Preliminary work in Germany (noted in Karus and Leson 1994) suggested that hemp could be grown on soils contaminated with heavy metals, while the fiber remained virtually free of the metals. Kozlowski et al. (1995) observed that hemp grew very well on copper-contaminated soil in Poland (although seeds absorbed high levels of copper). Baraniecki (1997) found similar results. Mölleken et al. (1997) studied effects of high concentration of salts of copper, chromium, and zinc on hemp, and demonstrated that some hemp cultivars have potential application to growth in contaminated soils. It would seem unwise to grow hemp as an oilseed on contaminated soils, but such a habitat might be suitable for a fiber or biomass crop. The possibility of using hemp for bioremediation deserves additional study.
The high lipid-solubility of cannabinoids results in their persisting in the body for long periods of time.[131] Even after a single administration of THC, detectable levels of THC can be found in the body for weeks or longer (depending on the amount administered and the sensitivity of the assessment method).[131] A number of investigators have suggested that this is an important factor in marijuana's effects, perhaps because cannabinoids may accumulate in the body, particularly in the lipid membranes of neurons.[132]
Cannabis research suggests medical marijuana could become an effective treatment for diabetic neuropathy. Diabetic neuropathy is a debilitating and sometimes fatal condition caused by diabetes. Diabetics suffer from high blood sugar due to insulin resistance, and this damages nerve cells in the body, causing severe pain. Patients who consumed THC as part of a study found they experienced less pain. Findings are not definitive, however, and further research into cannabis as a treatment for diabetes and associated symptoms is required.
It is clear that there is a culture of idealistic believers in hemp in North America, and that there is great determination to establish the industry. As history has demonstrated, unbridled enthusiasm for largely untested new crops touted as gold mines sometimes leads to disaster. The attempt to raise silk in the US is probably the most egregious example. In 1826 a Congressional report that recommended the preparation of a practical manual on the industry resulted in a contagious desire to plant mulberries for silk production, with the eventual collapse of the industry, the loss of fortunes, and a legacy of “Mulberry Streets” in the US (Chapter 2, Bailey 1898). In the early 1980s in Minnesota, Jerusalem artichoke was touted as a fuel, a feed, a food, and a sugar crop. Unfortunately there was no market for the new “wonder crop” and hundreds of farmers lost about $20 million (Paarlberg 1990). The level of “hype” associated with industrial hemp is far more than has been observed before for other new crops (Pinfold Consulting 1998). Probably more so than any plant in living memory, hemp attracts people to attempt its cultivation without first acquiring a realistic appreciation of the possible pitfalls. American presidents George Washington and Thomas Jefferson encouraged the cultivation of hemp, but both lost money trying to grow it. Sadly in Canada in 1999 numerous farmers contracted to grow half of Canada’s crop area for hemp for the American-based Consolidated Growers and Processors, and with the collapse of the firm were left holding very large amounts of unmarketable grain and baled hemp straw. This has represented a most untimely setback for a fledgling industry, but at least has had a sobering effect on investing in hemp. In this section we emphasize why producers should exercise caution before getting into hemp.

Quality is a particular concern, because cannabis plants easily soak up heavy metals from pesticides and other contaminants, Marcu says. If you are buying online, look for a company that documents how it tests its products. (If the website doesn’t indicate this, call and ask.) “Buying from a reputable manufacturer is crucial, because it matters how the plant is cultivated and processed,” Dr. Maroon says. One clue that a company is cutting corners: too low a cost. Good CBD is pricey—a bottle of high-quality capsules is sold in Cohen’s office for $140. But for many, it’s worth the money. Roth spent $60 on her tiny bottle. But when her energy returned the day she started taking CBD, she decided that was a small price to pay.
For profitable hemp farming, particularly deep, humus-rich, nutrient-rich soil with controlled water flow is preferable. Waterlogged acidic, compressed or extremely light (sandy) soils primarily affect the early development of plants.[citation needed] Steep and high altitudes of more than 400 m above sea level are best avoided. Hemp is relatively insensitive to cold temperatures and can withstand frost down to −5 °C.[citation needed] Seeds can germinate down to 1–3 °C.[citation needed] Hemp needs a lot of heat, so earlier varieties come to maturation. The water requirement is 300–500 l/kg dry matter.[citation needed] This is around 1/14th that of cotton, which takes between 7,000 and 29,000 l/kg, according to WWF.[citation needed] Roots can grow up to 3 feet into the soil and use water from deeper soil layers.
