Both hemp and cotton have been cultivated for thousands of years as fiber and food crops. Where they're grown, which crop is more environmentally friendly and which fiber is stronger are all answered below.
Hemp refers to varieties of the cannabis plant that are grown for industrial and commercial purposes such as clothing and health foods. It is similar to flax, jute, or ramie.
The hemp plant is tall and thin and grows from 5 to 15 feet in height. It is primarily grown in China as well as Europe, South America and North Korea. In just the past few years it has become legal to grow hemp in the United States.
Cotton is a fiber, feed and food crop that is native to tropical and subtropical regions around the world. It is used to manufacture a wide variety of products including apparel, sheets, towels, ropes, tarpaulins, tents, cooking oil, shortening, and salad dressing. The meal and hulls are used as livestock, poultry and fish feed and as fertilizer. Like hemp, cotton is a very versatile plant.
China is currently the world's largest cotton grower, India is second and the U.S. is third. Cotton is grown in 17 states, primarily in the South. Texas is the leading cotton producing state. Cotton is the most widely used natural fiber cloth for clothing. Because it is so widespread, cotton tends to be less expensive than hemp.
Hemp vs Cotton Fiber Properties
Hemp fabrics are stronger, more absorbent, more durable, and better insulating than cotton. Furthermore, they don’t stretch out of shape. This property makes hemp a perfect upholstery fabric because it can be pulled taut and remain taut throughout the life of the furniture. On the other hand, cotton is ideal for t-shirts, jeans, and other apparel where some stretch is desirable.
Cotton fabric is softer and more comfortable against the skin than hemp fabric. Hemp fiber has a rough feel to it in its natural spun state and is susceptible to fraying. Hemp also has a pronounced, naturally-occurring odor that some people don't care for.
Hemp fibers have a relatively large surface area and are very water absorbent. This allows the fiber to dye well and retain its color better than any other fabric including cotton or linen.
Cotton and Hemp Blends
Cotton blends very well with hemp. The hemp adds stability and strength to cotton, making the fabric stronger and slightly lowering its shrinkage. It also enhances dye retention. Note that both cotton and hemp will shrink when first washed.
History of Hemp Fibers
Historically, hemp (Cannabis sativa) was widely cultivated in the West as a fiber source for textiles and many other fiber products. After the prohibition of its psychoactive relative, marijuana, by the U.S. government in 1936, hemp all but vanished from Western markets and its market share was claimed by cotton and petroleum-derived synthetics. Since then, attitudes toward cannabis have evolved to be more tolerant and legislation has changed to accommodate its cultivation. Additionally, the environmentally taxing production processes of cotton and petroleum-derived synthetics have faced greater public scrutiny, with the looming threat of climate change. When compared to cotton, hemp is higher yielding, more sustainable and eco friendlier without sacrificing material performance. With these advantages, hemp shows great potential to make a return as the leading natural fiber in textiles.
Kentucky Hemp Harvest, - Popular Science Monthly Volume 54
History and Production of Hemp
The use of hemp can be traced back to 8000 BC in the Middle East and China where the fiber was used for textiles, ropes, and fishnets, the oil for
Hemp fibers are obtained from the bast of the hemp plant (sometimes referred to as “industrial hemp”), a specific strain of Cannabis Sativa used for fiber production. Depending on plot size, hemp may be harvested by hand or by machine. After harvest, the hemp stalks are left in the field to dry before being subject to decortication – the process by which the bast fiber is isolated and transformed into finished fiber. Decortication begins with retting, where water and microorganisms are used to break down the organic compounds that hold the bast fibers and the hurd together. Retting is followed by scutching, where the bast fiber is mechanically separated from the hurd. The resulting bundles of bast fiber are enzymatically stripped of any undesirable residuals (pectin, waxes, etc.) by a process called degumming. Finally, the degummed fiber is dried and run through an opener to further separate and parallelize the fibers in preparation for spinning.
Hemp Composition and Performance
Hemp’s fiber composition and morphology make it an ideal alternative to cotton and synthetics in many ways. Hemp’s most notable functional advantage over cotton is its superior tenacity. Like all cellulosic fibers, hemp fiber is comprised mostly of cellulose (60-70%), but also contains 15-20% hemicellulose (and ,5% of lignin, pectin, fats and waxes). Hemp fibers are uniquely long, relative to other natural fibers. The interspersing of branched hemicellulose fibers amongst cellulose fibers forms an interwoven cellulose-hemicellulose fiber network. The network formed by these long fibers serve as additional reinforcement to hemp spun yarn that is not observed in cotton spun yarn. This characteristic contributes to the strength of Ravenox natural hemp-blend ropes.
