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Industrial Hemp: An Overview

Industrial Hemp is an ancient crop of great promise to the 'modern' world. It is a high yield crop which produces strong and versatile fibres and highly nutritious seed. Unlike the vast majority of commercial crops it requires neither pesticides nor herbicides to thrive.

Because of its association with marijuana, the cultivation of hemp has been prohibited in many countries for more than half a century. Recently, however, many governments have realized that the hysteria which lead to hemp's prohibition was unfounded, and hemp has been relegalized in many industrial countries, including most of Europe and Canada, over the past few years (the notable exception is the United States where government paranoia still runs high).

Still many of the claims made by pro-hemp enthusiasts are clearly overstated (for a more detailed account check out Hemp facts and hemp fiction by Hayo van der Werf). It is our belief that hemp will not single-handedly save the planet, but that it is a valuable crop with many potential uses which is ideally suited to a more sustainable approach to development.

Industrial Hemp

Hemp is an annual herbaceous plant of the species cannabis sativa, meaning ‘useful hemp’. It is a high yield commercial fibre crop which flourishes in areas with temperate climates, such as Canada. Hemp grows successfully at a density of up to 150 plants per square meter, and reaches a height of two to five meters in a three month growing season.

Every part of the hemp plant can be used commercially. The stalk of the hemp plant is harvested for its fibers. The fiber length and the content of cellulose and lignin are important quality parameters for raw material used in the cordage, textile, paper and fiberboard industries. The seeds are valuable for their nutritional properties, being high in protein and essential fatty acids.

Hemp vs. Marijuana

The flowering tops and to a lesser extent, the leaves of the Cannabis Sativa plant contain delta-9 tetrahydrocannabinol (THC). This chemical substance (one of many 'cannabinoids' found in varying degrees in cannabis sativa) gives marijuana its psychoactive properties. Generally Cannabis Sativa strains with a THC concentration of less than 0.3 % are classified as low-THC or ‘fibre’ hemp. At this low concentration, the psychoactive properties of the hemp plant are nonexistent. Marijuana, on the other hand has an average potency of 5-15% THC. In any Cannabis plant, no THC is to be found either in the stalk or the seeds.

For a detailed discussion of THC and CBD the other principal cannabinoid found in Cannabis Hemp, please see "A Discussion of Cannabis Cannabinoids -THC & CBD" by Gordon Scheifele & Peter Dragula.

Bast Fibers

Hemp has traditionally been grown for its valuable and versatile high quality (primary bast) fibers. The production of these fibers has traditionally been a very labour intensive process. After harvesting, the hemp stalks are soaked with water to initiate a process of retting (the decompositional separation of the bark-like bast fibers from the inner woody core). After the retting process, the plants are dried and then the fiber must be separated from the hurds, shaken out, and cleaned. Once separated, the bast fibers are ready for further processing: additional refining for spinning and weaving into textiles, or for pulping into high quality pulp. Because of their high tensile strength, bast fibers are ideal for such specialized paper products as: tea bags, industrial filters, currency paper, or cigarette paper.

Bast fibers account for 20-30% of the stalk (depending primarily on seed variety, and planting density) and come in two varieties:

primary bast fibers (approx. 70%) which are long, high in cellulose and low in lignin. These fibers are the most valuable part of the stalk, and are generally considered to be among the strongest natural fibers known to mankind.
secondary bast fibers (approx. 30%) which are medium length and higher in lignin are less valuable and become more prevalent when the hemp plants are grown less densely (thereby competing less for light), and thus grow shorter, fatter stalks.

Hemp Hurds

The hurds are the short fibred inner woody core of the hemp plant which comprises 70-80% of the stalk. They are composed of libriform fibers which are high in lignin. The hurds are essentially the by-product of the process of extracting bast fiber from the hemp stalks, and were traditionally considered waste. Though the fibers are shorter, the lignin content of hurds is similar to wood, so there are opportunities for using the hurds for tissue or newsprint pulp. Hurds can also be used to produce a wide range of products including animal bedding and building materials.

Hemp Seeds

Hemp seeds (grain) are also a potentially valuable commodity. The seeds have exceptional nutritional value. They are second only to soybeans as a source of complete vegetable protein and hemp seeds contain all 8 essential amino acids in the correct proportions humans require. Hemp seeds also contain 30-35% oil by weight. Hemp seed oil is approximately 80% polyunsaturated essential fatty acids (EFA’s). Furthermore, the proportion of these oils in hemp seeds most closely match the ratios which have been determined to be most beneficial to human nutrition.

Although hemp seed oil is very healthy, its high proportion of polyunsaturated fats also makes hemp seed oil somewhat unstable and so subject to fairly rapid rancidity unless preserved. Hemp seed oil can be extracted or expressed and used in cooking, or industrial uses such as paints, varnishes, detergents, cosmetics, and lubrication. The left over seed cake is a rich source of protein which can be ground into flour.

Hemp and the Environment

In both its cultivation and uses, hemp is considered an exceptionally environmentally friendly crop.

Hemp requires little or no pesticides as it is naturally pest resistant, as has been known to reduce pests in future crops, when grown in rotation (soybean cyst nematode populations have been documented to have been suppressed by 80% when grown after hemp)

Hemp is also a natural herbicide known for its ability to smother weeds when grown at a density suitable for producing high quality bast fiber.

Hemp also has a lower net nutrient requirement than other common farm crops, since it can return 60-70% of the nutrients it takes from the soil when dried in the field. However, prior to the nutrient recycling, hemp extracts more nutrients per hectare than grain crops due to its fast biomass production.

Its deep root system is also very beneficial as it is effective in preventing erosion, removing toxins, providing a disease break, and helping the soil structure by aerating the soil for future crops, when it’s grown in rotation with other crops.

Hemp is also a particularly high yield fibre crop. In fact, an acre of hemp produces more biomass than most other crops. As a result hemp can be used effectively in many applications as an alternative to wood or fossil fuels. For example, hemp can be used as a renewable, low polluting source of biomass fuel, or hemp can be used to make paper and fibreboard.

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