Cannabis requires more water than staple crops, the researchers say


Cannabis producers have long believed that marijuana and hemp consumed less water than other staple crops, making it an ideal alternative for drought-stricken or arid growing regions.

However, new research shows that this is not necessarily the case and, in many cases, cannabis can require more water than even some conventional crops.

a study review the environmental impacts of cannabis cultivation shows that growing the plant both indoors and outdoors requires a lot of water and that the high demand for water ultimately leads to pollution and water diversion.

Three Illinois State University researchers looked at the literature on cannabis cultivation and its environmental impact on water, air, soil, energy use, and carbon footprint.

They found that the demand for water for growing cannabis typically exceeds that of staple crops by nearly double.

On average, the researchers found, a cannabis plant consumes about 22.7 liters, or 6 gallons, of water per day during the growing season, which typically lasts 150 days from June to October.

By comparison, wine grape, which is an irrigated crop produced in the same region as many outdoor cannabis crops in Northern California, uses an estimated 12.64 liters of water per day.

According to a 2019 survey in Humboldt County:

  • Water consumption for outdoor cannabis growing in Northern California is 5.5 gallons per day per plant in August and 5.1 gallons per day per plant in September.
  • Indoor growing used 2.5 gallons per day per plant in August and 2.8 gallons per day per plant in September.

Irrigated agriculture in California is considered the largest consumer of water, accounting for 70% to 80% of stored surface water.

As water scarcity continues to be a problem due to agricultural demand, population growth and climate change, the increase in water needs for cannabis crops will challenge the marijuana and hemp industries while weighing on the environment, the researchers concluded.

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“A little more nuanced”

Average daily water use and requirements for cannabis crops will certainly vary based on growing region, soil properties, climate and crop types, the researchers noted, but in general cannabis should be considered. a highly utilized aquatic plant.

Cannabis geneticist and breeder Brian Campbell agrees that cannabis is by no means a “miracle plant” that can be magically produced with little or no water, but it’s more complicated than that, he said. MJBizDaily.

Currently a plant grower for Charlotte’s Web in Boulder, Colorado, Campbell conducted his research on the use of cannabis water while pursuing his Ph.D. at Colorado State University.

Studies are still ongoing to measure exactly how much water cannabis uses, but they are highly variable due to the many different end uses for crops like hemp, Campbell said.

“For example, when you plant hemp for fiber, you plant it in a completely different way than you plant when you grow for CBD, and if you grow for oilseed, you plant in a different way and use different varieties,” he said. said.

Fiber varieties can be water-intensive because seeds can be planted tightly together and then grow several feet for biomass, while shorter seed varieties often finish 40 days earlier than fiber varieties.

Then there are the cannabinoid varieties, which are spaced apart and less dense but grown to larger sizes to maximize biomass.

“So there are all these different styles of crop management that go hand in hand with what you’re trying to produce,” Campbell said.

This differs from researchers’ comparisons of non-specific, outdoor and indoor cannabis which did not include the life stage of the crops, for example.

“There are huge differences in the amount of water you will use during the life stages of plants, as well as where you grow them,” Campbell said.

“I think it’s a little more nuanced than one (crop) is better than the other.”

Plus, there’s a big difference between simply growing a crop to survive and feeding it water and nutrients to maximize yield and top-notch performance, Campbell said.

Growing high-THC cannabis uses more water per plant because there is a strong push in the market for quality characteristics and limiting water can damage some of these parameters, he added. So it could use more or less of hemp depending on how densely the crops are planted, as well as the size and varieties in production.

Compete with Big Ag

Hemp has great potential to compete with crops like corn, cotton, and soybeans, but as the industrial hemp supply chain is built, those crops aren’t going anywhere, Campbell said.

And, like cannabis, they all perform and yield better with more water than with less.

“There are a lot of people pushing to build infrastructure and gain a foothold in these (industrial) markets,” he said, but when you look at the CBD market, there is no other crop to compete with. “

Campbell added that he is optimistic about diversifying the hemp market and building that industrial infrastructure, but there is still a long way to go and having false expectations is useless.

Marijuana and hemp are crops that will need to be managed like other crops, with rotation needs, water and fertilizer needs, he points out.

“People are still composing it because a lot of those basic agronomic things weren’t done during Prohibition when it was on every other crop, so we’re still learning where the sweet spots are,” Campbell said.

“When you’re not exactly sure how much fertilizer or water you will need, you will tend to go a little higher rather than a little under, as it will make a more productive crop and you won’t be hit on yield.”

Laura Drotleff can be reached at [email protected].


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