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:


        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