Sarah Kessler, writing for OneZero:
All cannabis plants, including hemp, have some amount of the psychoactive chemical compound THC. Cannabis sold legally as marijuana may have as much as 20% THC on a dry-weight basis, while farmers growing hemp for textiles, food, or CBD are required by law to meet a much lower limit of 0.3%. Neither a 0.3% THC cannabis plant nor a 0.4% THC cannabis plant will get you any higher than smoking grass from your lawn, but in the eyes of the law, that tiny tenth of a percent makes all the difference.
To comply with federal rules, states must ensure the “disposal” of a hemp crop that tests over the 0.3% limit, a process that usually involves plowing it down or burning it on-site. A draft of new hemp-growing guidelines proposed by the USDA, the first such guidelines from the federal government, establishes a margin of error for meeting the THC limit, but is strict about the consequences of failing the test. If the rules go into effect as written, farmers with what the industry calls “hot” crops that exceed the 0.3% limit will be responsible for paying an estimated $200 per acre to destroy their own crops, on top of losing the commercial value of the plants. This is true even if the grower is operating in a state that has legalized recreational marijuana, which requires a different type of license. […]
Meanwhile, since both CBD and THC in a plant increase over time as it grows, most farmers who buy even otherwise high-quality seed are still caught playing a game of chicken: They want to leave their plants in the field long enough to maximize CBD. But if they wait too long to harvest, they’ll end up with too much THC — and a crop that has to be destroyed.
This whole situation is completely bonkers. There’s no scientific reason to have hemp defined exclusively as “cannabis containing less than 0.3% THC, and it doesn’t look like the definition is going to change anytime soon. However, farmers shouldn’t lose all hope:
But as scientists develop a better understanding of hemp, science could help farmers sidestep politics. Breeders will develop varieties with specific traits, certification process will help farmers predict results, and eventually the results from low-THC certified varieties will be so well-known that states won’t even need to test plants themselves. “I think that’s possible,” Steenstra says. “But it will take some time. “