavilov Institute gene bank in Leningrad. Figure 11
shows THC concentrations in the Vavilov collection, as well as in our own
collection, largely of European germplasm. A disturbingly high percentage of the
collections have THC levels higher than 0.3%, making it difficult to incorporate
these into breeding programs.
Fig. 11. Frequency histograms of THC concentration in germplasm
collections. Left, collection of E. Small and D. Marcus; of the 167 accessions,
43% had THC levels >0.3%. Right, the collection of the Vavilov Institute, St.
Petersburg; of the 278 accessions for which chemical analyses were reported in
Anonymous (1975), about 55% had THC levels >0.3%.
Soil characteristics, latitude and climatic stresses have been found to have
significant effects on THC concentrations, and there are seasonal and even
diurnal variations (Small 1979; Pate 1998b). However, the range of THC
concentrations developed by low-THC cultivars (those typically with £0.3% THC)
under different circumstances on the whole is limited, for the most part
generally not varying more than 0.2 percentage points when grown in a range of
circumstances, and usually less (note information in Scheifle et al. 1999;
Scheifle 2000, Scheifle and Dragla 2000). Practically, this has meant in
Canadian experience that a few cultivars have been eliminated from further
commercial cultivation because they sometimes exceed the 0.3% level (‘Fedora 19’
and ‘Futura,’ authorized in 2000, have now been removed because some test
results in several years exceeded 0.3%; ‘Finola’ and ‘Uniko B’ are under
probation because of elevated levels), but on the whole most of the permitted
cultivars have maintained highly consistent development of quite low levels of
THC.
Hemp seeds contain virtually no THC, but THC contamination results from
contact of the seeds with the resin secreted by the epidermal glands on the
leaves and floral parts, and also by the failure to sift away all of the bracts
(which have the highest concentration of THC of any parts of the plant) that
cover the seeds. This results in small levels of THC appearing in hempseed oil
and foods made with the seeds. Although most of the western hemp-growing world
uses 0.3% THC as a maximum concentration for authorized cultivation of hemp
plants, regulations in various countries allow only a much lower level of THC in
human food products manufactured from the seeds. Currently, up to 10 ppm THC is
permitted in seeds and oil products used for food purposes in Canada. In
Germany, more stringent limits were set for food in 2000: 5 ppm in food oil,
0.005 ppm in beverages, and 0.15 ppm in all other foods. The US Drug Enforcement
Administration published new regulations on hemp in the Federal Register on
October 9th 2001 that in effect 4 months later would ban the food use of hemp in
the US because any amount of THC would be unacceptable in foods (follow links at
www.hempreport.com/). These proposals are currently being challenged by the hemp
industry. Limits have been set because of concerns about possible toxicity and
interference with drug tests (Grotenhermen et al. 1998). An extensive analysis
of literature dealing with the toxicity of hemp is in Orr and Starodub (1999;
see Geiwitz 2001 for an analysis). Because hemp food products are considered to
have great economic potential, there is considerable pressure on the hemp
industry in North America to reduce THC levels.
The Drug Enforcement Agency and the Office of National Drug Control Policy of
the US raised concerns over tests conducted from 1995 to 1997 that showed that
consumption of hempseed products available during that period led to
interference with drug-testing programs for marijuana use. Federal US programs
utilize a THC metabolite level of 50 parts per billion in urine. Leson (2000)
found that this level was not exceeded by consuming hemp products, provided that
THC levels are maintained below 5 ppm in hemp oil, and below 2 ppm in hulled
seeds. Nevertheless the presence of even minute trace amounts of THC in foods
remains a tool that can be used by those wishing to prevent the hemp oilseed
industry from developing.
FIBER USES
Based on world production of fibers in 1999, about 54.5% was synthetic (of
which 60.3% was polyester), 42.9% was plant fiber (of which 78.5% was cotton),
and 2.6% was wool (Karus 2000). In addition to cotton, flax is the only other
significant plant fiber crop grown in temperate regions of the world (kenaf has
received some enthusiastic backing in the southern US in recent years, but is
most cheaply produced in India, Bangladesh, and China). Flax held 2.7% of the
world plant fiber market in 1999, while hemp had only 0.3% (Karus 2000). Hemp
fiber can potentially replace other biological fibers in many applications, but
also, as noted below, can sometimes compete with minerals such as glass fiber
and steel. As forests diminish, cultivation of annual plants as fiber sources is
likely to increase. While crop residues like cereal straw will probably supply
much of the need, specialty fiber plants such as hemp also have potential. The
four conditions that will need to be met are (after Bolton 1995): (1) the
material should be produced at a large enough scale; (2) the price should be low
enough; (3) the fiber characteristics should be adequate for the end use; and
(4) proven technology should be available for the processing of the new raw
material. Of these criteria only point 3 is adequately met at this time for hemp
in North America, but this is to be expected in a crop that has only begun to be
cultivated after an absence of many years.
One of the reasons hemp fiber has been valued is because of its length. The
primary bast fibers in the bark are 5–40 mm long, and are amalgamated in fiber
bundles which can be 1–5 m long (secondary bast fibers are about 2 mm long). The
woody core fibers are short—about 0.55 mm—and like hardwood fibers are cemented
together with considerable lignin. The core fibers are generally considered too
short for high grade paper applications (a length of 3 mm is considered ideal),
and too much lignin is present. While the long bast fibers have been used to
make paper almost for 2 millennia, the woody core fibers have rarely been so
used. Nevertheless it has been suggested that the core fibers could be used for
paper making, providing appropriate technology was developed (de Groot et al.
1998). In any event, the core fibers, have found a variety of uses, as detailed
below. The long, lignin-poor bast fibers also have considerable potential to be
used in many non-paper, non-textile applications, as noted below.
Selection for fiber has resulted in strains that have much more bark fiber
tissues and much less woody core than encountered in narcotic strains, oilseed
strains, and wild plants (Fig. 12). In non-fiber strains of
Cannabis,
bark can be less than one quarter of the stem tissues (i.e. more than three
quarters can be woody core). By contrast, in fiber strains half of the stem
tissues can be bark, and more than half of this can be the desirable long
primary fibers (de Meijer 1995). Non-fiber strains rarely have as much as 15%
fiber in the bark.
Fig. 12. Cross sections of stems at internodes of a fiber plant (left)
and of a narcotic plant (right). Fiber cultivars have stems that are more hollow
at the internodes, i.e. less wood, since this allows more energy to be directed
into the production of bark fiber.
Other desirable features of hemp fibers are strength and durability
(particularly resistance to decay), which made hemp useful in the past for rope,
nets, sail-cloth, and oakum for caulking. During the age of sailing ships,
Cannabis was considered to provide the very best of canvas, and indeed
this word is derived from
Cannabis. Several factors combined to decrease
the popularity of hemp in the late 19th and early 20th centuries. Increasing
limitation of cheap labor for traditional production in Europe and the New World
led to the creation of some mechanical inventions, but too late to counter
growing interest in competitive crops. Development of other natural fibers as
well as synthetic fibers increased competition for hemp’s uses as a textile
fiber and for cordage. Hemp rag had been much used for paper, but the 19th
century introduction of the chemical woodpulping process considerably lowered
demand for hemp. The demise of the sail diminished the market for canvas.
Increasing use of the plant for drugs gave hemp a bad image. All this led to the
discontinuation of hemp cultivation in the early and middle parts of the 20th
century in much of the world where cheap labor was limited. In the 19th century
softer fabrics took over the clothing market, and today, hemp constitutes only
about 1% of the natural fiber market. At least some production of hemp for fiber
still occurs in Russia, China, the Ukraine, Poland, Hungary, the countries of
the former Yugoslavia, Romania, Korea, Chile, and Peru. There has been renewed
interest in England, Australia, and South Africa in cultivating fiber hemp.
Italy has an outstanding reputation for high-quality hemp, but productivity has
waned for the last several decades. In France, a market for high-quality paper,
ironically largely cigarette paper, has developed (such paper is completely free
of the intoxicating resin). Modern plant breeding in Europe has produced several
dozen hemp strains, although by comparison with other fiber crops there are
relatively few described varieties of hemp. Since World War II, breeding has
been concerned most particularly with the development of monoecious varieties.
Gehl (1995) reviewed fiber hemp development in Canada in the early 20th century,
and concluded that the prospects for a traditional fiber industry were poor.
However, as outlined below, there are now many non-traditional usages for hemp
fiber which require consideration. Hemp long fiber is one of the strongest and
most durable of natural fibers, with high tensile strength, wet strength, and
other characteristics that make it technically suited for various industrial
products (Karus and Leson 1996).
From 1982 to 2002 the EU provided the equivalent of about 50 million dollars
to develop new flax and hemp harvesting and fiber processing technologies (Karus
et al. 2000). Because of the similarities of flax and hemp, the technologies
developed for one usually are adaptable to the other. In addition, various
European nations and private firms contributed to the development of hemp
technologies. Accordingly, Europe is far more advanced in hemp development with
respect to all fiber-based applications than other parts of the world. The EU
currently dedicates about 30,000 ha to hemp production. France is the leading
country in hemp cultivation in the EU, and 95% of the non-seed production is
used for “specialty pulp” as described below. Harvesting and processing
machinery for fiber hemp is highly advanced in Europe, and some has been
imported into Canada. However, there is insufficient fiber processing capacity
to handle hemp produced in Canada.
Textiles
Hemp is a bast fiber crop, i.e. the most desirable (“long”) fibers are found
in the phloem-associated tissues external to the phloem, just under the “bark.”
The traditional and still major first step in fiber extraction is to ret (“rot”)
away the softer parts of the plant, by exposing the cut stems to microbial decay
in the field (“dew retting,” shown in Figs. 46 and 47) or submerged in water
(“water retting, ” shown in Fig. 13). The result is to slough off the outer
parts of the stem and to loosen the inner woody core (the “hurds”) from the
phloem fibers (Fig. 14). Water retting has been largely abandoned in countries
where labor is expensive or environmental regulations exist. Water retting,
typically by soaking the stalks in ditches, can lead to a high level of
pollution. Most hemp fiber used in textiles today is water retted in China and
Hungary. Retting in tanks rather than in open bodies of water is a way of
controlling the effluents while taking advantage of the high-quality fiber that
is produced. Unlike flax, hemp long fiber requires water retting for preparation
of high-quality spinnable fibers for production of fine textiles. Improved
microorganisms or enzymes could augment or replace traditional water retting.
Steam explosion is another potential technology that has been experimentally
applied to hemp (Garcia-Jaldon et al. 1998). Decorticated material (i.e.
separated at least into crude fiber) is the raw material, and this is subjected
to steam under pressure and increased temperature which “explodes” (separates)
the fibers so that one has a more refined (thinner) hemp fiber that currently is
only available from water retting. Even when one has suitably separated long
fiber, specialized harvesting, processing, spinning and weaving equipment are
required for preparing fine hemp textiles. The refinement of equipment and new
technologies are viewed as offering the possibility of making fine textile
production practical in western Europe and North America, but at present China
controls this market, and probably will remain dominant for the foreseeable
future.
 |
 |
| Fig. 13. Water retting of hemp in Yugoslavia. (Courtesy of Dr. J.