The reason so many people are interested in cannabis products that don’t make them high, proponents say, is that CBD helps with everything from pain and nausea to rheumatoid arthritis, cancer, Crohn’s disease, and dementia. CBD is anti-inflammatory, anti-anxiety, antibacterial, immunosuppressive, and more, says Joseph Cohen, D.O., a cannabis doctor in Boulder, CO.
Approximately 65% of sub-Saharan Africa’s agricultural land is degraded, according to data collected in 2015, resulting in food insecurity and a declining economy in a region where the agricultural industry employs more than half of the total labor force. Hemp’s soil nutrient replenishing properties could be the key to reviving crop production, providing a novel food source (hemp seeds) and boosting the agro-based economies of South Africa and other hemp-cultivating sub-Saharan countries.
^ Jump up to: a b c d Campos AC, Moreira FA, Gomes FV, Del Bel EA, Guimarães FS (December 2012). "Multiple mechanisms involved in the large-spectrum therapeutic potential of cannabidiol in psychiatric disorders". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences (Review). 367 (1607): 3364–78. doi:10.1098/rstb.2011.0389. PMC 3481531. PMID 23108553.
As noted above, hemp seed cake makes an excellent feed for animals. However, feeding entire plants is another matter, because the leaves are covered with the resin-producing glands. While deer, groundhogs, rabbits, and other mammals will nibble on hemp plants, mammals generally do not choose to eat hemp. Jain and Arora (1988) fed narcotic Cannabis refuse to cattle, and found that the animals “suffered variable degrees of depression and revealed incoordination in movement.” By contrast, Letniak et al. (2000) conducted an experimental trial of hemp as silage. No significant differences were found between yield of the hemp and of barley/oat silage fed to heifers, suggesting that fermenting hemp plants reduces possible harmful constituents.

"Industrial hemp" means a fiber or oilseed crop, or both, that is limited to types of the plant Cannabis sativa L. having no more than three-tenths of 1 percent tetrahydrocannabinol (THC) contained in the dried flowering tops, whether growing or not; the seeds of the plant; the resin extracted from any part of the plant; and every compound, manufacture, salt, derivative, mixture, or preparation of the plant, its seeds or resin produced therefrom.
Since the beginning of the 20th century, most countries have enacted laws against the cultivation, possession or transfer of cannabis.[209] These laws have impacted adversely on cannabis cultivation for non-recreational purposes, but there are many regions where handling of cannabis is legal or licensed. Many jurisdictions have lessened the penalties for possession of small quantities of cannabis so that it is punished by confiscation and sometimes a fine, rather than imprisonment, focusing more on those who traffic the drug on the black market.
This law provides a framework for commercial industrial hemp production in Montana following approval by the federal government. Provisions added to the 2014 Farm Bill (Section 7606) defined industrial hemp under federal law and recognized state agricultural departments' authority to develop research pilot programs to study the growth, cultivation, and/or marketing of industrial hemp.
Cannabis is mostly used for recreation or as a medicinal drug, although it may also be used for spiritual purposes. In 2013, between 128 and 232 million people used cannabis (2.7% to 4.9% of the global population between the ages of 15 and 65).[28] It is the most commonly used illegal drug both in the world and the United States.[21][28] The countries with the highest use among adults as of 2018 are Zambia, the United States, Canada, and Nigeria.[29] In 2016, 51% of people in the United States had ever used cannabis.[30] About 12% had used it in the past year, and 7.3% had used it in the past month.[31]
Although cannabis as a drug and industrial hemp both derive from the species Cannabis sativa and contain the psychoactive component tetrahydrocannabinol (THC), they are distinct strains with unique phytochemical compositions and uses.[6] Hemp has lower concentrations of THC and higher concentrations of cannabidiol (CBD), which decreases or eliminates its psychoactive effects.[6] The legality of industrial hemp varies widely between countries. Some governments regulate the concentration of THC and permit only hemp that is bred with an especially low THC content.[7][8]