Hemp is also more absorbent and breathable than cotton and especially more so than petroleum-derived synthetics, due to the spaces within the cellulose-hemicellulose fiber network. This quality also better supports the dying of hemp, requiring fewer pre- and post-treatments relative to other natural fibers. Hemicellulose branching does make hemp rope less abrasion-resistant, but this quality also allows hemp to adopt a soft, brushed-fiber feel over time, a desirable characteristic in many textile applications. Another unique benefit of hemp is its natural abundance of cannabinoids (non-psychoactive) and terpenes, the antimicrobial activity of which is well documented.
Hemp’s low extensibility (percent of elongation) makes twisting hemp yarns a challenge for even the most experienced rope engineers. However, this quality makes hemp desirable for use in applications where “stretch” is a hindrance to product performance, such as boat sails and upholstery. Ravenox has mastered the art of twisting hemp through specific modifications of hemp fibers and formulation of proprietary blends with one or more other fiber types.
Sustainability and Cost of Hemp
Hemp is considered a carbon-negative crop, in that it sequesters more CO2 than it generates per harvest cycle. Additionally, hemp generates more fiber per acre in less time and with less water, compared to cotton. Hemp is markedly less fastidious than cotton and can grow in a wider range of climates and soil types. The hemp plant’s fast growth and dense canopy serves as its own weed suppressor, eliminating the need for herbicides. In short, industrial hemp production is hypothetically a more profitable fiber crop than cotton.
Unlike cotton, the hemp plant yields many raw materials that are valuable to other industries outside of textiles. For example, the hurds and tow fibers are used for building materials and biocomposites. Volkswagen, Mazda, Mercedes, among other automotive industry giants, use hemp biocomposites for the manufacture of interior components and/or body panels of their automobiles. In fact, a typical C-Class Mercedes Benz contains over 30 parts made from hemp and other natural fibers. Compared to their geotextile and petroleum-derived predecessors, hemp biocomposites demonstrate higher tensile strength and scratch resistance with a more ecofriendly life cycle. Additionally, hemp biocomposites are lighter weight, which reduces the fuel use and emissions of vehicles built from them.
The examples conferred herein, prove that hemp can fulfill many of the same roles as its cotton and petroleum-derived counterparts. This lends to the diversity of hemp’s usable material yield, which offers all hemp producers additional outlets for generating revenue.
The Cotton Plant
Cotton is a shrubby plant that is a member of the Mallow family. Its name refers to the cream-colored fluffy fibers surrounding small cottonseeds called a boll. The small, sticky seeds must be separated from the wool in order to process the cotton for spinning and weaving. De-seeded cotton is cleaned, carded (fibers aligned), spun, and woven into a fabric that is also referred to as cotton. Cotton is easily spun into yarn as the cotton fibers flatten, twist, and naturally interlock for spinning. Cotton fabric alone accounts for fully half of the fiber worn in the world. It is a comfortable choice for warm climates in that it easily absorbs skin moisture. Most of the cotton cultivated in the United States is a short-staple cotton that grows in the American South. Cotton is planted annually by using the seeds found within the downy wool. The states that primarily cultivate cotton are located in the "Cotton Belt," which runs east and west and includes parts of California, Alabama, Arkansas, Georgia, Arizona, Louisiana, Mississippi, Missouri, New Mexico, North Carolina, Oklahoma, South Carolina, Tennessee, and Texas, which alone produces nearly five million bales. Together, these states produce approximately 16 million bales a year, second only to China. Business revenue generated by cotton today is approximately $122.4 billion—the greatest revenue of any United States crop. The leading cotton-producing counties in North Carolina where Ravenox is headquartered, include Northampton, Halifax, Edgecombe, Martin, Bertie, Lenoir, Sampson, Pitt, Wilson and Wayne counties.
The cotton plant is a source for many important products other than fabric. Among the most important is cottonseed, which is pressed for cottonseed oil that is used in commercial products such as salad oils and snack foods, cosmetics, soap, candles, detergents, and paint. The hulls and meal are used for animal feed. Cotton is also a source for cellulose products, fertilizer, fuel, automobile tire cord, pressed paper, and cardboard.
Cotton - From Field to Bale
Every Spring, cottonseed is mechanically planted by machines in acreage that has been cleared by mechanical cultivators. The seed must be placed more shallowly in dusty, cool areas of the Cotton Belt, and more deeply in warmer areas. With good soil moisture and warm temperature at planting, seedlings usually emerge five to seven days after planting, with a full stand of cotton appearing after about 11 days.