Berenji, Institute of Field and Vegetable Crops, Novi Sad.) |
Fig. 14. Fiber in retted hemp stem. This stem was bent sharply after
retting, breaking the woody central portion (hurds), leaving the bark fibers
unbroken. The two portions of stem are separated in this photograph, and are
joined by the tough bark fibers. |
There are practical, if cruder alternatives to separate the long fiber for
high-quality textile production, but in fact such techniques are used mostly for
non-textile applications. This involves production of “whole fibers” (i.e.
harvesting both the long fibers from the cortex and the shorter fibers from
throughout the stem), and technologies that utilize shortened hemp fibers. This
approach is currently dominant in western Europe and Canada, and commences with
field dew retting (typically 2–3 weeks). A principal limitation is climatic—the
local environment should be suitably but not excessively moist at the close of
the harvest season. Once stalks are retted, dried, and baled, they are processed
to extract the fiber. In traditional hemp processing, the long fiber was
separated from the internal woody hurds in two steps, breaking (stalks were
crushed under rollers that broke the woody core into short pieces, some of which
were separated) and scutching (the remaining hurds, short fibers (“tow”) and
long fibers (“line fiber, ” “long-line fiber”) were separated). A single,
relatively expensive machine called a decorticator can do these two steps as
one. In general in the EU and Canada, fibers are not separated into tow and line
fibers, but are left as “whole fiber.” In western Europe, the fiber is often
“cottonized,” i.e. chopped into short segments the size of cotton and flax
fiber, so that the fibers can be processed on flax processing machinery, which
is very much better developed than such machinery is for hemp. In North America
the use of hemp for production of even crude textiles is marginal. Accordingly,
the chief current fiber usages of North American, indeed of European hemp, are
non-textile.
Although always sold at a premium price, hemp clothing has a natural appeal
to a sector of the population. Hemp clothes are resistant to abrasion, but are
typically abrasive. However, appropriate processing and blending with other
natural fibers has significantly improved the “feel” of the product, and in
China hemp textiles indistinguishable from fine linens in texture are available.
Weaving of hemp fibers into textiles and apparel is primarily done in China,
Hungary, Romania, Russia, and the Ukraine. Processing costs are higher for
industrial hemp because the fibers vary from the standard specifications for
fiber length and diameter established for the equipment used in most textile and
apparel factories, necessitating the use of specialty machines. The North
American hemp apparel industry today is based on fiber, yarn, and fabrics
imported from Eastern Europe and China. The extraction technology and spinning
facilities, to say nothing of much lower labor costs, make it very difficult for
the potential development of a hemp textile industry in North America. The fact
that spinning facilities for natural fibers are so concentrated in China is
making it increasingly difficult to competitively produce hemp fabrics
elsewhere. This of course lessens the value-added future of growing hemp for a
potential textile industry in North America. It is possible, however, that new
technologies could change this situation, and especially in the EU development
is underway to establish a fledgling domestic hemp textile industry. In addition
to textiles used in clothing, coarser woven cloth (canvas) is used for
upholstery, bags, sacks, and tarpaulins. There is very little effort in North
America to produce such woven products, and non-woven material (Fig. 15) can be
more easily produced. Hempline in Ontario, the first firm to grow hemp for
commercial purposes in North America since the second word war (starting with
experimental cultivation in 1994), is the exception, and is concerned with
production of fiber for upholstery and carpeting.
Fig. 15. Multi-purpose matting, fabricated from hemp. (Courtesy of
Kenex Ltd., Pain Court, Ontario.)
Pulp and Paper
Van Roekel (1994) has pointed out that Egyptian papyrus sheets are not
“paper,” because the fiber strands are woven, not “wet-laid;” the oldest
surviving paper is over 2,000 years of age, from China, and was made from hemp
fiber (Fleming and Clarke 1998). Until the early 19th century, hemp, and flax
were the chief paper-making materials. In historical times, hemp rag was
processed into paper. Using hemp directly for paper was considered too
expensive, and in any event the demand for paper was far more limited than
today. Wood-based paper came into use when mechanical and chemical pulping was
developed in the mid 1800s in Germany and England. Today, at least 95% of paper
is made from wood pulp.
The pulp and paper industry based on wood has considered the use of hemp for
pulp, but only on an experimental basis. Hemp’s long fibers could make paper
more recyclable. Since virgin pulp is required for added strength in the
recycling of paper, hemp pulp would allow for at least twice as many cycles as
wood pulp. However, various analyses have concluded that the use of hemp for
conventional paper pulp is not profitable (Fertig 1996).
“Specialty pulp” is the most important component of the hemp industry of the
EU, and is expected to remain its core market for the foreseeable future. The
most important specialty pulp products made from hemp are cigarette paper (Fig.
16), bank notes, technical filters, and hygiene products. Other uses include art
papers and tea bags. Several of these applications take advantage of hemp’s high
tear and wet strength. This is considered to be a highly stable, high-priced
niche market in Europe, where hemp has an 87% market share of the “specialty
pulp” sector (Karus et al. 2000). In Europe, decortication/refining machines are
available that can produce 10 t/hour of hemp fiber suitable for such pulp use.
North American capacity for hemp pulp production and value-added processing is
much more limited than that of Europe, and this industry is negligible in North
America.
Fig. 16. Hemp cigarette paper, the most profitable paper product
currently manufactured from hemp.
Hemp paper is useful for specialty applications such as currency and
cigarette papers where strength is needed. The bast fiber is of greatest
interest to the pulp and paper industry because of its superior strength
properties compared to wood. However, the short, bulky fibers found in the inner
part of the plant (hurds) can also be used to make cheaper grades of paper,
apparently without greatly affecting quality of the printing surface. Hemp is
not competitive for newsprint, books, writing papers, and general paper (grocery
bags, coffee cups, napkins), although there is a specialty or novelty market for
those specifically wishing to support the hemp industry by purchasing hemp
writing or printing paper despite the premium price (Fig. 17).
Fig. 17. Hemp paper products (writing paper, notebook, envelopes).
A chief argument that has been advanced in favor of developing hemp as a
paper and pulp source has been that as a non-wood or tree-free fiber source, it
can reduce harvesting of primary forests and the threat to associated
biodiversity. It has been claimed that hemp produces three to four times as much
useable fiber per hectare per annum as forests. However, Wong (1998) notes
evidence that in the southern US hemp would produce only twice as much pulp as
does a pine plantation (but see discussion below on suitability of hemp as a
potential lumber substitute in areas lacking trees).
Hemp paper is high-priced for several reasons. Economies of scale are such
that the supply of hemp is minute compared to the supply of wood fiber. Hemp
processing requires non-wood-based processing facilities. Hemp paper is
typically made only from bast fibers, which require separation from the hurds,
thereby increasing costs. This represents less than 50% of the possible fiber
yield of the plant, and future technologies that pulp the whole stalks could
decrease costs substantially. Hemp is harvested once a year, so that it needs to
be stored to feed mills throughout the year. Hemp stalks are very bulky,
requiring much handling and storage. Transportation costs are also very much
higher for hemp stalks than for wood chips. Waste straw is widely available from
cereals and other crops, and although generally not nearly as desirable as hemp,
can produce bulk pulp far more cheaply than can be made from hemp. In addition
to agricultural wastes, there are vast quantities of scrub trees, especially
poplar, in northern areas, that can supply large amounts of low-quality wood
fiber extremely cheaply. Moreover, in northern areas fast-growing poplars and
willows can be grown, and such agro-forestry can be very productive and
environmentally benign. And, directly or indirectly, the lumber/paper industry
receives subsidies and/or supports, which is most unlikely for hemp.
Plastic Composites for the Automobile and Other Manufacturing Sectors
With respect to fiber, a “composite” is often defined as a material
consisting of 30%–70% fiber and 70%–30% matrix (Bolton 1995). However, in North
America particleboards and fiberboards, which generally contain less than 10%
adhesive or matrix, are sometimes referred to as composites. This section
addresses plastic-type composites. In plastics, fibers are introduced to improve
physical properties such as stiffness, impact resistance, bending and tensile
strength. Man-made fibers of glass, kevlar and carbon are most commonly used
today, but plant fibers offer considerable cost savings along with comparable
strength properties.
Plastic composites for automobiles are the second most important component of
the hemp industry of the EU. Natural fibers in automobile composites are used
primarily in press-molded parts (Fig. 18). There are two widespread
technologies. In thermoplastic production, natural fibers are blended with
polypropylene fibers and formed into a mat, which is pressed under heat into the
desired form. In thermoset production the natural fibers are soaked with binders
such as epoxy resin or polyurethane, placed in the desired form, and allowed to
harden through polymerization. Hemp has also been used in other types of
thermoplastic applications, including injection molding. The characteristics of
hemp fibers have proven to be superior for production of molded composites. In
European manufacturing of cars, natural fibers are used to reinforce door
panels, passenger rear decks, trunk linings, and pillars. In 1999 over 20,000 t
of natural fiber were used for these purposes in Europe, including about, 2,000
t of hemp. It has been estimated that 5–10 kg of natural fibers can be used in
the molded portions of an average automobile (excluding upholstery). The demand
for automobile applications of hemp is expected to increase considerably,
depending on the development of new technologies (Karus et al. 2000).
Fig. 18. C-class Mercedes-Benz automobiles have more than 30 parts
made of natural fibers, including hemp. (Courtesy of T. Schloesser,
Daimler-Chrysler.)
Henry Ford recognized the utility of hemp in early times. In advance of
today’s automobile manufacturers, he constructed a car with certain components
made of resin stiffened with hemp fiber (Fig. 19). Rather ironically in view of
today’s parallel situation, Henry Ford’s hemp innovations in the 1920s occurred
at a time of crisis for American farms, later to intensify with the depression.
The need to produce new industrial markets for farm products led to a broad
movement for scientific research in agriculture that came to be labeled “Farm
Chemurgy,” that today is embodied in chemical applications of crop
constituents.
Fig. 19. Henry Ford swinging an axe at his 1941 car to demonstrate the
toughness of the plastic trunk door made of soybean and hemp. (From the
collections of Henry Ford Museum & Greenfield Village.)
There is also considerable potential for other industries using hemp in the
manner that the automobile industry has demonstrated is feasible. Of course, all
other types of transportation vehicles from bicycles to airplanes might make use
of such technology. Natural fibers have considerable advantages for use in
conveyance (Karus et al. 2000): low density and weight reduction, favorable
mechanical, acoustical, and processing properties (including low wear on tools),
no splintering in accidents, occupational health benefits (compared to glass
fibers), no off-gassing of toxic compounds, and price advantages. Additional
types of composite using hemp in combination with other natural fibers,
post-industrial plastics or other types of resins, are being used to produce
non-woven matting for padding, sound insulation, and other applications.
