"Industrial Hemp,Agronomy and Ultilization"

There are increased interests in growing grain and fiber hemp (Cannabis sativa L.) as well as in large-scale hemp products. Cannabis has been grown/ utilized for thousands of years as a fiber, grain, and medicinal plant. 

However, the strict control of cannabis cultivation to combat illegal use, the spread of new yarns and oilseeds, and the advent of cheap synthetic fibers caused a decreased/eliminated hemp production

Hemp has a long history of being used for fiber, grain, and medicinal purposes, but its cultivation has been strictly controlled due to concerns about illegal drug use, competition from synthetic fibers, and bans in many countries.

However, with the legalization of hemp in the USA through the 2014 and 2018 Farm Bill, research programs have been launched by universities to explore its potential. Hemp has the advantage of being a versatile crop that can be used for multiple purposes, creating opportunities for the market to value hemp products.

This paper, published on MDPI Open Access Jurnals, highlights that hemp has the potential to be a sustainable and environmentally friendly crop, with its ability to absorb heavy metals, sequester carbon, and suppress weeds without the use of pesticides. The paper aims to examine the historical and recent literature on hemp agronomy and utilization, focusing on industrial hemp for grain and fiber production.

-Introduction...

Hemp is a versatile plant with a wide range of ecological, agronomical, and pharmaceutical properties, making it a useful raw material for various conventional and advanced industrial products. Hemp has been traditionally grown for fiber and grain, but it has a wide range of current and future applications in nutrition, energy, textiles, healthcare, and industrial goods. Hemp is classified as "industrial hemp" in most countries, with the concentration of delta-9 tetrahydrocannabinol (THC) being a regulatory factor.

Hemp has several environmental advantages, including its potential for phytoremediation of polluted soils, its use as a pesticide-free crop that can suppress weed growth, and its ability to absorb and store carbon dioxide (CO2) through photosynthesis. Hemp can also be used for biochar production, which can improve soil properties and mitigate greenhouse gas emissions.

Hemp is considered to be more energy effective due to its weed control, reduced pesticide usage, and soil-health-enhancing characteristics. Hemp grows in a wide range of environments, with different ecotypes performing better in particular areas of growth. Hemp has specific environmental requirements such as temperature, soil type, and pH value for optimal growth.

Overall, hemp has the potential to be a sustainable and environmentally friendly crop with multiple uses and applications in various industries.

-Hemp Taxonomy...

The classification of Cannabis, Humulus, and eight other genera (Celtis, Pteroceltis, Aphananthe, Chaetachme, Gironniera, Lozanella, Trema, and Parasponia) has been reclassified as the Cannabaceae family. Hemp taxonomy has been a subject of debate at the genus level due to variations in gender expression and phenotypic characteristics influenced by the environment.

Hemp is primarily a dioecious or infrequently monoecious annual herb with a variable height ranging from 0.2 to 6 meters, depending on the variety and environment. Female plants are generally more robust compared to males, which are taller and slender. The leaves of hemp plants have palmar composite morphology with 3 to 13 leaflets basally and 1 to 3 leaflets apically, arranged alternately or oppositely on the stem.

Male flowers develop as loose floral bunches with few leaves at the end of the central stem, while female flowers are borne on racemes at the apex of the stem. Male flowers have five green-yellow sepals enclosing closely packed stamens with tiny anthers, while female flowers have two pistils and a single seed compartment. Hemp seeds are spherical or ovoid in shape, measuring 3-5 mm in length depending on the cultivar.

The division into types and varieties of hemp is based on the THC content, with weakly intoxicant Cannabis sativa ssp. sativa (THC < 0.3%) including cultivated and naturalized weedy or wild hemp, and strongly intoxicant Cannabis sativa ssp. indica (THC > 0.3%) including domesticated and wild varieties.

-Fiber and Grain Uses...

Hemp has been used for centuries to make fabrics, cordage, yarns, carpets, and cloth due to its strength and adaptability. Hemp fibers are stronger than other natural fibers such as cotton, linen, and nettle, and are also water-resistant. Hemp was widely used for garments until the cotton industry became dominant. Hemp fibers are currently being used in the textile industry to create a variety of fabrics including clothing, jeans, sportswear, bags, hats, pillowcases, blankets, shoes, and socks.