Approximately six weeks after seedlings appear, "squares," or flower buds, begin to form. The buds mature for three weeks and then blossom into creamy yellow flowers, which turn pink, then red, and then fall off just three days after blossoming. After the flower falls away, a tiny ovary is left on the cotton plant. This ovary ripens and enlarges into a green pod called a cotton boll.
The boll matures in a period that ranges from 55 to 80 days. During this time, the football-shaped boll grows and moist fibers push the newly formed seeds outward. As the boll ripens, it remains green. Fibers continue to expand under the warm sun, with each fiber growing to its full length—about 2.5 in (6.4 cm)—during three weeks. For nearly six weeks, the fibers get thicker and layers of cellulose build up the cell walls. Ten weeks after flowers first appeared, fibers split the boll apart, and cream-colored cotton pushes forth. The moist fibers dry in the sun and the fibers collapse and twist together, looking like ribbon. Each boll contains three to five "cells," each having about seven seeds embedded in the fiber.
At this point the cotton plant is defoliated if it is to be machine harvested. Defoliation (removing the leaves) is often accomplished by spraying the plant with a chemical. It is important that leaves not be harvested with the fiber because they are considered "trash" and must be removed at some point. In addition, removing the leaves minimizes staining the fiber and eliminates a source of excess moisture. Some American crops are naturally defoliated by frost, but at least half of the crops must be defoliated with chemicals. Without defoliation, the cotton must be picked by hand, with laborers clearing out the leaves as they work.
Harvesting is done by machine in the United States, with a single machine replacing 50 hand-pickers. Two mechanical systems are used to harvest cotton. The picker system uses wind and guides to pull the cotton from the plant, often leaving behind the leaves and rest of the plant. The stripper system chops the plant and uses air to separate the trash from the cotton. Most American cotton is harvested using pickers. Pickers must be used after the dew dries in the morning and must conclude when dew begins to form again at the end of the day. Moisture detectors are used to ensure that the moisture content is no higher than 12%, or the cotton may not be harvested and stored successfully. Not all cotton reaches maturity at the same time, and harvesting may occur in waves, with a second and third picking.
How Cotton is Processed in Factories
Once the cotton is harvested using a cotton picker and is packed into large containers making what is called a module. These modules are filled with debris and are shipped off to a factory or the Cotton Gin where the cotton can be cleaned. All sticks, burrs, and lingering debris are removed and the cotton moves through the process of being cleaned. The cotton is dried and continues the cleaning process until the lint is separated from the seeds, and is packed for shipping to a factory that will continue to process the raw cotton and turning it into useful cotton yarn.
Cotton Byproducts and Waste
There is much discussion regarding the amount of chemicals used in cotton cultivation. Currently, it is estimated that growers use, on average, 5.3 oz (151 g) of chemicals to produce one pound of processed cotton. Cotton cultivation is responsible for 25% of all chemical pesticides used on American crops. Unfortunately, cotton attracts many pests (most notably the boll weevil) and is prone to a number of rots and spotting, and chemicals are used to keep these under control. There are concerns about wildlife poisoning and poisons that remain in the soil long after cotton is no longer grown (although no heavy metals are used in the chemicals). As a result, some farmers have turned to organic cotton growing. Organic farming utilizes biological control to rid cotton of pests and alters planting patterns in specific ways to reduce fungicide use. While this method of cultivation is possible, an organically grown crop generally yields less usable cotton. This means an organic farmer must purchase, plant, and harvest more acreage to yield enough processed cotton to make the crop lucrative, or reduce costs in other ways to turn a profit. Increasingly, state university extension services are working with cotton farmers to reduce chemical use by employing certain aspects of biological control in order to reduce toxins that remain in the land and flow into water systems.
Cotton is a very water and pesticide intensive plant to grow. It has a much higher environmental cost than hemp which requires fewer pesticides or fertilizers and no herbicides. Hemp requires much less water, grows very quickly (70 to 110 days), and uses minimal nutrients from the soil. Hemp plant roots aerate the soil, leaving it rich for future crops. Hemp will produce 1500 pounds of fiber per acre, whereas cotton will produce only 500 pounds per acre!
Hemp and the Future of Textiles
Hemp is a stronger, more durable, beneficial, and important part of environmental sustainability and it's also a crucial part of the healing of our planet because hemp enhances the microbial content in the soil where it grows. Hemp also stops weeds from sprouting near it. Its thick roots prevent soil decay.
This super plant can sustain our planet with many of the materials that we need daily while conserving the well being of our planet much more than cotton ever could.