The seeds are sown with grain drills or other conventional seeding equipment to a depth of 1.27 to 2.54 cm. Greater seeding depths result in increased weed competition. Nitrogen should not be placed with the seed, but phosphate may be tolerated. The soil should have available 89 to 135 kg/ha of nitrogen, 46 kg/ha phosphorus, 67 kg/ha potassium, and 17 kg/ha sulfur. Organic fertilizers such as manure are one of the best methods of weed control.
The other notable difference between hemp and CBD oil is the amount of Tetrahydrocannabinol (THC), one of the 13 components found in cannabis. Hemp oil has low levels of THC (less than 25 parts in a million) while CBD can have as much as 15% CBD. In fact, one of the considerations to make when buying either of the oils is to check the amount of THC in the product as indicated on the label.
The etymology is uncertain but there appears to be no common Proto-Indo-European source for the various forms of the word; the Greek term kánnabis is the oldest attested form, which may have been borrowed from an earlier Scythian or Thracian word. Then it appears to have been borrowed into Latin, and separately into Slavic and from there into Baltic, Finnish, and Germanic languages. Following Grimm's law, the "k" would have changed to "h" with the first Germanic sound shift, after which it may have been adapted into the Old English form, hænep. However, this theory assumes that hemp was not widely spread among different societies until after it was already being used as a psychoactive drug, which Adams and Mallory (1997) believe to be unlikely based on archaeological evidence. Barber (1991) however, argued that the spread of the name "kannabis" was due to its historically more recent drug use, starting from the south, around Iran, whereas non-THC varieties of hemp are older and prehistoric. Another possible source of origin is Assyrian qunnabu, which was the name for a source of oil, fiber, and medicine in the 1st millennium BC.
The National Cancer Institute details several studies into the anti-tumor effects of CBD. One study in mice and rats suggest CBDs “may have a protective effect against the development of certain types of tumors.” CBDs may do this by inducing tumor cell death, inhibiting cancer cell growth, and by controlling and inhibiting the spread of cancer cells.
The results “suggest CBD to be a potential treatment for nicotine addiction,” the study authors wrote—but they also admit that their findings are preliminary. Ryan Vandrey, PhD, a cannabis researcher and associate professor of psychiatry at Johns Hopkins University (who was not involved in the 2013 study), agrees that larger, longer-term studies are needed to know if CBD might be helpful for smokers looking to kick the habit.