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Book reviews
Memoirs of an apostle of hemp.
Cultivation of hemp. Botany, cultivars, cultivation and harvesting. Ivan Bócsa and Michael Karus, 1997. Der Hanfanbau. Botanik, Sorten, Anbau und Ernte. C.F. Müller Verlag, Hüthig GmbH, Heidelberg, Germany. 173 pp., DM 38.
During July of 1990, Dr. Ivan Bócsa
received three young and aspiring Dutch agronomic researchers (myself among them) who had
come to Kompolt, Hungary to learn about hemp. Even during dinner (excellent food and
wine, I might add), they continued questioning him. When he was asked whether their
endless questions were tiring him, he proclaimed: “I am the apostle of hemp” and
invited them to continue, obviously enjoying their interest in “his” crop.
Fortunately for us, this “apostle” has now published a book on hemp that
essentially amounts to his memoirs.
For some strange reason, recent books on hemp
often are written by people whose “hands-on” Cannabis experience is
limited mainly to marijuana. Such books tend only to repeat the mix of facts,
fiction and wishful thinking found in other books on hemp written by those of like
background. The book “Der Hanfanbau” (in German, an English version is in
preparation) breaks that tradition, as it is written by somebody who actually knows what
he is talking about.
Professor Bócsa is the eldest, and one of the
most successful, active hemp breeders of Europe. This book summarizes his more than
forty years of hemp experiences. The book focuses on botany, breeding, cultivars,
climate and soil requirements, fertilization, plant density, pests, diseases, and harvest
technology. Dr. Bócsa collaborated with the well-known German hemp researcher
Michael Karus to translate his mainly Hungarian experience into recommendations for German
pedoclimatic conditions. Karus wrote the last two chapters of the book concerning
the environmental impact of hemp cultivation and the future of hemp in western Europe (new
processing technology and products).
As this book is a very valuable source of both
theoretical and practical information for anyone concerned with the cultivation of hemp,
it will no doubt enjoy several printings. However, in the next edition, the authors
might consider a few revisions. First, improving the technical quality of the
photographs would make the book even more attractive. For the more
scientifically-minded, the book could also be improved by the authors more rigorously
acknowledging their sources. In the current edition, references are too vague and
often missing. Finally, a few mistakes need correction. On page 28, an area
per plant of 2,000 cm2 is equated to a density of 20
plants/m2. This should be 5 plants/m2
(since each m2 contains 10,000 cm2).
On page 132, it is stated that at seed rates of less than 40 kg/ha, the crop’s
potential to suppress weeds is insufficient. That seems overly cautious, as this
reviewer has seen excellent weed suppression by hemp crops grown at a plant density of 65
plants/m2 (seed rate 13 kg/ha) on quite weedy soils.
The author also states on page 133: “Hemp reaches already 2 - 3 weeks after
sowing (beginning of May) a closed canopy ...”. This is somewhat exaggerated,
since in a warm spring (in northwestern Europe) hemp will take about one week to emerge
after being sown and another four weeks to reach canopy closure (which is rapid relative
to other crops).
Apart from these minor problems, the book
contains a wealth of information regarding the cultivation of hemp and will prove of much
value to present and future generations of breeders and agronomists working with this
fascinating crop.
Hayo van der Werf
Hemp: Highest overall score on ecological criteria
Sustainability of energy crops in Europe. A methodology developed and applied. E. E. Biewinga and G. van der Bijl, 1996. Centre for Agriculture and Environment, P.O. Box 10015, 3505 AA Utrecht, The Netherlands. 209 pp., NLG 55.
This report (in English) presents and
applies a method to assess the sustainability of energy crops (amongst which is hemp).