Building Construction Products
Thermal Insulation. Thermal insulation products (Fig. 20, 21) are the
third most important sector of the hemp industry of the EU. These are in very
high demand because of the alarmingly high costs of heating fuels, ecological
concerns about conservation of non-renewable resources, and political-strategic
concerns about dependence on current sources of oil. This is a market that is
growing very fast, and hemp insulation products are increasing in popularity. In
Europe, it has been predicted that tens of thousands of tonnes will be sold by
2005, shared between hemp and flax (Karus et al. 2000).
 |
 |
| Fig. 20. Spun, loosely compacted hemp insulation. (Manufactured by La
Chanvrière de l’Aube, France.) |
Fig. 21. Loose Isochanvre® thermal insulation being placed between
joists. (Courtesy of M. Périer, Chènovotte Habitat,
France.) |
Fiberboard. In North America the use of nonwood fibers in sheet fiberboard
(“pressboard” or “composite board”) products is relatively undeveloped. Flax,
jute, kenaf, hemp, and wheat straw can be used to make composite board. Wheat
straw is the dominant nonwood fiber in such applications. Although it might seem
that hemp bast fibers are desirable in composite wood products because of their
length and strength, in fact the short fibers of the hurds have been found to
produce a superior product (K. Domier, pers. commun.). Experimental production
of hemp fiberboard has produced extremely strong material (Fig. 22). The
economic viability of such remains to be tested. Molded fiberboard products are
commercially viable in Europe (Fig. 23), but their potential in North America
remains to be determined.
 |
 |
| Fig. 22. Experimental fiberboard made with hemp. (Courtesy Dr. K.
Domier, Univ. Alberta, Edmonton.) |
Fig. 23. Molded fiberboard products. (Courtesy of HempFlax, Oude
Pekela, The Netherlands). |
Cement (Concrete) and Plaster. Utilizing the ancient technique of
reinforcing clay with straw to produce reinforced bricks for constructing
domiciles, plant fibers have found a number of comparable uses in modern times.
Hemp fibers added to concrete increase tensile strength while reducing shrinkage
and cracking. Whole houses have been made based on hemp fiber (Fig. 24, 25). In
North America, such usage has only reached the level of a cottage industry.
Fiber-reinforced cement boards and fiber-reinforced plaster are other
occasionally produced experimental products. Hemp fibers are produced at much
more cost than wood chips and straw from many other crops, so high-end
applications requiring high strength seem most appropriate.
 |
 |
| Fig. 24. New building in France being constructed entirely
of hemp. Wall castings are a conglomerate of Isochanvre® lime-hemp, for
production of a 200 mm thick monolithic wall without an interior wall lining.
(Courtesy of M. Périer, Chènovotte Habitat, France.) |
Fig. 25. The “hemp house” under construction on the Oglala
Lakota Nation (Pine Ridge Reservation), South Dakota. Foundation blocks for the
house are made with hemp fiber as a binder in cement. Stucco is also of hemp.
Shingles are 60% hemp in a synthetic polymer. Hemp insulation is used
throughout. (Courtesy of Oglala Sioux Tribe, Slim Butte Land Use Association,
and S. Sauser.) |
The above uses are based on hemp as a mechanical strengthener of materials.
Hemp can also be chemically combined with materials. For example, hemp with
gypsum and binding agents may produce light panels that might compete with
drywall. Hemp and lime mixtures make a high quality plaster. Hemp hurds are rich
in silica (which occurs naturally in sand and flint), and the hurds mixed with
lime undergo mineralization, to produce a stone-like material. The technology is
most advanced in France (Fig. 26). The mineralized material can be blown or
poured into the cavities of walls and in attics as insulation. The foundations,
walls, floors, and ceilings of houses have been made using hemp hurds mixed with
natural lime and water. Sometimes plaster of Paris (pure gypsum), cement, or
sand is added. The resulting material can be poured like concrete, but has a
texture vaguely reminiscent of cork—much lighter than cement, and with better
heat and sound-insulating properties. An experimental “ceramic tile” made of
hemp has recently been produced (Fig. 27).
 |
 |
| Fig. 26. Renovation of plaster walls of a traditional
timber frame 16th century house (Mansion Raoul de la Faye, Paris) with
Isochanvre® lime-hemp conglomerate. (Courtesy of M. Périer, Chènovotte Habitat,
France.) |
Fig. 27. Hemp “ceramic tile.” (Courtesy of Kenex Ltd., Pain
Court, Ontario.) |
Animal Bedding
The woody core (hurds, sometimes called shives) of hemp makes remarkably good
animal bedding (Fig. 28, 29). The hurds are sometimes molded into small pellets
for bedding applications (Fig. 30). Such appears to be unsurpassed for horse
bedding, and also make an excellent litter for cats and other pets (Fig. 31).
The hurds can absorb up to five times their weight in moisture (typically 50%
higher than wood shavings), do not produce dust (following initial dust
removal), and are easily composted. Hemp bedding is especially suited to horses
allergic to straw. In Europe, the animal bedding market is not considered
important (Karus et al. 2000), but in North America there are insufficient hemp
hurds available to meet market demand.
 |
 |
| Fig. 28. Commercial warehouse of baled hemp animal bedding.
(Courtesy of Kenex Ltd., Pain Court, Ontario.) |
Fig. 29. Animal bedding made from hemp hurds. |
 |
 |
| Fig. 30. Pelleted hemp hurds. (Courtesy of La Chanvrière de
l’Aube, Bar sur Aube, France.) |
Fig. 31. Songbirds on hemp litter. (Courtesy of La
Chanvrière de l’Aube, Bar sur Aube, France.) |
The high absorbency of hemp hurds has led to their occasional use as an
absorbent for oil and waste spill cleanup. Hemp as an industrial absorbent has
generated some interest in Alberta, for use in land reclamation in the oil and
gas industry. Because hemp hurds are a costly product, it is likely that animal
bedding will remain the most important application.
Geotextiles
“Geotextiles” or “agricultural textiles” include (1) ground-retaining,
biodegradable matting designed to prevent soil erosion, especially to stabilize
new plantings while they develop root systems along steep highway banks to
prevent soil slippage (Fig. 32); and (2) ground-covers designed to reduce weeds
in planting beds (in the manner of plastic mulch). At present the main materials
used are polymeric (polythene, spun-blown polypropylene) and some glass fiber
and natural fibers. Both woven and non-woven fibers can be applied to
geotextiles; woven and knitted materials are stronger and the open structure may
be advantageous (e.g. in allowing plants to grow through), but non-wovens are
cheaper and better at suppressing weeds. Flax and hemp fibers exposed to water
and soil have been claimed to disintegrate rapidly over the course of a few
months, which would make them unacceptable for products that need to have
long-term stability when exposed to water and oil. Coco (coir) fiber has been
said to be much more suitable, due to higher lignin content (40%–50%, compared
to 2%–5% in bast fibers); these are much cheaper than flax and hemp fibers
(Karus et al. 2000). However, this analysis does not do justice to the
developing hemp geotextile market. Production of hemp erosion control mats is
continuing in both Europe and Canada. Given the reputation for rot resistance of
hemp canvas and rope, it seems probable that ground matting is a legitimate use.
Moreover, the ability to last outdoors for many years is frequently undesirable
in geotextiles. For example, the widespread current use of plastic netting to
reinforce grass sod is quite objectionable, the plastic persisting for many
years and interfering with lawn care. Related to geotextile applications is the
possibility of using hemp fiber as a planting substrate (biodegradable pots and
blocks for plants), and as biodegradable twine to replace plastic ties used to
attach plants to supporting poles. Still another consideration is the “green
ideal” of producing locally for local needs; by this credo, hemp is preferable
in temperate regions to the use of tropical fibers, which need to be
imported.
Fig. 32. Hemp-based erosion control blanket. Top left: Close-up of
100% hemp fiber blanket. Top right: Grass growing through blanket. Bottom:
Demonstration of installation of blanket, near La Rivière, Manitoba. (Courtesy
of Mark Myrowich, ErosionControlBlanket.com)
OILSEED USES
The cultivation of hemp in the EU is heavily weighted toward fiber production
over oilseed production. In 1999, the EU produced about 27,000 t of hemp fiber,
but only about 6,200 t of hemp seeds, mostly in France, and 90% of this was used
as animal feed (Karus et al. 2000). The seeds (Fig. 33) have traditionally been
employed as bird and poultry feed, but feeding the entire seeds to livestock has
been considered to be a poor investment because of the high cost involved
(although subsidization in Europe allows such usage, especially in France where
hemp seeds are not legally permitted in human food). As pointed out later,
higher yield and better harvesting practices may make whole hempseed an
economical livestock feed. Moreover, seed cake left after expressing the oil is
an excellent feed. Efforts are underway in Europe to add value in the form of
processed products for hemp, especially cosmetics and food but, as noted below,
the North American market is already quite advanced in oilseed applications.
Fig. 33. “Seeds” (achenes) of hemp, with a match for scale.
In the EU and Canada, hemp has often been grown as a dual-purpose crop, i.e.
for both fiber and oilseed. In France, dual purpose hemp is typically harvested
twice—initially the upper seed-bearing part of the stems is cut and threshed
with a combine, and subsequently the remaining stems are harvested. Growing hemp
to the stage that mature seeds are present compromises the quality of the fiber,
because of lignification. As well, the hurds become more difficult to separate.
The lower quality fiber, however, is quite utilizable for pulp and non-woven
usages.
In North America, oilseed hemp has several advantages over fiber hemp. Hemp
seed and oil can fetch higher prices than hemp fiber. Hemp seed can be processed
using existing equipment, while processing of hemp fiber usually requires new
facilities and equipment.
Canada is specialized on oilseed production and processing, so that hemp oil
and grain are much more suitable than fiber. Because of the extensive
development of oilseeds in Canada, there is extensive capacity to produce
high-quality cold-pressed hemp oil. Canada in the last 5 years has made great
advances in the growing, harvesting, and processing of hempseed, and indeed has
moved ahead of the EU in the development of raw materials and products for the
natural foods, nutraceuticals, and cosmetics industries. In the EU, a yield of 1
t/ha is considered good. In Canada, extraordinary yields of 1.5 t/ha have been
realized, at least locally, although in the initial years of hempseed
development in Canada yields were often less than 500 kg/ha. In 1999, the year
of largest Canadian hemp acreage, yields averaged 900 kg/ha. (Ideally, hemp seed
yield should be based on air dry weight—with about 12% moisture. Hemp yields are
sometime uncertain, and could be exaggerated by as much as 50% when moist
weights are reported.)
Canadian experience with growing hemp commercially for the last 4 years has
convinced many growers that it is better to use a single-purpose cultivar, seed
or fiber, than a dual-purpose cultivar. The recent focus of Canadian hemp
breeders has been to develop cultivars with high seed yields, low stature (to
avoid channeling the plants’ energy into stalk, as is the case in fiber
cultivars), early maturation (for the short growing seasons of Canada), and
desirable fatty acid spectrum (especially gamma-linolenic acid).