Hemp is also used to make jewelry and other ornaments. Hemp fibers can be blended with other materials like cotton or linen to create hybrid fabrics with specific textures and functions. Hemp is also used as a sustainable fabric for upholstery and furniture, including chairs, tables, fashion accessories, mirrors, wall decor, and ornamental items.

Hemp has also been used to make paper for a long time, with ancient China using hemp fibers to make paper scrolls. Hemp paper was used to write the U.S. Constitution and the earliest copies of the Bible. Hemp paper is stronger, more durable, and less likely to yellow compared to paper made from wood. Hemp fibers have high cellulose content, making them ideal for papermaking. Hemp paper is recyclable and can be reused multiple times, making it more sustainable than regular pulpwood paper.

Hemp can be used to produce specialized papers for writing, printing, archival, protective, greasy papers, membrane filters, coffee and tea bags, handcrafted papers, bible sheets, and specialist artistic documents. Hemp can also help prevent deforestation, as it can produce as much paper in a 20-year cycle as trees on a much larger area of land.

Hemp can also be used in construction as building materials. Hemp fibers can be used in insulation materials, benefiting from their mechanical strength and ecological advantages. The low density and insulating qualities of hemp fibers make them ideal for use in light and ultra-light concrete and mortar, used in plastering, paving, wall building, and roof insulation.

Hemp hurds, the wooden core of the hemp stalk, can also be used as insulating material in construction. However, due to limited hemp production, these uses are not yet fully developed. Hemp-based materials can also be used to create commercial items that mimic concrete, wood, and plastic with different densities.

Hemp biomass, including low-grade fibers or hurds, can be utilized as a feedstock for various forms of energy, heat, and fuel. One common application is to use hemp biomass pellets as a direct heat source in residential wood stoves, providing heat for homes. This can be done on a larger scale for power generation using generators if the biomass is transformed into charcoal. This "green" power generation method could potentially replace coal combustion in co-generation processes that currently rely on forestry and farm waste as feedstock.

In addition to direct combustion, hemp biomass can also be processed through various methods such as fermentation, pyrolysis, and destructive distillation to produce methanol, ethanol, or gasoline. These processes involve breaking down the biomass into its constituent parts and converting them into fuel products that can be used in various applications.

However, it's important to note that the current scale and valuation of the hemp industry may not make these applications of hemp biomass economically feasible. Further research, development, and investment in hemp biomass processing technologies, as well as supportive policies and regulations, may be needed to fully realize the potential of hemp as a source of energy, heat, and fuel. Nevertheless, the use of hemp biomass as a renewable and sustainable feedstock for energy production holds promise and could contribute to the transition towards more environmentally friendly and sustainable energy sources.

-Conclusions and Future Perspectives...

Hemp has gained significant attention in recent years due to its potential as a sustainable fiber crop, food source, medicinal plant, and biofuel. Hemp fibers currently make up a small fraction of textiles produced worldwide, with cotton still dominating the market. However, innovative techniques have allowed for the use of hemp in building materials, bioenergy, and industrial paper, as well as the development of hemp derivative products to replace petrochemicals. As demand for nutrient-dense hemp seeds increases, there is great potential for the hemp seed industry.

In order to fully realize the potential of hemp, there are several key factors that need to be addressed. First, there is a need to develop production technologies, harvesting methods, and processing equipment to increase the production area for industrial hemp. Additionally, market questions need to be answered through modern research, guidelines, and scientific projections, considering the ban on hemp production that lasted for many decades. Legislation should also progress to remove remaining hurdles and clarify and adapt laws on psychoactive substances and food safety to not impede hemp utilization. Government support in the form of subsidies, similar to those provided to other crop producers, can also help hemp producers.

Furthermore, the understanding and support of all these aspects would contribute to the development of a wider breadth of research, resulting in more robust knowledge and improved utilization of hemp products by human societies. It is important to recognize the potential of hemp as a versatile and sustainable crop and work towards creating an environment that promotes its growth and utilization in various industries.