Its objectives are (1) to compare energy crops with respect to their ecological and
socio-economic sustainability, and (2) to compare energy crops with other crops and with
other energy sources. The proposed method has much in common with both the
well-known Life Cycle Assessment, and the less-known German Ganzheitliche Bilanzierung
(Overall Balancing) methods, as well as containing elements of the Environmental Impact
Assessment method. It assesses the effects of the cultivation and use of energy
crops on 12 ecological criteria: energy balance; emissions of gases
(“greenhouse-effect” promoting, acidifying , and ozone-depleting); emissions of
mineral salts (fertilizers) and pesticides to soil and water; soil erosion; groundwater
depletion; use of resources; waste production and utilization; and contributions to
biodiversity and to landscape values, as well as socio-economic criteria: price of the
energy produced, cost of abated CO2 emissions, and
employment created per hectare. The method is used to assess the sustainability of
10 potentially interesting energy crops (rape seed, sugar beet, winter wheat, sweet
sorghum, silage maize, hemp, Miscanthus, poplar, willow and Eucalyptus) in four regions in
Europe: North Netherlands, Hessen (Germany), East Anglia (England) and South Portugal.
With respect to ecological assessment, the
results are as follows.
The weighted average on socio-economic
criteria is the highest for willow, poplar and hemp, when co-firing with coal is the
conversion route. Production of electricity from hemp has the highest overall score
on ecological criteria and a good score on economic criteria. In Hessen, North
Netherlands and in East Anglia, hemp has the highest score on ecological sustainability.
Apart from maize, in all three areas hemp has the highest net energy budget and the
highest net greenhouse gas budget. Only for erosion and water use is hemp reported
to be ecologically less sustainable than most other crops.
This report presents what is probably the first
evaluation of environmental impact of the cultivation of hemp, relative to that of other
crops. The authors seem to have done a good job overall, although they might have
paid some more attention to technical details. Their assumption, for instance, that
a Cannabis crop which is harvested on the 16th of September in the Netherlands
can be left to dry in the field is rather surprising, as this month is often is very
rainy. The authors also (wrongly) assume that the use of fungicides makes agronomic
sense for hemp: obviously they did not make full use of the available literature.
The outcome of this study is, nonetheless, very interesting to those of us involved with
this crop. However, these results are based on a large number of suppositions and
require rigorous experimental verification.
Hayo van der Werf
Hemp product lines project
Das Hanfproduktlinienprojekt. 1997. Study of the Nova Institute in cooperation with IAF/FH Reutlingen and Ifeu-Institute Heidelberg (Germany), 490 pp. DM 200. Contact address: Nova Institute, Thielstrasse 35, 50354 Hürth, Germany, fax +2233 978369.
Outstanding is the right word with which to
begin this review of a book that gives a complete analysis of potential hemp product lines
feasible within the next few years in Germany. However, most of the discussed
product lines are also applicable in the rest of Europe or even the World. The
approach is very practical, in contrast to many other books on the subject. Data
were gathered from both the scientific literature and practical research. Normally
one could expect a boring scientific report, but this book is different. Opinions
and analyses of a large number of experts are used in combination with the presented data
and have an effect on the conclusions. It makes this analysis very readable and
realistic.
The book starts with such basics as botany,
seed oil, the cannabinoids and fibres. If you ever need data on such fibre qualities
as, content, length, or development you can find it in this book and if not, there are
more than 400 recent references. A central question of this book concerns products
that could find their way into industry in an economical and ecologically sound way.
Product lines are advocated to have a more industrial character, starting in the
field. Meaning, a fully mechanized harvest should be implemented, as practiced in
the Netherlands or England, where large bales of hemp straw are delivered to the factory.
It is shown that the EU subsidy plays a very important role in the final price of
hemp straw. Also important is, of course, harvest yield and transport distance.
The second step in most product lines, is the
separation of fibre from the hurds. This is mostly a mechanical process. Only
one process uses ultra-sound, but is still in a pilot phase. Five manufacturers of
fibre separation equipment are discussed. Prices for different types of extracted
fibre are calculated for the separation lines of each manufacturer. The obtained
fibre can be used in paper, car interiors, geotextiles, felt-like materials or
fibre-reinforced synthetics. For other applications, further fibre refinement is
required. This can be done mechanically or chemo-mechanically, then the fibre used
for textile applications or insulation material.