Food
Dehulled (i.e. hulled) hemp seed is a very recent phenomenon, first produced
in quantity in Europe. Hemp seeds have been used as food since ancient times,
but generally the whole seed, including the hull, was eaten. Hemp seed was a
grain used in ancient China, although there has been only minor direct use of
hemp seed as food by humans. In the past, hemp seed has generally been a food of
the lower classes, or a famine food. Peanut-butter type preparations have been
produced from hemp seed in Europe for centuries, but were rather gritty since
technology for removing the hulls was rudimentary. Modern seed dehulling using
mechanical separation produces a smooth, white, gritless hemp seed meal that
needs no additional treatment before it is consumed. It is important to
understand, therefore, that the quality of modern hemp seed for human
consumption far exceeds anything produced historically. This seed meal should be
distinguished from the protein-rich, oil-poor seed cake remaining after oil has
been expressed, that is used for livestock feed. The seed cake is also referred
to as “seed meal,” and has proven to be excellent for animals (Mustafa et al.
1999).
Hemp seeds have an attractive nutty taste, and are now incorporated into many
food preparations (Fig. 34), often mimicking familiar foods. Those sold in North
America include nutritional (granola-type) or snack bars, “nut butters” and
other spreads, bread, pretzels, cookies, yogurts, pancakes, porridge, fruit
crumble, frozen dessert (“ice cream”), pasta, burgers, pizza, salt substitute,
salad dressings, mayonnaise, “cheese,” and beverages (“milk,” “lemonade,”
“beer,” “wine,” “coffee nog”). Hemp seed is often found canned or vacuum-packed
(Fig. 35). Alcoholic beverages made with hemp utilize hempseed as a flavorant.
Hemp food products currently have a niche market, based particularly on natural
food and specialty food outlets.
 |
 |
| Fig. 34. Some North American food products made with hemp
seed and/or hemp seed oil. |
Fig. 35. Canned hulled hemp seed. (Courtesy of Kenex Ltd.,
Pain Court, Ontario.) |
Edible Oil
The use of
Cannabis for seed oil (Fig. 36) began at least 3 millennia
ago. Hempseed oil is a drying oil, formerly used in paints and varnishes and in
the manufacture of soap. Present cultivation of oilseed hemp is not competitive
with linseed for production of oil for manufacturing, or to sunflower and canola
for edible vegetable oil. However, as noted below, there are remarkable dietary
advantages to hempseed oil, which accordingly has good potential for penetrating
the salad oil market, and for use in a very wide variety of food products. There
is also good potential for hemp oil in cosmetics and skin-care products.
Fig. 36. Hemp oil. (Courtesy of La Chanvrière de l’Aube, Bar sur Aube,
France.)
Foreign sources, China in particular, can produce hemp seed cheaply, but
imported seed must be sterilized, and the delays this usually requires are
detrimental. Seed that has been sterilized tends to go rancid quickly, and so it
is imperative that fresh seed be available, a great advantage for domestic
production. An additional extremely significant advantage that domestic
producers have over foreign sources is organic production, which is important
for the image desired by the hemp food market. Organic certification is much
more reliable in North America than in the foreign countries that offer cheap
seeds. Whereas China used to supply most of the hempseed used for food in North
America, Canadian-grown seeds have taken over this market.
About half of the world market for hemp oil is currently used for food and
food supplements (de Guzman 2001). For edible purposes, hempseed oil is
extracted by cold pressing. Quality is improved by using only the first
pressing, and minimizing the number of green seeds present. The oil varies in
color from off-yellow to dark green. The taste is pleasantly nutty, sometimes
with a touch of bitterness. Hemp oil is high in unsaturated fatty acids (of the
order of 75%), which can easily oxidize, so it is unsuitable for frying or
baking. The high degree of unsaturation is responsible for the extreme
sensitivity to oxidative rancidity. The oil has a relatively short shelf life.
It should be extracted under nitrogen (to prevent oxidation), protected from
light by being kept in dark bottles, and from heat by refrigeration. Addition of
anti-oxidants prolongs the longevity of the oil. Steam sterilization of the
seeds, often required by law, allows air to penetrate and so stimulates
rancidity. Accordingly, sterilized or roasted hemp seeds, and products made from
hemp seed that have been subjected to cooking, should be fresh. The value of
hemp oil from the point of view of the primary components is discussed below. In
addition, it has been suggested that other components, including trace amounts
of terpenes and cannabinoids, could have health benefits (Leizer et al. 2000).
According to an ancient legend (Abel 1980), Buddha, the founder of Buddhism,
survived a 6-year interval of asceticism by eating nothing but one hemp seed
daily. This apocryphal story holds a germ of truth—hemp seed is astonishingly
nutritional.
Fatty Acids. The quality of an oil or fat is most importantly
determined by its fatty acid composition. Hemp is of high nutritional quality
because it contains high amounts of unsaturated fatty acids, mostly oleic acid
(C18:1, 10%–16%), linoleic acid (C18:2, 50%–60%), alpha-linolenic acid (C18:3,
20%–25%), and gamma-linolenic acid (C18:3, 2%–5%) (Fig. 37). Linoleic acid and
alpha-linolenic acid are the only two fatty acids that must be ingested and are
considered essential to human health (Callaway 1998). In contrast to
shorter-chain and more saturated fatty acids, these essential fatty acids do not
serve as energy sources, but as raw materials for cell structure and as
precursors for biosynthesis for many of the body’s regulatory biochemicals. The
essential fatty acids are available in other oils, particularly fish and
flaxseed, but these tend to have unpleasant flavors compared to the mellow,
slightly nutty flavor of hempseed oil. While the value of unsaturated fats is
generally appreciated, it is much less well known that the North American diet
is serious nutritionally unbalanced by an excess of linoleic over
alpha-linonenic acid. In hempseed, linoleic and alpha-linolenic occur in a ratio
of about 3:1, considered optimal in healthy human adipose tissue, and apparently
unique among common plant oils (Deferne and Pate 1996). Gamma-linolenic acid or
GLA is another significant component of hemp oil (1%–6%, depending on cultivar).
GLA is a widely consumed supplement known to affect vital metabolic roles in
humans, ranging from control of inflammation and vascular tone to initiation of
contractions during childbirth. GLA has been found to alleviate psoriasis,
atopic eczema, and mastalgia, and may also benefit cardiovascular, psychiatric,
and immunological disorders. Ageing and pathology (diabetes, hypertension, etc.)
may impair GLA metabolism, making supplementation desirable. As much as 15% of
the human population may benefit from addition of GLA to their diet. At present,
GLA is available in health food shops and pharmacies primarily as soft gelatin
capsules of borage or evening primrose oil, but hemp is almost certainly a much
more economic source. Although the content of GLA in the seeds is lower, hemp is
far easier to cultivate and higher-yielding. It is important to note that hemp
is the only current natural food source of GLA, i.e. not requiring the
consumption of extracted dietary supplements. There are other fatty acids in
small concentrations in hemp seed that have some dietary significance, including
stearidonic acid (Callaway et al. 1996) and eicosenoic acid (Mölleken and
Theimer 1997). Because of the extremely desirable fatty acid constitution of
hemp oil, it is now being marketed as a dietary supplement in capsule form (Fig.
38).
 |
 |
| Fig. 37. Content of principal fatty acids in hempseed oil,
based on means of 62 accessions grown in southern Ontario (reported in Small and
Marcus 2000). |
Fig. 38. Hemp oil in capsule form sold as a dietary
supplement. |
Tocopherols. Tocopherols are major antioxidants in human serum. Alpha-
beta-, gamma- and delta-tocopherol represent the vitamin E group. These
fat-soluble vitamins are essential for human nutrition, especially the
alpha-form, which is commonly called vitamin E. About 80% of the tocopherols of
hempseed oil is the alpha form. The vitamin E content of hempseed is
comparatively high. Antioxidants in hempseed oil are believed to stabilize the
highly polyunsaturated oil, tending to keep it from going rancid. Sterols in the
seeds probably serve the same function, and like the tocopherols are also
desirable from a human health viewpoint.
Protein. Hemp seeds contain 25%–30% protein, with a reasonably
complete amino acid spectrum. About two thirds of hempseed protein is edestin.
All eight amino acids essential in the human diet are present, as well as
others. Although the protein content is smaller than that of soybean, it is much
higher than in grains like wheat, rye, maize, oat, and barley. As noted above,
the oilcake remaining after oil is expressed from the seeds is a very nutritious
feed supplement for livestock, but it can also be used for production of a
high-protein flour.
Personal Care Products
In the 1990s, European firms introduced lines of hemp oil-based personal care
products, including soaps, shampoos, bubble baths, and perfumes. Hemp oil is now
marketed throughout the world in a range of body care products, including
creams, lotions, moisturizers, and lip balms. In Germany, a laundry detergent
manufactured entirely from hemp oil has been marketed. Hemp-based cosmetics and
personal care products account for about half of the world market for hemp oil
(de Guzman 2001).
One of the most significant developments for the North American hemp industry
was investment in hemp products by Anita and Gordon Roddick, founders of The
Body Shop, a well known international chain of hair and body care retailers.
This was a rather courageous and principled move that required overcoming
American legal obstacles related to THC content. The Body Shop now markets an
impressive array of hemp nutraceutical cosmetics (Fig. 39), and this has given
the industry considerable credibility. The Body Shop has reported gross sales of
about a billion dollars annually, and that about 4% of sales in 2000 were hemp
products.
Fig. 39. Body care products offered by the Body Shop. (“Chanvre” is
French for hemp.)
Industrial Fluids
The vegetable oils have been classified by “iodine value” as drying
(120–200), semi-drying (100–120), and non-drying (80–100), which is determined
by the degree of saturation of the fatty acids present (Raie et al. 1995). Good
coating materials prepared from vegetable oil depend on the nature and number of
double bonds present in the fatty acids. Linseed oil, a drying oil, has a very
high percentage of linolenic acid. Hempseed oil has been classified as a
semi-drying oil, like soybean oil, and is therefore more suited to edible than
industrial oil purposes. Nevertheless hemp oil has found applications in the
past in paints, varnishes, sealants, lubricants for machinery, and printing
inks. However, such industrial end uses are not presently feasible as the oil is
considered too expensive (de Guzman 2001). Larger production volumes and lower
prices may be possible, in which case hemp oil may find industrial uses similar
to those of linseed (flax), soybean, and sunflower oils, which are presently
used in paints, inks, solvents, binders, and in polymer plastics. Hemp shows a
remarkable range of variation in oil constituents, and selection for oilseed
cultivars with high content of valued industrial constituents is in
progress.
MEDICINAL MARIJUANA
Marijuana has in fact been grown for medicinal research in North America by
both the Canadian (Fig. 40) and American governments, and this will likely
continue. The possibility of marijuana becoming a legal commercial crop in North
America is, to say the least, unlikely in the foreseeable future. Nevertheless
the private sector is currently producing medicinal marijuana in Europe and
Canada, so the following orientation to marijuana as a potential authorized crop
is not merely academic.
Fig. 40. A truckload of Canadian medicinal marijuana from a plantation
in Ottawa in 1971. More than a ton of marijuana was prepared for experimental
research (described in Small et al. 1975).
