What is the impact of cannabis cultivation on the environment?

In recent years, scientific research has multiplied in order to better understand cannabis and its effects on humans. Recently, new research has looked into the environmental impact of its cultivation.

The cultivation of cannabis would have a strong environmental impact.

This analysis was conducted by Zhonghua Zheng, Kelsey Fiddes and Liangcheng Yang, all researchers in the Department of Health Sciences Environmental Health and Sustainability Program at Illinois State University.

As scientists remind us, cultivation methods have an inevitable influence on the environment to varying degrees. If outdoor cultivation is the traditional and original method for cannabis, it is directly subject to various problems such as weather conditions or parasites. In addition, poor soil or water management can have disastrous results on the harvest.

In order to overcome some of these problems, indoor or greenhouse cultivation presents itself as an attractive alternative. However, this is much more expensive, especially in terms of energy.

In the wake of the legalization and new acceptance of cannabis around the world, the research team wanted to analyze all the literature currently available concerning the cultivation of cannabis, with the aim of better understanding its potential environmental impacts. A study that addresses the effects of this culture on air, water, soil, but also looks at energy consumption and the carbon footprint it represents.

Cannabis, a water-hungry plant

Cannabis plant with wet leaves

With enormous water needs, does cannabis have a future?

Regarding the water demand of cannabis during its cultivation, the scientists note that this is almost 2 times higher to that of corn, soybeans, wheat, or even grapes. Recalling that in California, agriculture is considered the largest consumer of water and that the demand continues to grow for this resource in a context of population growth and climate change, the future could look bleak for cannabis, a plant whose water needs exceed those of other plants.

The other issue raised by science regarding the use of water for growing cannabis concerns a common practice in agriculture called diversion. This practice involves withdrawing or transferring water from one watershed to another to meet irrigation needs.

If this practice alleviates the problem of water scarcity for growing hemp, it would create new ones. For example, in a 2015 study that looked at the impact of cannabis cultivation on 4 watersheds in northwestern California, it was revealed that the amount of water needed to this culture exceeded the flow of the rivers during their low water period (the period of the lowering of the river). A fact that led to the reduction of the flow of these rivers as well as their drying up.

The researchers recommend normalizing the cultivation of cannabis.

Water pollution problems should also be highlighted, in particular because of the nutritional needs of the cannabis plant (nitrogen, phosphorus or even potassium).

Pollution further accentuated by the use of pesticides applied in the fields, the residues of which can find their way into water which is then found in the aquatic environment, thus representing a danger to its environment.

Water polluted in this way could also, due to heavy rainfall or excessive irrigation, end up in runoff or groundwater, thus representing a danger for other crops, but also for humans throughout the world. food chain.

For scientists, it is today “vital to get all growers on the same page” concerning the use of water resources for the cultivation of cannabis.

Nor would the air be spared

Cannabis seedlings

As they grow, cannabis plants produce many volatile organic compounds.

In addition to water pollution, American scientists draw attention to the fact that during their growth, cannabis plants emit many volatile organic compounds (VOCs), which have a crucial role in the formation of ozone and particles.

Among the most interesting VOCs would be the biogenic volatile organic compounds (VOCb), mainly emitted by vegetation, and which represent about 89% of the total atmospheric VOCs.

Regarding cannabis, the main VOCb emitted would be monoterpenes (C6H16), terpenoid compounds (eg eucalyptol; C10H18O), sesquiterpenes (C15H24), acetone and methanol.

Cannabis fertilization is problematic.

In 2019, a study attempted, for the first time, to make an inventory of cannabis-specific emissions and their environmental impact. Its findings indicate that for Denver County, where the research was conducted, hemp cultivation, depending on the scenarios, could cause hourly morning ozone concentrations to increase by approximately 0.34 ppb, and up to at 0.67 ppb at night.

The fertilization of cannabis was also singled out as a cause of deterioration in air quality, in particular due to the heavy use of chemical nitrogen fertilizers, containing ammonia. Ammonia which, following various reactions with acid compounds present in the atmosphere, could subsequently form residues including wet and dry deposits “continuously deteriorate the ecological environment”. Scientists then speak of risks of soil acidification and water eutrophication.

Indoor cultivation, a real energy gulf

A man in a cannabis cultivation greenhouse, full of light

The energy cost of growing cannabis indoors would be enormous.

In addition to the important problems already raised above, the cultivation of hemp leads to another, especially in the case of indoor cultivation, which this time concerns its energy demand. According to researchers reporting the results of a 2015 study, the cannabis industry is “one of the most energy-intensive industries in the United States”resulting in up to $6 billion in energy costs per year, or more than 1% of the electricity of the whole country.

Costs for which the lighting necessary for cultivation would be responsible for more than 89%, in particular because of the use of special cultivation lamps, the intensity of which is close to that used in operating rooms, i.e. an intensity of 500 times greater than that of traditional lighting.

The production of 1 kg of cannabis would lead to 4,600 kg of CO2 emissions into the atmosphere.

And since all this energy must be produced somewhere, the researchers point out that in the United States, energy production depends more than 75% on the use of coal and gas, whose environmental impacts are also, dramatic since they would have harmful effects on humans, animals, agricultural products, plants and forests, but also aquatic ecosystems or even buildings and other structures.

The scientists conclude by indicating that a study dated 2018 came to the conclusion that the production of 1 kg of cannabis would lead to 4,600 kg of CO2 emissions into the atmosphere, i.e. the production of a passenger vehicle driven for one year, or more than 18,000 km traveled by an average passenger vehicle.

Remy Beausoleil of Hemp’Solution

“Pesticides and other toxic products are the result of illegal cultivation.”

Rémy Beausoleil, founder of Hemp'Solution

Rémy Beausoleil, founder of Hemp’Solution

In California, cannabis growers are indeed forced to stock up on water in huge tanks to be able to irrigate all summer long. But you should know that the cultivation of medical cannabis is only authorized in organic. Again, pesticides and other toxic products are the result of illegal cultivation.

We farm in Northern California in Mendocino and we are at the heart of this great water debate. Every year, restrictions are put in place from the beginning of spring to limit access to water. We are allowed to pump and store water during the winter.

The problem of water comes mainly from the fact that there are many unauthorized crops that pump on the reserves. Sheriffs in each county are fighting hard against these crops.

As mentioned above, in fact, several studies demonstrate the ecological disaster that the pharmaceutical industry can be. I think that if we looked at the laboratories producing medicinal plants, we would find the same problem.

In France, we draw the vigilance of the ANSM concerning this subject. When writing the specifications, we are constantly reminded of the impact that this type of superstructure can have.

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