In total, 11 favored production lines were
selected and fully ana-lyzed with respect to technology, ecology and economy:
Fibre:
Non-fibre:
An important and new element in these
analyses is an ecological analysis of every step in the production chain: Use of
resources, use of natural space, production of green house gasses, effect on ozone,
production of acid rain, eutrophication, toxicity to humans and other organisms, smog and
noise production, etc. The ecological advantage of hemp is most clear in the first
production steps. For example, few or no pesticides are used. The last
production steps show, in general, a less pronounced advantage in comparison to other
products.
Unfortunately for most readers, this book is in
German. It would take a tremendous amount of work to make an English version, but it
would be well worth it. A mere abstract would not do, as the work’s strength
lies in its myriad details.
I would highly recommend this book to everyone
that would like to know more about the state-of-the-art in hemp processing technology and
economy.
Sebastiaan Hennink
E-mail: Shennink@User.DiVa.nl
Marihuana as medicine
Health Council of the Netherlands: Standing Committee on Medicine. Rijswijk: Health Council of the Netherlands, 1996; publication no. 1996/21E. ISBN: 90-5549-152-7
The ongoing popular practice of
self-medication with cannabis, recent changes in cannabis legislation in the States of
Arizona and California, and increasing scientific, commercial and media interest in
“medical marijuana” are putting considerable pressure on governments to
re-examine the therapeutic potential of cannabis and cannabinoids. It was not
unexpected then that, in late August 1996, the Minister of Health, Welfare and Sport
requested the Health Council of the Netherlands to supply scientific information about the
medical use of marijuana and related compounds. The resulting report “Marihuana
as medicine” by the Health Council’s Standing Committee on Medicine was
published in December of the same year. The Committee based its report largely on
the literature of the last 25 years. It adhered strictly to its remit, thus wisely
avoiding the quite separate issue of recreational marijuana. Four main potential
therapeutic applications of marijuana and cannabinoids were identified: the management of
chemotherapy-induced nausea and vomiting, appetite stimulation in AIDS and cancer
patients, skeletal muscle relaxation and tremor suppression in multiple sclerosis, and
reduction of intraocular pressure in glaucoma. The principal conclusions of the
Committee were firstly, that there is insufficient scientific evidence to justify the
prescription of marijuana or cannabinoids, secondly that physicians should not have to
accept responsibility for a natural product of unknown composition that has not been
subjected to quality control and thirdly that it should be left to individual patients to
decide whether or not to self-medicate with marijuana (in whatever form). The Report
also highlights a lack of scientific data comparing the use of marijuana with that of
individual cannabinoids.
With regard to the first of these conclusions,
there is no doubt that more experiments are required to validate the claimed therapeutic
benefits of marijuana. However, it is puzzling that the Committee was unable to
concede that individual cannabinoids do have a place in modern medicine, at least for the
management of chemotherapy-induced nausea and vomiting and for appetite stimulation, as
the first of these applications is approved in the UK (for the cannabinoid analogue,
nabilone) and both are approved in the USA and elsewhere (for THC). It is also
surprising that the Committee considered marijuana of unknown composition to pose such a
serious problem for physicians, as a standard preparation could easily be produced.
One such preparation, tincture of Cannabis, was available to physicians for
prescription in the UK until 1971 and, indeed, it is often forgotten that the British
Advisory Committee on Drug Dependence concluded in its 1968 report to the Home Office1 that “Preparations of Cannabis and its
derivatives should continue to be available on prescription for purposes of medical
treatment and research”.
Finally, although the Health Council’s
Standing Committee on Medicine performed its allotted task, it is disappointing that
having accepted that some patients self-medicate with cannabis, it did not go further by
pointing out possible medical problems associated with this practice. It is of
particular concern that patients presently take cannabis without any guidance from a
physician as to the preferred route of administration (cannabis need not be smoked), the
appropriate dosage and any serious side effects that they might experience, especially if
they are pregnant, or have angina or a predisposition to schizophrenia. It is also
cause for concern that instead of having access to a standard preparation of cannabis from
a reliable source, patients can currently only obtain cannabis of potency and pedigree
that is both variable and unknown.
1. Cannabis. Report by the Advisory Committee on Drug Dependence, p. 33, paragraph 101, sub paragraph 12. Her Majesty s Stationery Office, London, 1968.
Roger Pertwee