The objectivity of scientific evaluation of the medicinal value of marijuana
to date has been questioned. In the words of Hirst et al. (1998): “
The
...status of cannabis has made modern clinical research almost impossible. This
is primarily because of the legal, ethical and bureaucratic difficulties in
conducting trials with patients. Additionally, the general attitude towards
cannabis, in which it is seen only as a drug of abuse and addiction, has not
helped.” In a recent editorial, the respected journal Nature (2001) stated:
“
Governments, including the US federal government, have until recently
refused to sanction the medical use of marijuana, and have also done what they
can to prevent its clinical testing. They have defended their inaction by
claiming that either step would signal to the public a softening of the
so-called ‘war on drugs.’... The pharmacology of cannabinoids is a valid field
of scientific investigation. Pharmacologists have the tools and the
methodologies to realize its considerable potential, provided the political
climate permits them to do so.” Given these current demands for research on
medicinal marijuana, it will be necessary to produce crops of drug types of
C. sativa.
Earliest reference to euphoric use of
C. sativa appears to date to
China of 5 millennia ago, but it was in India over the last millennium that drug
consumption became more firmly entrenched than anywhere else in the world. Not
surprisingly, the most highly domesticated drug strains were selected in India.
While
C. sativa has been used as a euphoriant in India, the Near East,
parts of Africa, and other Old World areas for thousands of years, such use
simply did not develop in temperate countries where hemp was raised. The use of
C. sativa as a recreational inebriant in sophisticated, largely urban
settings is substantially a 20th century phenomenon.
Cannabis drug preparations have been employed medicinally in folk
medicine since antiquity, and were extensively used in western medicine between
the middle of the 19th century and World War II, particularly as a substitute
for opiates (Mikuriya 1969). A bottle of commercial medicinal extract is shown
in Fig. 41. Medical use declined with the introduction of synthetic analgesics
and sedatives, and there is very limited authorized medical use today, but
considerable unauthorized use, including so-called “compassion clubs” dispensing
marijuana to gravely ill people, which has led to a momentous societal and
scientific debate regarding the wisdom of employing cannabis drugs medically,
given the illicit status. There is anecdotal evidence that cannabis drugs are
useful for: alleviating nausea, vomiting, and anorexia following radiation
therapy and chemotherapy; as an appetite stimulant for AIDS patients; for
relieving the tremors of multiple sclerosis and epilepsy; and for pain relief,
glaucoma, asthma, and other ailments [see Mechoulam and Hanus (1997) for an
authoritative medical review, and Pate (1995) for a guide to the medical
literature]. To date, governmental authorities in the US, on the advice of
medical experts, have consistently rejected the authorization of medical use of
marijuana except in a handful of cases. However, in the UK medicinal marijuana
is presently being produced sufficient to supply thousands of patients, and
Canada recently authorized the cultivation of medicinal marijuana for
compassionate dispensation, as well as for a renewed effort at medical
evaluation.
Fig. 41. Medicinal tincture of
Cannabis sativa. (Not legal in
North America.)
Several of the cannabinoids are reputed to have medicinal potential: THC for
glaucoma, spasticity from spinal injury or multiple sclerosis, pain,
inflammation, insomnia, and asthma; CBD for some psychological problems. The
Netherlands firm HortaPharm developed strains of
Cannabis rich in
particular cannabinoids. The British firm G.W. Pharmaceuticals acquired
proprietary access to these for medicinal purposes, and is developing medicinal
marijuana. In the US, NIH (National Institute of Health) has a program of
research into medicinal marijuana, and has supplied a handful of individuals for
years with maintenance samples for medical usage. The American Drug Enforcement
Administration is hostile to the medicinal use of
Cannabis, and for
decades research on medicinal properties of
Cannabis in the US has been
in an extremely inhospitable climate, except for projects and researchers
concerned with curbing drug abuse. Synthetic preparations of THC—dronabinol
(Marinol®) and nabilone (Cesamet®)—are permitted in some cases, but are
expensive and widely considered to be less effective than simply smoking
preparations of marijuana. Relatively little material needs to be cultivated for
medicinal purposes (Small 1971), although security considerations considerably
inflate costs. The potential as a “new crop” for medicinal cannabinoid uses is
therefore limited. However, the added-value potential in the form of proprietary
drug derivatives and drug-delivery systems is huge. The medicinal efficacy of
Cannabis is extremely controversial, and regrettably is often confounded
with the issue of balancing harm and liberty concerning the proscriptions
against recreational use of marijuana. This paper is principally concerned with
the industrial uses of
Cannabis. In this context, the chief significance
of medicinal
Cannabis is that, like the issue of recreational use, it has
made it very difficult to rationally consider the development of industrial hemp
in North America for purposes that everyone should agree are not harmful.
Key analyses of the medicinal use of marijuana are: Le Dain (1972), Health
Council of the Netherlands (1996), American Medical Association (1997), British
Medical Association (1997), National Institutes of Health (1997), World Health
Organization (1997), House of Lords (1998), and Joy et al. (1999).
MINOR USES
Biomass
It has been contended that hemp is notably superior to most crops in terms of
biomass production, but van der Werf (1994b) noted that the annual dry matter
yield of hemp (rarely approaching 20 t/ha) is not exceptional compared to maize,
beet, or potato. Nevertheless, hemp has been rated on a variety of criteria as
one of the best crops available to produce energy in Europe (Biewinga and van
der Bijl 1996). Hemp, especially the hurds, can be burned as is or processed
into charcoal, methanol, methane, or gasoline through pyrolysis (destructive
distillation). As with maize, hemp can also be used to create ethanol. However,
hemp for such biomass purposes is a doubtful venture in North America.
Conversion of hemp biomass into fuel or alcohol is impractical on this
continent, where there are abundant supplies of wood, and energy can be produced
relatively cheaply from a variety of sources. Mallik et al. (1990) studied the
possibility of using hemp for “biogas” (i.e. methane) production, and concluded
that it was unsuitable for this purpose. Pinfold Consulting (1998) concluded
that while there may be some potential for hemp biomass fuel near areas where
hemp is cultivated, “a fuel ethanol industry is not expected to develop based on
hemp.”
Essential Oil
Essential (volatile) oil in hemp is quite different from hempseed oil.
Examples of commercial essential oil product products are shown in Fig. 42. The
essential oil is a mixture of volatile compounds, including monoterpenes,
sesquiterpenes, and other terpenoid-like compounds that are manufactured in the
same epidermal glands in which the resin of
Cannabis is synthesized
(Meier and Mediavilla 1998). Yields are very small—about 10 L/ha (Mediavilla and
Steinemann 1997), so essential oil of
C. sativa is expensive, and today
is simply a novelty. Essential oil of different strains varies considerably in
odor, and this may have economic importance in imparting a scent to cosmetics,
shampoos, soaps, creams, oils, perfumes, and foodstuffs. Switzerland has been a
center for the production of essential oil for the commercial market. Narcotic
strains tend to be more attractive in odor than fiber strains, and because they
produce much higher numbers of flowers than fiber strains, and the (female)
floral parts provide most of the essential oil, narcotic strains are naturally
adapted to essential oil production. Switzerland has permitted strains with
higher THC content to be grown than is allowed in other parts of the world,
giving the country an advantage with respect to the essential oil market.
However, essential oil in the marketplace has often been produced from low-THC
Cannabis, and the THC content of essential oil obtained by steam
distillation can be quite low, producing a product satisfying the needs for very
low THC levels in food and other commercial goods. The composition of extracted
essential oil is quite different from the volatiles released around the fresh
plant (particularly limonene and alpha-pinene), so that a pleasant odor of the
living plant is not necessarily indicative of a pleasant-smelling essential oil.
Essential oil has been produced in Canada by Gen-X Research Inc., Regina. The
world market for hemp essential oil is very limited at present, and probably
also has limited growth potential.
Fig. 42. Bottles of hemp fragrance (left) and essential oil (center),
and pastilles flavored with hemp essential oil (right).
Pesticide and Repellent Potential
McPartland (1997) reviewed research on the pesticide and repellent
applications of
Cannabis. Dried plant parts and extracts of
Cannabis have received rather extensive usage for these purposes in the
past, raising the possibility that research could produce formulations of
commercial value. This possibility is currently hypothetical.
Non-Seed Use of Hemp as Livestock Feed
As noted above, hemp seed cake makes an excellent feed for animals. However,
feeding entire plants is another matter, because the leaves are covered with the
resin-producing glands. While deer, groundhogs, rabbits, and other mammals will
nibble on hemp plants, mammals generally do not choose to eat hemp. Jain and
Arora (1988) fed narcotic
Cannabis refuse to cattle, and found that the
animals “
suffered variable degrees of depression and revealed incoordination
in movement.” By contrast, Letniak et al. (2000) conducted an experimental
trial of hemp as silage. No significant differences were found between yield of
the hemp and of barley/oat silage fed to heifers, suggesting that fermenting
hemp plants reduces possible harmful constituents.
Hemp as an Agricultural Barrier
One of the most curious uses of hemp is as a fence to prevent pollen transfer
in commercial production of seeds. Isolation distances for ensuring that seeds
produced are pure are considerable for many plants, and often impractical. At
one point in the 1980s, the only permitted use of hemp in Germany was as a fence
or hedge to prevent plots of beets being used for seed production from being
contaminated by pollen from ruderal beets. The high and rather inpenetrable
hedge that hemp can produce was considered unsurpassed by any other species for
the purpose. As well, the sticky leaves of hemp were thought to trap pollen.
However, Saeglitz et al. (2000) demonstrated that the spread of beet pollen is
not effectively prevented by hemp hedges. Fiber (i.e. tall) cultivars of hemp
were also once used in Europe as wind-breaks, protecting vulnerable crops
against wind damage. Although hemp plants can lodge, on the whole very tall hemp
is remarkably resistant against wind.
Bioremediation
Preliminary work in Germany (noted in Karus and Leson 1994) suggested that
hemp could be grown on soils contaminated with heavy metals, while the fiber
remained virtually free of the metals. Kozlowski et al. (1995) observed that
hemp grew very well on copper-contaminated soil in Poland (although seeds
absorbed high levels of copper). Baraniecki (1997) found similar results.
Mölleken et al. (1997) studied effects of high concentration of salts of copper,
chromium, and zinc on hemp, and demonstrated that some hemp cultivars have
potential application to growth in contaminated soils. It would seem unwise to
grow hemp as an oilseed on contaminated soils, but such a habitat might be
suitable for a fiber or biomass crop. The possibility of using hemp for
bioremediation deserves additional study.
Wildlife Uses
Hemp is plagued by bird predation, which take a heavy toll on seed
production. The seeds are well known to provide extremely nutritious food for
both wild birds and domestic fowl. Hunters and birdwatchers who discover wild
patches of hemp often keep this information secret, knowing that the area will
be a magnet for birds in the fall when seed maturation occurs. Increasingly in
North America, plants are being established to provide habitat and food for
wildlife. Hemp is not an aggressive weed, and certainly has great potential for
being used as a wildlife plant. Of course, current conditions forbid such usage
in North America.
