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Missouri Environment & Garden


Michele Warmund
University of Missouri
Plant Science & Technology
(573) 882-9632

Industrial Hemp: An Ancient Multipurpose Crop

Michele Warmund
University of Missouri
(573) 882-9632

Published: January 7, 2020

cannibus plants

Although industrial hemp (Cannabis sativa) is considered a new crop in Missouri, it is actually an ancient crop, which was harvested in China 8500 years ago. Fiber hemp was introduced to western Asia and Egypt, and then into Europe between 1000 and 2000 BCE. Many years later, hemp was imported into South America in 1545, and into North America at Port Royal, Acadia in 1606. Missouri was a major producer of fiber hemp from 1840 to 1860 due to the demand for sailcloth and rope. Thereafter, hemp was primarily grown in Kentucky until World War I. However, the Marijuana Tax Act all but ended fiber hemp production in 1938, except for a brief period from 1942 to 1945 when 400,000 acres were grown mostly for cloth and cordage.

Hemp is one of the oldest sources of textile fiber. The bast fibers in the phloem of the stem tissue ("bark") range from 0.2 to 1.6 inches long, while the stem core fibers, known as hurds, are shorter. Textiles made with bast fiber are strong and durable, with high tensile and wet strength. Thus, bast fibers were used extensively for rope, nets, canvas, sailcloth, and oakum for caulking on ships during the Age of Exploration. Fiber hemp was also valued for upholstery, bags, sacks, and tarpaulins during this time. Today, hemp is used in materials for clothing and footwear.

Until the early 1800's, paper was made primarily from hemp and flax. Thereafter, the development of cheap wood pulping methods for paper production was more economical than processing hemp and flax fibers. Today, specialty or premium hemp paper products made from bast fibers include art papers, tea bags, bank notes, technical filters, hygiene products, and cigarette paper.

Presently, hemp fiber is incorporated into plastic composites for molded car parts in Europe. However, Henry Ford used hemp and soybean to make durable car parts, such as trunk doors, in the 1940's. In car parts with fiber hemp, there is no splintering in accidents and it provides favorable mechanical and acoustical properties. Thus, hemp composites may have other uses in the manufacturing of bicycles, airplanes, and other types vehicles where lightweight parts, padding, or sound insulation is needed.

Fiber hemp is also used in building construction products. It is used for thermal insulation, fiberboard, and in cement and plaster to enhance the strength of building materials. For fiberboard, the short hurd fibers are used in composite wood products. The addition of hemp fibers into concrete also reduces shrinkage and cracking. Hemp hurds can also be chemically combined with other products to strengthen foundations, walls, floors and ceilings of structures, or to make tile-like products.

Outdoor products made from hemp fibers are called geotextiles or agricultural textiles. Hemp fiber netting or blankets are useful in preventing soil erosion and stabilizing new plantings during root development. Horticultural uses for hemp include biodegradable pots or rooting blocks for plants, or as twine or a biodegradable tying product to support plants and trees in landscapes, orchards, and vineyards to replace plastic ties. Hemp hurds are also useful for animal bedding and pet litter. Such products made from hurds are absorbent, dust-free (after manufacturing), biodegradable, and suitable for animals allergic to straw bedding.

Hulled hemp seed or cold-pressed hempseed oil is used for specialty food products, beverages, nutraceuticals, and cosmetics in North America. Due to the nutty flavor of hemp seeds, they have been added to several food products. Hemp oil is edible and may be useful in salad oils, but it is unsuitable for frying or baking, and has a short shelf-life as it becomes rancid quickly.

Although hemp food products containing less than 10 mg THC (tetrahydrocannabinol) per unit (serving or package) are available in Canada, the food use of hemp was banned in the United States in 2001 due to concern that consumption of hempseed products interferes with drug testing programs for marijuana usage. Also, U.S. Food and Drug Administration's lack of GRAS (generally recognized as safe) approval serves as a legal barrier to hemp food products.

As with any "new" crop, there are pitfalls for producers, including growing challenges, potential for overproduction, and a lack of secure markets. Producer experience in Canada indicates large profits from hemp are unfeasible unless one shares in value-added income. Finding a market before planting is a sound practice for any agricultural product.

For consumers, fiber hemp offers alternative products. Currently, market expansion of non-food hemp products is limited by crop availability and high costs associated with fiber extraction and manufacturing processes. However, with innovative solutions, technical challenges can be overcome.

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REVISED: January 7, 2020