I commend the Journal for the high level of objectivity to which it aspires. You provide
an important service as a forum
for public dissertation and debate. A recent article1 in your journal disputes two statements in
my book, Hemp, Lifeline to
the Future.2 I wish to respond to those comments.
Popular Mechanics magazine published a 1938 article3 [which states] that the woody core of hemp is "77 percent cellulose". I have since come to agree with you that their figure is incorrect. My review of scientific and technical literature indicates a cellulose content in the core ranging from 30 percent to around 40 percent. I see two possible explanations for the magazine's error. The writer may have inadvertently combined the cellulose content with hemi-cellulose, since together they approximate the stated figure. Or perhaps he meant not the core but the bark, which can surpass 77 percent cellulose.
Moving on, you dispute my statement that hemp produces "a larger amount of dry vegetable matter than any other crop in temperature climates" (p. 72). This is quoted verbatim from the 1913 US Department of Agriculture report entitled "Hemp".4 Dewey clearly referred to the horticulture of his day with conventional farming techniques to produce annual rotational crops in a sustainable manner. The context as I described it excludes tropical, aqua culture, tree farming and genetically mutated crops. History shows us that hemp is a long-term crop that gives high yields on good soil using only natural organic fertilizers (e.g., manure and compost) and crop rotation. While a few crops can equal or surpass hemp's short term annual output, most of these require more water and attention during the growing season.
Furthermore, modern hemp reports come from different soils, different climates, different farming techniques, even different seeds lines than he used. No wonder they get different results. Genetics may be the defining issue. Dewey hybridized choice seeds from Europe with the best of China. He bred for maximum yields, not minimum THC, and he got a higher output under sustainable conditions. Perhaps THC plays a greater role in hemp output than is politically correct to admit. Perhaps the US government's century of hemp seed selection resulted in the most successful hemp breeding program ever achieved. Or perhaps you're right, and Dewey overstated his case. His hybrids were destroyed by the drug war, so we will never know for sure.
I hope to see some work done around the variables discussed here for a more accurate assessment of hemp's potential. Nevertheless, there is no mistaking Dewey's enthusiasm for Cannabis. It is an enthusiasm which I share, and I know you do, too.
Author of Hemp, Lifeline to the Future
Director of the Business Alliance for Commerce in Hemp
President of the Hemp Industries Association
1 Werf, H.M.G. van der, 1994. Hemp facts and hemp fiction. JIHA 1: 58.
2 Conrad, Chris 1994. Hemp, Lifeline to the Future. Creative Xpressions. Los Angeles California.
3 New Billion Dollar Crop in Popular Mechanics. 3 February 1938: 238-239.
4 Dewey, Lister Hoxley 1914. Yearbook of the U.S. Department of Agriculture. US Govt. Printing Office. Washington, DC: 313.
My article had for its objective, the separation of hemp facts from hemp fiction. That is
why I wanted to expose two commonly
repeated "hemp myths", namely that hemp core yields more dry matter than other crops, and that hemp core contains 77% cellulose. I am glad
that you now agree with me that
77% cellulose in the core is fiction rather than fact and that Dewey's claim may have been overstated.
In the article you have reacted to, I forgot to mention a third enduring hemp myth. Interestingly, in your attempt to explain why Dewey's hemp cultivar may have been more productive than modern varieties, you bring up this third myth. It can be summarized as "hemp bred for a low THC content is less productive and defenseless against pests". De Meijer (1994), in evaluating a collection of about 200 Cannabis accessions did not find associations between cannabinoid content and agronomic characteristics such as rate of stem elongation or occurrence of the fungus Botrytis cinerea. The Hungarian cultivar Kompolti Hybrid TC is similar to Dewey's cultivars: it is a hybrid of Chinese and European genotypes and relatively high in THC. In my experiments, its yield was not superior to that of other, low-THC Hungarian cultivars. So, until proven otherwise, I think the THC content of a hemp cultivar is irrelevant to its agronomic performance. I do, however, agree with you that a possible ecological role for the cannabinoids is an intriguing topic which merits further investigation (Pate 1994).
I would like to repeat that you should not take these criticisms personally. I, too, think that hemp is a marvelous and fascinating crop, but often read exaggerated statements made by some of the "hempsters". I feel the "hemp facts" are good enough and that this crop does not need "hemp fiction" to make it look better.
Hayo van der Werf
De Meijer, E. 1994. Diversity in Cannabis, Ph.D. Dissertation, Agricultural University of Wageningen, The Netherlands.
Pate, D.W. 1994. Chemical ecology of Cannabis, JIHA 1(2): 29, 32-37.