Ornamental Forms
Hemp has at times in the past been grown simply for its ornamental value. The
short, strongly-branched cultivar ‘Panorama’ (Fig. 43) bred by Iván Bósca, the
dean of the world’s living hemp breeders, was commercialized in Hungary in the
1980s, and has been said to be the only ornamental hemp cultivar available. It
has had limited success, of course, because there are very few circumstances
that permit private gardeners can grow
Cannabis as an ornamental today.
By contrast, beautiful ornamental cultivars of opium poppy are widely cultivated
in home gardens across North America, despite their absolute illegality and the
potentially draconian penalties that could be imposed. Doubtless in the unlikely
event that it became possible, many would grow hemp as an ornamental.
Fig. 43. ‘Panorama,’ the world’s only ornamental cultivar, with the
breeder, Ivan Bócsa. (Courtesy of Professor Bócsa.)
AGRONOMY
The following sketch of hemp cultivation is insufficient to address all of
the practical problems that are encountered by hemp growers. Bócsa and Karus
(1998) is the best overall presentation of hemp growing available in English.
The reader is warned that this book, as well as almost all of the literature on
hemp, is very much more concerned with fiber production than oilseed production.
McPartland et al. (2000) is the best presentation available on diseases and
pests, which fortunately under most circumstances do limited damage. The
resource list presented below should be consulted by those wishing to learn
about hemp production. Provincial agronomists in Canada now have experience with
hemp, and can make local recommendations. Particularly good web documents are:
for Ontario (OMAFRA Hemp Series, several documents):
www.gov.on.ca/OMAFRA/english/crops/hort/hemp.html); for Manitoba (several
documents): www.gov.mb.ca/agriculture/crops/hemp/bko01s00.html; for British
Columbia: (BC Ministry of Agriculture and Foods Fact Sheet on Industrial Hemp,
prepared by A. Oliver and H. Joynt):
www.agf.gov.bc.ca/croplive/plant/horticult/specialty/specialty.htm
In the US, extension publications produced up to the end of World War II are
still useful, albeit outdated (Robinson 1935; Wilsie et al. 1942; Hackleman and
Domingo 1943; Wilsie et al. 1944).
Hemp does best on a loose, well-aerated loam soil with high fertility and
abundant organic matter. Well-drained clay soils can be used, but poorly-drained
clay soils are very inappropriate because of their susceptibility to compaction,
which is not tolerated. Young plants are sensitive to wet or flooded soils, so
that hemp must have porous, friable, well-drained soils. Sandy soils will grow
good hemp, provided that adequate irrigation and fertilization are provided, but
doing so generally makes production uneconomical. Seedbed preparation requires
considerable effort. Fall plowing is recommended, followed by careful
preparation of a seedbed in the spring. The seedbed should be fine, level, and
firm. Seed is best planted at 2–3 cm (twice as deep will be tolerated). Although
the seedlings will germinate and survive at temperatures just above freezing,
soil temperatures of 8°–10°C are preferable. Generally hemp should be planted
after danger of hard freezes, and slightly before the planting date of maize.
Good soil moisture is necessary for seed germination, and plenty of rainfall is
needed for good growth, especially during the first 6 weeks. Seeding rate is
specific to each variety, and this information should be sought from the
supplier. Fiber strains are typically sown at a minimum rate of 250 seeds per m2
(approximately 45 kg/ha), and up to three times this density is sometimes
recommended. In western Europe, seeding rates range from 60–70 kg/ha for fiber
cultivars. Recommendations for seeding rates for grain production vary widely,
from 10–45 kg/ha. Densities for seed production for tall, European, dual-purpose
cultivars are less than for short oilseed cultivars. Low plant densities, as
commonly found in growing tall European cultivars for seed, may not suppress
weed growth adequately, and under these circumstances resort to herbicides may
pose a problem for those wishing to grow hempseed organically. Hemp requires
about the same fertility as a high-yielding crop of wheat. Industrial hemp grows
well in areas that corn produces high yields. Growing hemp may require addition
of up to 110 kg/ha of nitrogen, and 40–90 kg/ha of potash. Hemp particularly
requires good nitrogen fertilization, more so for seed production than fiber.
Adding nitrogen when it is not necessary is deleterious to fiber production, so
that knowledge of the fertility of soils being used is very important. Organic
matter is preferably over 3.5%, phosphorus should be medium to high (>40
ppm), potassium should be medium to high (>250 ppm), sulfur good (>5,000
ppm), and calcium not in excess (<6,000 ppm).
Finding cultivars suited to local conditions is a key to success. Hemp
prefers warm growing conditions, and the best European fiber strains are
photoperiodically adapted to flowering in southern Europe, which provides
seasons of at least 4 months for fiber, and 5.5 months for seed production.
Asian land races are similarly adapted to long seasons. In Canada, many of the
available cultivars flower too late in the season for fiber production, and the
same may be predicted for the northern US. Fiber production should also be
governed by availability of moisture throughout the season, and the need for
high humidity in the late summer and fall for retting, so that large areas of
the interior and west of North America are not adapted to growing fiber hemp.
The US Corn Belt has traditionally been considered to be best for fiber hemp.
There are very few cultivars dedicated to oilseed production (such as ‘Finola’
and ‘Anka’) or that at least are known to produce good oilseed crops (such as
‘Fasamo’ and ‘Uniko-B’). Oilseed production was a specialty of the USSR, and
there is some likelihood that northern regions of North America may find
short-season, short-stature oilseed cultivars ideal.
Although hemp can be successfully grown continuously for several years on the
same land, rotation with other crops is desirable. A 3- or preferably 4-year
rotation may involve cereals, clover or alfalfa for green manure, maize, and
hemp. In Ontario it has been recommended that hemp not follow canola, edible
beans, soybeans or sunflowers. However, according to Bócsa and Karus (1998),
“
it matters little what crops are grown prior to hemp.”
For a fiber crop, hemp is cut in the early flowering stage or while pollen is
being shed, well before seeds are set. Tall European cultivars (greater than 2
m) have mostly been grown in Canada to date, and most of these are
photoperiodically adapted to mature late in the season (often too late). Small
crops have been harvested with sickle-bar mowers and hay swathers, but plugging
of equipment is a constant problem. Hemp fibers tend to wrap around combine
belts, bearings, indeed any moving part, and have resulted in large costs of
combine repairs (estimated at $10.00/ha). Slower operation of conventional
combines has been recommended (0.6–2 ha/hour). Large crops may require European
specialized equipment, but experience in North America with crops grown mainly
for fiber is limited. The Dutch company HempFlax has developed or adapted
several kinds of specialized harvesting equipment (Fig. 44, 45).
 |
 |
| Fig. 44. A John Deere Kemper harvester, with circular drums that cut
and chop hemp stalks, shown in operation in southern Ontario. (Courtesy of Kenex
Ltd., Pain Court, Ontario.) |
Fig. 45. A hemp harvester operated by HempFlax (Netherlands), with a
wide mowing head capable of cutting 3 m long stems into 0.6 m pieces, at a
capacity of 3 ha/hour. (Courtesy of HempFlax, Oude Pekela, The
Netherlands.) |
Retting is generally done in the field (Fig. 46, 47). This typically requires
weeks. The windrows should be turned once or twice. If not turned, the stems
close to the ground will remain green while the top ones are retted and turn
brown. When the stalks have become sufficiently retted requires experience—the
fibers should have turned golden or grayish in color, and should separate easily
from the interior wood. Baling can be done with any kind of baler (Fig. 48).
Stalks should have less than 15% moisture when baled, and should be allowed to
dry to about 10% in storage. Bales must be stored indoors. Retted stalks are
loosely held together, and for highest quality fiber applications need to be
decorticated, scutched, hackled, and combed to remove the remaining pieces of
stalks, broken fibers, and extraneous material. The equipment for this is rare
in North America, and consequently use of domestically-produced fiber for high
quality textile applications is extremely limited. However, as described above
relatively crude fiber preparations also have applications.
 |
 |
| Fig. 46. Windrowed fiber hemp in process of dew retting. Photograph
taken in 1930 on the Central Experimental Farm, Ottawa, Canada. |
Fig. 47. Shocked fiber hemp in process of dew retting. Photograph
taken in 1931, near Ottawa, Canada. The shocks shed water like pup-tents,
providing more even retting than windrows. |
Fig. 48. Baled, retted hemp straw. (Courtesy of Kenex Ltd., Pain
Court, Ontario.)
Harvesting tall varieties for grain is difficult. In France, the principal
grower of dual-purpose varieties, the grain is taken off the field first,
leaving most of the stalks for later harvest (Fig. 49). Putting tall whole
plants through a conventional combine results in the straw winding around moving
parts, and the fibers working into bearings, causing breakdown, fires, high
maintenance, and frustration. Following the French example of raising the
cutting blade to harvest the grain is advisable. Growing short varieties
dedicated to grain production eliminates many of the above problems, and since
the profitability of hemp straw is limited at present, seems preferable. Grain
growers should be aware that flocks of voracious birds are a considerable source
of damage to hempseed, particularly in small plantations.
Fig. 49. Harvesting hemp in France. (Courtesy of La Chanvrière de
l’Aube, Bar sur Aube, France.)
ECOLOGICAL FRIENDLINESS OF HEMP
Although the environmental and biodiversity benefits of growing hemp have
been greatly exaggerated in the popular press,
C. sativa is nevertheless
exceptionally suitable for organic agriculture, and is remarkably less
“ecotoxic” in comparison to most other crops (Montford and Small 1999b). Figure
50 presents a comparison of the ecological friendliness of
Cannabis crops
(fiber, oilseed, and narcotics) and 21 of the world’s major crops, based on 26
criteria used by Montford and Small (1999a) to compare the ecological
friendliness of crops.
Fig. 50. A crude comparison of the biodiversity friendliness of
selected major crops and three
Cannabis sativa crops (fiber, oilseed,
drug) based on 26 criteria (after Montford and Small 1999a).
The most widespread claim for environmental friendliness of hemp is that it
has the potential to save trees that otherwise would be harvested for production
of lumber and pulp. Earlier, the limitations of hemp as a pulp substitute were
examined. With respect to wood products, several factors appear to favor
increased use of wood substitutes, especially agricultural fibers such as hemp.
Deforestation, particularly the destruction of old growth forests, and the
world’s decreasing supply of wild timber resources are today major ecological
concerns. Agroforestry using tree species is one useful response, but
nevertheless sacrifices wild lands and biodiversity, and is less preferable than
sustainable wildland forestry. The use of agricultural residues (e.g. straw
bales in house construction) is an especially environmentally friendly solution
to sparing trees, but material limitations restrict use. Another chief advantage
of several annual fiber crops over forestry crops is relative productivity,
annual fiber crops sometimes producing of the order of four times as much per
unit of land. Still another important advantage is the precise control over
production quantities and schedule that is possible with annual crops. In many
parts of the world, tree crops are simply not a viable alternative. “
By the
turn of the century 3 billion people may live in areas where wood is cut faster
than it grows or where fuelwood is extremely scarce” (World Commission on
Environment and Development 1987). “
Since mid-century, lumber use has
tripled, paper use has increased six-fold, and firewood use has soared as Third
World populations have multiplied” (Brown et al. 1998). Insofar as hemp
reduces the need to harvest trees for building materials or other products, its
use as a wood substitute will tend to contribute to preserving biodiversity.
Hemp may also enhance forestry management by responding to short-term fiber
demand while trees reach their ideal maturation. In developing countries where
fuelwood is becoming increasingly scarce and food security is a concern, the
introduction of a dual-purpose crop such as hemp to meet food, shelter, and fuel
needs may contribute significantly to preserving biodiversity.
The most valid claims to environmental friendliness of hemp are with respect
to agricultural biocides (pesticides, fungicides, herbicides).
Cannabis
sativa is known to be exceptionally resistant to pests (Fig. 51), although,
the degree of immunity to attacking organisms has been greatly exaggerated, with
several insects and fungi specializing on hemp. Despite this, use of pesticides
and fungicides on hemp is usually unnecessary, although introduction of hemp to
regions should be expected to generate local problems.
Cannabis sativa is
also relatively resistant to weeds, and so usually requires relatively little
herbicide. Fields intended for hemp use are still frequently normally cleared of
weeds using herbicides, but so long as hemp is thickly seeded (as is always done
when hemp is grown for fiber), the rapidly developing young plants normally
shade out competing weeds.
Fig. 51. Grasshopper on hemp. Most insects cause only limited damage
to hemp, and substantial insect damage is uncommon, so the use of insecticides
is very rarely required.
BREEDING HEMP FOR NORTH AMERICA
The basic commercial options for growing hemp in North America is as a fiber
plant, an oilseed crop, or for dual harvest for both seeds and fiber. Judged on
experience in Canada to date, the industry is inclined to specialize on either
fiber or grain, but not both. Hemp in our opinion is particularly suited to be
developed as an oilseed crop in North America. The first and foremost breeding
goal is to decrease the price of hempseed by creating more productive cultivars.
While the breeding of hemp fiber cultivars has proceeded to the point that only
slight improvements can be expected in productivity in the future, the genetic
potential of hemp as an oilseed has scarcely been addressed. From the point of
view of world markets, concentrating on oilseed hemp makes sense, because Europe
has shown only limited interest to date in developing oilseed hemp, whereas a
tradition of concentrating on profitable oilseed products is already well
established in the US and Canada. Further, China’s supremacy in the production
of high-quality hemp textiles at low prices will be very difficult to match,
while domestic production of oilseeds can be carried out using technology that
is already available. The present productivity of oilseed hemp—about 1 t/ha
under good conditions, and occasional reports of 1.5 to 2 t/ha, is not yet
sufficient for the crop to become competitive with North America’s major
oilseeds. We suggest that an average productivity of 2 t/ha will be necessary to
transform hempseed into a major oilseed, and that this breeding goal is
achievable. At present, losses of 30% of the seed yields are not uncommon, so
that improvements in harvesting technology should also contribute to higher
yields. Hemp food products cannot escape their niche market status until the
price of hempseed rivals that of other oilseeds, particularly rapeseed, flax,
and sunflower. Most hemp breeding that has been conducted to date has been for
fiber characteristics, so that there should be considerable improvement
possible. The second breeding goal is for larger seeds, as these are more easily
shelled. Third is breeding for specific seed components. Notable are the
health-promoting gamma-linolenic acid; improving the amino acid spectrum of the
protein; and increasing the antioxidant level, which would not only have health
benefits but could increase the shelf life of hemp oil and foods.
Germplasm Resources
Germplasm for the improvement of hemp is vital for the future of the industry
in North America. However, there are no publicly available germplasm banks
housing
C. sativa in North America. The hundreds of seed collections
acquired for Small’s studies (reviewed in Small 1979) were destroyed in 1980
because Canadian government policy at that time envisioned no possibility that
hemp would ever be developed as a legitimate crop. An inquiry regarding the 56
United States Department of Agriculture hemp germplasm collections supplied to
and grown by Small and Beckstead (1973) resulted in the reply that there are no
remaining hemp collections in USDA germplasm holdings, and indeed that were such
to be found they would have to be destroyed. While hemp has been and still is
cultivated in Asia and South America, it is basically in Europe that germplasm
banks have made efforts to preserve hemp seeds. The Vavilov Institute of Plant
Research in St. Petersburg, Russia has by far the largest germplasm collection
of hemp of any public gene bank, with about 500 collections. Detailed
information on the majority of hemp accessions of the Vavilov Institute can be
found in Anon. (1975). Budgetary problems in Russia have endangered the survival
of this invaluable collection, and every effort needs to be made to find new
funding to preserve it. Maintenance and seed generation issues for the Vavilov
hemp germplasm collection are discussed in a number of articles in the Journal
of the International Hemp Association (Clarke 1998b; Lemeshev et al. 1993,
1994). The Gatersleben gene bank of Germany, the 2nd largest public gene bank in
Europe, has a much smaller
Cannabis collection, with less than 40
accessions (detailed information on the hemp accessions of the Gatersleben gene
bank are available at fox-serv.ipk-gatersleben.de/). Because hemp is regaining
its ancient status as an important crop, a number of private germplasm
collections have been assembled for the breeding of cultivars as commercial
ventures (de Meijer and van Soest 1992; de Meijer 1998), and of course these are
available only on a restricted basis, if at all.
The most pressing need of the hemp industry in North America is for the
breeding of more productive oilseed cultivars. At present, mainly European
cultivars are available, of which very few are suitable for specialized oilseed
production. More importantly, hempseed oil is not competitive, except in the
novelty niche market, with the popular food oils. As argued above, to be
competitive, hemp should produce approximately 2 t/ha; at present 1 t/ha is
considered average to good production. Doubling the productive capacity of a
conventional crop would normally be considered impossible, but it needs to be
understood just how little hemp has been developed as an oilseed. There may not
even be extant land races of the kind of hemp oilseed strains that were once
grown in Russia, so that except for a very few very recent oilseed cultivars,
there has been virtually no breeding of oilseed hemp. Contrarily, hemp has been
selected for fiber to the point that some breeders consider its productivity in
this respect has already been maximized. Fiber strains have been selected for
low seed production, so that most hemp germplasm has certainly not been selected
for oilseed characteristics. By contrast, drug varieties have been selected for
very high yield of flowers, and accordingly produce very high yield of seeds.
Drug varieties have been observed to produce more than a kilogram of seed per
plant, so that a target yield of several tonnes per hectare is conceivable
(Watson and Clarke 1997). Of course, the high THC in drug cultivars makes these
a difficult source of germplasm. However, wild plants of
C. sativa have
naturally undergone selection for high seed productivity, and are a particularly
important potential source of breeding germplasm.
Wild North American hemp is derived mostly from escaped European cultivated
hemp imported in past centuries, perhaps especially from a revival of
cultivation during World War II. Wild Canadian hemp is concentrated along the
St. Lawrence and lower Great Lakes, where considerable cultivation occurred in
the 1800s. In the US, wild hemp is best established in the American Midwest and
Northeast, where hemp was grown historically in large amounts. Decades of
eradication have exterminated many of the naturalized populations in North
America. In the US, wild plants are rather contemptuously called “ditch weed” by
law enforcement personnel. However, the attempts to destroy the wild populations
are short-sighted, because they are a natural genetic reservoir, mostly low in
THC. Wild North American plants have undergone many generations of natural
adaptation to local conditions of climate, soil and pests, and accordingly it is
safe to conclude that they harbor genes that are invaluable for the improvement
of hemp cultivars. We have encountered exceptionally vigorous wild Canadian
plants (Fig. 52), and grown wild plants from Europe (Fig. 53) which could prove
valuable. Indeed, studies are in progress in Ontario to evaluate the agronomic
usefulness of wild North American hemp. Nevertheless, present policies in North
America require the eradication of wild hemp wherever encountered. In Europe and
Asia, there is little concern about wild hemp, which remains a valuable
resource.
 |
 |
| Fig. 52. Wild female hemp plant collected Oct. 17, 2000
near Ottawa, Canada. This vigorous plant had a fresh weight of 1.5 kg. |
Fig. 53. A wild female hemp plant grown in southern Ontario
[accession #16 from Georgia (formerly USSR), reported in Small and Marcus
(2000)]. Such highly-branched plants can produce very large quantities of seeds,
and may be useful for breeding. |
HARD LESSONS FOR FARMERS
It is clear that there is a culture of idealistic believers in hemp in North
America, and that there is great determination to establish the industry. As
history has demonstrated, unbridled enthusiasm for largely untested new crops
touted as gold mines sometimes leads to disaster. The attempt to raise silk in
the US is probably the most egregious example. In 1826 a Congressional report
that recommended the preparation of a practical manual on the industry resulted
in a contagious desire to plant mulberries for silk production, with the
eventual collapse of the industry, the loss of fortunes, and a legacy of
“Mulberry Streets” in the US (Chapter 2, Bailey 1898). In the early 1980s in
Minnesota, Jerusalem artichoke was touted as a fuel, a feed, a food, and a sugar
crop. Unfortunately there was no market for the new “wonder crop” and hundreds
of farmers lost about $20 million (Paarlberg 1990). The level of “hype”
associated with industrial hemp is far more than has been observed before for
other new crops (Pinfold Consulting 1998). Probably more so than any plant in
living memory, hemp attracts people to attempt its cultivation without first
acquiring a realistic appreciation of the possible pitfalls. American presidents
George Washington and Thomas Jefferson encouraged the cultivation of hemp, but
both lost money trying to grow it. Sadly in Canada in 1999 numerous farmers
contracted to grow half of Canada’s crop area for hemp for the American-based
Consolidated Growers and Processors, and with the collapse of the firm were left
holding very large amounts of unmarketable grain and baled hemp straw. This has
represented a most untimely setback for a fledgling industry, but at least has
had a sobering effect on investing in hemp. In this section we emphasize why
producers should exercise caution before getting into hemp.
In Europe and Asia, hemp farming has been conducted for millennia. Although
most countries ceased growing hemp after the second word war, some didn’t,
including France, China, Russia, and Hungary, so that essential knowledge of how
to grow and process hemp was maintained. When commercial hemp cultivation
resumed in Canada in 1997, many farmers undertook to grow the crop without
appreciating its suitability for their situation, or for the hazards of an
undeveloped market. Hemp was often grown on farms with marginal incomes in the
hopes that it was a savior from a downward financial spiral. The myth that hemp
is a wonder crop that can be grown on any soil led some to cultivate on soils
with a history of producing poor crops; of course, a poor crop was the result.
Market considerations also heavily determine the wisdom of investing in hemp.
Growing hemp unfortunately has a magnetic attraction to many, so there is danger
of overproduction. A marketing board could be useful to prevent unrestrained
competition and price fluctuations, but is difficult to establish when the
industry is still very small. As noted above, unwise investment in Canada
produced a glut of seeds that resulted in price dumping and unprofitable levels
for the majority. Cultural and production costs of hemp have been said to be
comparable to those for corn, and while the truth of this remains to be
confirmed, the legislative burden that accompanies hemp puts the crop at a
unique disadvantage. Among the problems that Canadian farmers have faced are the
challenge of government licensing (some delays, and a large learning curve),
very expensive and sometime poor seed (farmers are not allowed to generate their
own seed), teenagers raiding fields in the mistaken belief that marijuana is
being grown, and great difficulties in exportation because of the necessity of
convincing authorities that hemp is not a narcotic. Unless the producer
participates in sharing of value-added income, large profits are unlikely. The
industry widely recognizes that value added to the crop is the chief potential
source of profit, as indeed for most other crops.
THE POLITICS OF CANNABIS WITH PARTICULAR REFERENCE TO THE US
Cannabis has long had an image problem, because of the extremely
widespread use of “narcotic” cultivars as illegal intoxicants. The US Drug
Enforcement Administration has the mandate of eliminating illicit and wild
marijuana, which it does very well (Fig. 54–56). Those interested in
establishing and developing legitimate industries based on fiber and oilseed
applications have had to struggle against considerable opposition from many in
the political and law enforcement arenas. The United States National Institute
on Drug Abuse (NIDA) information web site on marijuana, which reflects a
negative view of cannabis, is at www.nida.nih.gov/DrugPages/Marijuana.html, and
reflects several basic fears: (1) growing
Cannabis plants makes law
enforcement more difficult, because of the need to ensure that all plants
cultivated are legitimate; (2) utilization of legitimate
Cannabis
products makes it much more difficult to maintain the image of the illegitimate
products as dangerous; (3) many in the movements backing development of hemp are
doing so as a subterfuge to promote legalization of recreational use of
marijuana; and (4) THC (and perhaps other constituents) in
Cannabis are
so harmful that their presence in any amount in any material (food, medicine or
even fiber product) represents a health hazard that is best dealt with by a
total proscription.
 |
 |
| Fig. 54. The war on drugs: helicopter spraying of Paraquat
herbicide on field of marijuana. (Courtesy US Drug Enforcement
Administration.) |
Fig. 55. The war on drugs: clandestine indoor marijuana
cultivation. (Courtesy US Drug Enforcement
Administration.) |
Fig. 56. The war on drugs: burning seized marijuana. (Courtesy US Drug
Enforcement Administration.)
Ten years ago hemp cultivation was illegal in Germany, England, Canada,
Australia, and other countries. Essential to overcoming governmental reluctance
in each country was the presentation of an image that was business-oriented, and
conservative. The merits of environmentalism have acquired some political
support, but unless there is a reasonable possibility that hemp cultivation is
perceived as potentially economically viable, there is limited prospect of
having anti-hemp laws changed. Strong support from business and farm groups is
indispensable; support from pro-marijuana interests and what are perceived of as
fringe groups is generally counterproductive. It is a combination of prospective
economic benefit coupled with assurance that hemp cultivation will not
detrimentally affect the enforcement of marijuana legislation that has led most
industrially advanced countries to reverse prohibitions against growing hemp.
Should the US permit commercial hemp cultivation to resume, it will likely be
for the same reasons.
The US Office of National Drug control Policy issued a statement on
industrial hemp in 1997 (www.whitehousedrugpolicy.gov/policy/hemp%5Fold.html)
which included the following: “
Our primary concern about the legalization of
the cultivation of industrial hemp (Cannabis sativa
) is the message it
would send to the public at large, especially to our youth at a time when
adolescent drug use is rising rapidly... The second major concern is that
legalizing hemp production may mean the de facto legalization of marijuana
cultivation. Industrial hemp and marijuana are the product of the same plant,
Cannabis sativa
... Supporters of the hemp legalization effort claim hemp
cultivation could be profitable for US farmers. However, according to the USDA
and the US Department of Commerce, the profitability of industrial hemp is
highly uncertain and probably unlikely. Hemp is a novelty product with limited
sustainable development value even in a novelty market... For every proposed use
of industrial hemp, there already exists an available product, or raw material,
which is cheaper to manufacture and provides better market results.... Countries
with low labor costs such as the Philippines and China have a competitive
advantage over any US hemp producer.”
Recent European Commission proposals to change its subsidy regime for hemp
contained the following negative evaluation of hemp seed: “
The use of hemp
seed ... would, however, even in the absence of THC, contribute towards making
the narcotic use of cannabis acceptable... In this light, subsidy will be denied
producers who are growing grain for use in human nutrition and
cosmetics.”
A USDA analysis of hemp, “
Industrial hemp in the United States: Status and
market potential,” was issued in 2000, and is available at
www.ers.usda.gov/publications/ages001e/index.htm. This is anonymously-authored,
therefore presumably represents a corporate or “official” evaluation. The
conclusion was that “
US markets for hemp fiber (specialty textiles, paper,
and composites) and seed (in food or crushed for oil) are, and will likely
remain, small, thin markets. Uncertainty about longrun demand for hemp products
and the potential for oversupply discounts the prospects for hemp as an
economically viable alternative crop for American farmers.” Noting the
oversupply of hempseeds associated with Canada’s 12,000 ha in 1999, the report
concluded that the long term demand for hemp products is uncertain, and predicts
that the hemp market in the US will likely remain small and limited. With
respect to textiles, the report noted the lack of a thriving textile flax
(linen) US industry (despite lack of legal barriers), so that it would seem
unlikely that hemp could achieve a better market status. With respect to hemp
oil, the report noted that hemp oil in food markets is limited by its short
shelf life, the fact that it can not be used for frying, and the lack of US Food
and Drug Administration approval as GRAS (“generally recognized as safe”).
Moreover, summarizing four state analyses of hemp production (McNulty 1995,
Ehrensing 1998, Kraenzel et al. 1998, Thompson et al. 1998), profitability
seemed doubtful.
Without arguing the merits of the above contentions, we point out that the
legitimate use of hemp for non-intoxicant purposes has been inhibited by the
continuing ferocious war against drug abuse. In this atmosphere, objective
analysis has often been lacking. Unfortunately both proponents and opponents
have tended to engage in exaggeration. Increasingly, however, the world is
testing the potential of hemp in the field and marketplace, which surely must be
the ultimate arbiters. De Guzman (2001), noting the pessimistic USDA report,
observed that “
Nevertheless, others point to the potential of [the] market.
Hemp products have a growing niche market of their own, and the market will
remain healthy and be well supported with many competing brands.”
A wide variety of hemp clothing, footwear, and food products are now
available in North America. Some American manufacturers and distributors have
chosen to exploit the association of hemp products with marijuana in their
advertising. Such marketing is unfortunate, sending the message that some in the
industry are indifferent to the negative image that this generates in the minds
of much of the potential consuming public. Admittedly, such advertising works.
But marketing based on the healthful and tasteful properties of hemp food
products, the durable nature of hemp textiles, and the environmental advantages
of the crop has proven to be widely acceptable, and is likely to promote the
long term development of hemp industries.
Will hemp commercial cultivation resume in the US in the foreseeable future?
This is difficult to judge, but the following considerations suggest this might
occur: (1) increasing awareness of the differences between industrial hemp and
marijuana; (2) growing appreciation of the environmental benefits of hemp
cultivation; (3) continuing demonstration of successful hemp cultivation and
development in most of the remaining western world; all the G8 countries, except
the US, produce and export industrial hemp; and (4) increasing pressure on state
and federal governments to permit hemp cultivation by farmers, particularly
wheat, corn, and tobacco farmers in desperate need of substitute crops, but also
for rotation crops to break pest and disease cycles.
More than a century ago, an expert on hemp concluded his manual on
hemp-growing in the US by stating “
There is no question that when the
inventive genius, comprehension and energies of the American people become
interested, another grand source of profitable employment and prosperity will be
established” (Boyce 1900).
MARKET DEVELOPMENT
Individual entrepreneurs, and indeed whole industries, as a matter of
economic survival need to adopt a clear investment policy with respect to
whether their market is to be output-driven or demand-led. From the individual
producer’s perspective, the old adage “
find your market before you plant your
seed” remains sound advice.
In the mid 1990s, the EU provided subsidization for hemp cultivation of ca.
$1,050/ha. This support was instrumental in developing a hemp industry in
western Europe. However, no comparable support is available in North America,
and indeed those contemplating entering into hemp cultivation are faced with
extraordinary costs and/or requirements in connection with licensing, security,
THC analysis, and record keeping. Those involved in value-added processing and
distribution are also faced with legal uncertainties and the regular threat of
idiosyncratic, indeed irrational actions of various governments. Simply
displaying a
C. sativa leaf on advertising has led to the threat of
criminal charges in the last decade in several G8 countries. Attempting to
export or import hemp products among countries is presently a most uncertain
activity.
It often takes 10 to 15 years for the industry associated with a new
agricultural crop to mature. While it is true that foreign imports have been the
basis for hemp products in North America for at least a decade, North American
production is only 4 years of age in Canada, and farming of hemp in the US has
not even begun. Viewed from this perspective, the hemp industry in North America
is still very much in its infancy. Varieties of hemp specifically suited to
given products and regions have only started to be developed in North America.
There is considerable uncertainty regarding yields, costs of production,
harvesting and processing equipment, product characteristics, foreign
competition, governmental support, and the vagaries of the regulatory
environment. Hemp is not presently a standard crop, and is likely to continue
experiencing the risks inherent in a small niche market for some time. Hemp is
currently a most uncertain crop, but has such a diversity of possible uses, is
being promoted by extremely enthusiastic market developers, and attracts so much
attention that it is likely to carve out a much larger share of the North
American marketplace than its detractors are willing to concede.
Given the uncertainties and handicaps associated with hemp, it is fortunate
that there are compensating factors. As noted, as a crop hemp offers some real
environmental advantages, particularly with regard to the limited needs for
herbicides and pesticides. Hemp is therefore pre-adapted to organic agriculture,
and accordingly to the growing market for products associated with
environmentally-friendly, sustainable production. Hemp products are an
advertiser’s dream, lending themselves to hyperbole (“healthiest salad oil in
the world,” “toughest jeans on the market”). While the narcotics image of
C.
sativa is often disadvantageous, advertisers who choose to play up this
association do so knowing that it will attract a segment of the consuming
population. In general, the novelty of hemp means that many consumers are
willing to pay a premium price. It might also be said that those who have
entered the hemp industry have tended to be very highly motivated, resourceful,
and industrious, qualities that have been needed in the face of rather
formidable obstacles to progress.
INFORMATION RESOURCES
Organizations
- North American Industrial Hemp Council Inc.: www.naihc.org
- Hemp Industries Association: www.thehia.org
- International Hemp Association: mojo.calyx.net/~olsen/HEMP/IHA/
- Hemp Food Association: hempfood.com/
- Ontario Hemp Alliance: www.ontariohempalliance.org
- International Association for Cannabis as Medicine:
www.acmed.org/english/main.htm
Web
- The Hemp Commerce & Farming Report: www.hempreport.com
- Industrial hemp information network: www.hemptech.com
Journals
From Thursday, June 7th through Saturday, June 9th, the Texas Democratic Party held their state convention in Houston, Texas. Along side other election related business such as selecting delegates, they also voted on their party platform for 2012. One of the issues added this year was support for marijuana decriminalization. Below you can read the official language:
