Skip to main content
NCBI home page
ACS AuthorChoice logoLink to ACS AuthorChoice
. 2024 Jun 11;4(7):690–699. doi: 10.1021/acsagscitech.4c00054

Environmental Impact of Outdoor Cannabis Production

Vincent Desaulniers Brousseau †, Benjamin P Goldstein †, Charlotte Sedlock ‡, Mark Lefsrud †,*
PMCID: PMC11253875  PMID: 39027629

Abstract

graphic file with name as4c00054_0005.jpg

Environmental impacts of cannabis production are of increasing concern because it is a newly legal and growing industry. Although a handful of studies have quantified the impacts of indoor production, very little is known about the impact of outdoor cannabis agriculture. Outdoor production typically uses little direct energy but can require significant fertilizer and other inputs due to dissipative losses via runoff and mineralization. Conversely, fertilizer high in nitrogen can be counterproductive, as it produces flowers with decreased cannabinoid content. This study has two aims: (1) To identify reduced-fertilizer regimes that provide optimal cannabis flower yields with reduced inputs and (2) to quantify how this shifts greenhouse gas emissions, resource depletion (fossil and metal), terrestrial acidification, and the eutrophication potential of outdoor cannabis production. Primary data from a fertilizer response trial are incorporated into a life-cycle assessment model. Results show that outdoor cannabis agriculture can be 50 times less carbon-emitting than indoor production. Dissemination of this knowledge is of utmost importance for producers, consumers, and government officials in nations that have either legalized or will legalize cannabis production.

Keywords: agriculture, cannabis, life-cycle assessment, greenhouse gas, cannabinoid, plant biology

Introduction

The rapid expansion of legal Cannabis sativa (cannabis) production raises questions regarding its resource use and environmental impacts.1 These impacts are critically understudied, as research to date has prioritized the medicinal aspects of cannabis.2 Limited data are available for cannabis cultivation, as 50% of the research on cannabis relates to the medical or food-related fields, while cannabis cultivation accounts for less than 1% of studies.2,3

To date, only two studies have investigated the carbon footprint of indoor cannabis production.4,5 They found that 1 kg of dried flower could produce between 2500 and 5000 kg CO2-equivalent (CO2-eq), a measure of global warming potential (GWP) emission. Of this, the vast majority of GHG emissions comes from the energy needed for grow room climate control via heating, ventilating, and air conditioning (HVAC) systems, supplemental lighting, and CO2. These emissions sources can be avoided by growing cannabis outdoors, where such energy-demanding technologies are not used,6 but there is a lack of empirical demonstrating this.

Outdoor cannabis production should emit much less CO2-eq compared to indoor cannabis production, but could come at the expense of forests, wildlife habitats and water quality, as observed with the Californian expansion of cannabis production.7 As in other agricultural crops grown outdoors, the most efficient way to reduce environmental externalities is by optimizing N-fertilizer use.10−14 Synthetic N-fertilizer use is associated with GHG emissions during its production and use phase.15 When N-fertilizer is applied in the field, nitrous oxide (N2O) is emitted.14 N2O is one of the most potent greenhouse gases, with a GWP 298 times the one of CO2 at an equivalent amount.16 N-fertilizer is a major driver of GWP in most crop production and can be responsible for up to 90% of the total carbon footprint.13,17

Furthermore, the waste nutrient solution is routinely discharged into the environment despite being loaded with fertilizer.18 This inefficient nutrient cycling threatens water quality through nutrient leaching and subsequent eutrophication, as well as decreases profit for growers.19,20 Scientifically informed guidelines are essential to prevent fertilizer-associated negative environmental externalities while increasing profit for farmers.21

Previous studies have shown that enhancing the N content in cannabis fertilizer results in larger plants, but the cannabinoid levels in both the flowers and leaves decrease.22−26 This reduction, known as the “dilution effect,” is partly attributed to a metabolic shift favoring the production of low-N metabolites under N deficiency.27 Leveraging this symptom of N deficiency could offer a sustainable approach to cannabis production, potentially reducing costs and environmental impacts associated with chemical N-fertilizer production and utilization while simultaneously boosting yields.13,21 Suboptimal N content in the fertilizer promotes the growth of stalked trichomes on the plant, plant structures responsible for the synthesis of Δ-9-tetrahydrocannabinol (THC), typically the most valuable active chemical in cannabis.28,29 Outdoor-grown cannabis plants have less oxidized and degraded cannabinoids than their indoor-grown counterpart, possibly caused by an increase in the antioxidant capacity of outdoor-grown plants.30 New data on increasing N-fertilizer efficiency could help optimize fertilizer use in outdoor cannabis production. Replacing some N-fertilizer inputs with K-fertilizer inputs is beneficial in other flower crops.31−33

Here, we assess potential tradeoffs between yield, THC, and environmental impacts through field trials of outdoor cannabis production combined with life-cycle assessment (LCA). LCA is a commonly used decision support tool in agriculture34−37 that can be used to guide farming practices and policies.38,39

The effect of different fertilizer recipes (varying N and K ratios) on the outputs of outdoor cannabis grown in Quebec, Canada, over three growing seasons was tested. Inputs of equipment and supplies at the farm were tracked. LCA was then used to quantify environmental impacts for the five indicators: GWP, marine and freshwater eutrophication potential (MFEP), terrestrial acidification (TA), fossil fuel depletion (FD), and metal resource depletion (MD). These impact categories were chosen based on pertinent issues related to the fertilizer supply chain and their capacity to differentiate between various forms of fertilizers.40−44

GWP was chosen to quantify the impact of N-fertilizer’s production and use, as production is associated with CO2 emission and use with N2O, a gas with 298 times greater global warming potential than CO2.12−16 TA by acid rain is assessed by measuring the impact of NH3 volatilization, SO2 emissions during electricity production, and NOx emissions associated with diesel combustion.43 MFEP assessed the impact of postapplication NO3 and P leaching as well as surface runoff.41 FD assessed the high energy-intensive production of N-containing fertilizers, while MD is representative of K-fertilizer production.42

In addition to providing the first full LCA of outdoor cannabis production, our study also brings novelty by quantifying impacts on both a yield basis and a THC basis. Previous studies have only focused on impacts per kilogram (kg) of dried flower.4,5 This ignores the potential impacts of production practices on the concentration of cannabinoids in the dried flower, thereby undermining the functional equivalence of the systems being compared, as it is ultimately these chemicals, and not the dried flower, that are of value to both medicinal and recreational growers.

The primary aim of our study is to address two key research questions:

  • (1)

    What reduced-fertilizer regimes can provide optimal cannabis flower yields with decreased inputs in outdoor cultivation?

  • (2)

    How does the implementation of reduced-fertilizer regimes in outdoor cannabis production impacts greenhouse gas emissions, resource depletion (fossil and metal), terrestrial acidification, and eutrophication potential?

Methods

This study combines fertilizer trials of open-field cannabis production with a detailed LCA. Below we outline the details of the field trials and statistical analysis used to analyze the effects of fertilizer regimes on yield and THC, and we then describe our LCA model.

Experimental Site

The study was conducted from 2020 to 2022 in an experimental farm near Thetford Mines, QC, Canada (46°10′52.824″N; 71°18′58.068″W), during the months of May–September. All three seasons were typical, averaging 290 mm precipitation and 13.5 °C. More details are given in Supporting Information, Table S1.

Plant Culture and Potting Condition

Cannabis plants insensitive to photoperiod were selected for their accelerated growth compared with traditional photoperiod-sensitive varieties. Traditional photoperiod-sensitive cannabis can exhibit variable maturation periods, and given the limited knowledge of suitable genotypes for our study location, there was a risk of crop failure due to premature frost and inadequate genotype selection. To mitigate these risks, feminized autoflowering seeds of the “Candy Cane” strain were employed. Among available options, “Candy Cane” stood out as the fastest-maturing genotype.

Seeds were germinated and then put in 12 L black pots filled with peat-based potting mix (ProMix HP, Premier Tech, Rivièredu-Loup, QC, Canada) with muriate of potash (KCl) and incorporated slow-release fertilizers (Osmocote classic 14-14-14, 3-4 months; Dublin, OH) composed of 5.8% nitrate N and 8.2% ammoniacal N. Irrigation was supplied via sprinkler every 2–3 days, and potted plants were randomly spaced at a density of 5.6 plants m–2.

Fertilizer Treatment

Each year, 36 seedlings were randomly divided into six treatments (n = 6) (Table 1). Three treatments used manufacturer recommended N levels of 3.2, 7.7, and 11.8 g of N per pot. These treatments had a fertilizer K/N ratio of 1. Three treatments used the same N levels but at a K/N ratio of 2:1 (3.2, 7.7, and 11.8 g K2O eq per pot). See Table 1 for fertilizer treatment and the associated alphanumeric code.

Table 1. Quantity of Fertilizer Used in the Six Treatmentsa.

  fertilizer treatment
code g N/pot g K/pot
L– 3.2 3.2
M– 7.7 7.7
H– 11.8 11.8
L+ 3.2 6.4
M+ 7.7 15.3
H+ 11.8 23.8
Open in a new tab
a

Associated alphanumerical code is shown where L, M, and H stand for low, medium, and high, respectively. The – and + signs stand for a K/N ratio of 1 and 2, respectively.

Harvest, Drying, Growth, and Yield Measurements

For three consecutive years (2020–2022), six plants per treatment were harvested at 10 weeks and assessed for flower yield. Fresh flowers from each treatment were combined and air-dried in a dark room for a week. Leaves were pooled once per treatment before drying. Randomly chosen samples from these treatment-pooled flowers and leaves were then sent for chemical analysis.

Chemical Analysis

As previously explained, the flowers and leaves within each treatment were pooled during the drying procedure. This effectively created a composite sample of the flower and leaves per treatment. Subsequently, from these composite samples, three technical replicates (n = 3) per treatment were analyzed for cannabinoid and N content for 2 successive years (2021–2022).

Total N was measured by combustion/thermal conductivity (Dumas method) For cannabinoids, treatment-pooled flowers were sent to a third-party lab (Phytochemia, Chicoutimi, QC, Canada). Cannabinoids were analyzed using standard methods45,46 (more details on the analysis are given in the Supporting Information, Supplemental Methods). THC content is on an anhydrous basis, and total THC is the sum of neutral and acid forms.

Statistical Analyses

The experiment was designed by using a complete randomized block design with six treatments, and each plant represented a single-year replicate. Collected data were analyzed using two-way analysis of variance (ANOVA) with fertilizer treatment and harvest year as the two categorical variables to determine the statistical significance of treatment, sampling year, and their interactive effects on whole plant Tukey–Kramer honestly significant difference (HSD) test was performed to compare means for all pairs. The relationship between leaf N content and flower total THC content was determined using a linear regression model.

Life-Cycle Assessment

The LCA consists of four stages: goal and scope definition, life-cycle inventory (LCI), life-cycle impact assessment (LCIA), and interpretation.

Life-Cycle Assessment Goal and Scope

The goal and scope of the study are to measure five environmental performance indicators associated with fertilizer use in outdoor cannabis agricultural: GWP, MFEP, TA, FD and MD. These indicators were chosen because of their direct links to synthetic fertilizer production and application All environmental impacts were normalized to a functional unit (FU) consisting of 1 kg of dried cannabis flower, as in other works.4,5 A novel FU of 100 g of THC was used for the first time. The reason for using 100 g of THC as an FU is important because it pertains to the potential variance in THC content between different fertilizer treatments. By using two different FU, the difference in quality between flowers is controlled, and the assumption of functional equivalence is maintained.

Functional equivalence refers to the principle that different products or processes can fulfill the same function or purpose.47 The use of different FUs acknowledges that this assumption may not hold true in all cases, particularly when variations in THC content can impact the environmental footprint of the product.

System boundaries covered cradle to farm gate, including raw materials’ extraction and processing, transport, cannabis production on site, and postharvest processing. Figure 1 outlines the study scope and product system in detail.

Figure 1.

Figure 1

Open in a new tab

System boundaries in our LCA of outdoor cannabis. Upstream processes include material inputs for building construction, fertilizer production and other chemicals, electricity, and production of machinery. Field operation includes plant growth, harvest, drying, and a modeled on-site steam sterilization for potting mix reuse. Transport, fertilizer use, and diesel combustion-associated emissions were also included.

Life-Cycle Inventory

LCI was compiled, detailing all relevant inputs and outputs of each production stage, which can be summed and converted to potential environmental impacts across the product’s life-cycle. Primary data collected during the field experiment were used as the foreground system. The mass of inputs, such as fertilizer, potting mix, plastic pots, and nylon trellis, were recorded using a scale.

To quantify the impact of bringing the inputs to the farm location, off-farm transportation, including travel by train, boat, and light vehicle distances, was simulated based on the most accurate available knowledge and cartographic data. On-farm transportation was simulated by modeling a 1 ha field that would require a tractor to pass 20 times over the growing season. Emission factors following fertilizer application were modeled as 1% of total N for N2O emission to air,16 21% of N2O emission for NOx emission to air,48 4% of total N for NH4 emission to air,48 12% of total P for PO4 to water 50, and 1% of total N for NO3 emission to water,44 and CO2 capture by plant growth was fixed as 50% of dried biomass. Drying was modeled after previous LCA studies on cannabis.5

All inputs were normalized to 1 kg of dried flower or 100 g of THC. Background data on material extraction and production processes were taken from the scientific literature, agricultural extension services, official industry communications, technical sheets, and the EcoInvent v3.8 database. Data sources, assumptions, and modeling details are presented in Supporting Information, Table S2 and Supplemental Methods.

Scenarios and Impact Assessments

To assess the potential of fertilizer treatment to modulate environmental performance, the LCA used primary data from two fertilizer treatments: H– and L+ (Table 1). These two treatments showed the biggest difference in flower yield and THC content. The environmental performance of both these treatments were compared using LCA. Furthermore, the impact of FU choice (100 g of THC or 1 kg dried flower) was also compared.

After the first modelization comparing fertilizer treatment L+ and H– was completed, another scenario modeled on-site steam sterilization of potting soil using a diesel-powered steamer. Because potting media drove most of the impacts, modeled on-site steaming was used to see if it would be more environmentally performant than acquiring new potting media every year. The system was modeled in OpenLCA software v2.0 (www.openlca.org) using the ReCiPe midpoint (hierarchist v.1.13) impact assessment method.49

Results

Effect of Fertilizer Treatment on the Flower and Cannabinoid Yield

Across sampling years, higher levels of the N-input were associated with an increase in the flower yield in all treatments (Figure 2A). Flower THC content and whole plant THC yield did not follow the same trend (Figure 2B,C). Most plant characteristics were significantly impacted by the interaction between treatment and sampling year, except flower yield (Supporting Information, Table S3).

Figure 2.

Figure 2

Open in a new tab

Effect of the fertilizer N level and the K/N ratio on cannabis plants. Cannabis dry flower yield (g per plant) (A), flower THC content (%) (B), THC yield (g THC per plant) (C), and linear regression between inflorescence THC content and leaf N content (D). Dashed lines are for treatment with a K/N ratio of 1, and continuous lines are for treatment with a K/N ratio of 2. Data are presented as LSmeans ± SE of plants harvested between 2020 and 2022 for A (n = 6) and as LSmeans ± SE of plants harvested between 2021 and 2022 for B–C–D (n = 3). Different letters represent the significant difference between treatment by Tukey HSD at α = 0.05. Additional parameters are shown in Figure S1.

Two fertilizer treatments stand out from the rest. The first one, L+ (low N and high K/N ratio), had the highest THC content. The second one, H– (high N and a K/N of 1), had the highest flower yield and total THC yield: 38 g of dry flower per plant and 3.9 g of THC per plant (Figure 2C). There was a statistically significant negative correlation between foliar N content and flower total THC content (p < 0.01) (Figure 2D). With the finding that low fertilizer treatment L+ could provide sizable THC quantities, it was sought out to compare how environmentally performant it was compared to H–.

Global Warming Potential of Outdoor Cannabis

GWP was calculated using measured input and output values from treatments L+ and H–. These two treatments were chosen as they had significantly different fertilizer quantities as well as flower and THC yield. The input and output from these treatments were used as the primary data for the LCA model.

When accounting for raw material extraction, transformation, transport, and plant growth, the average GWP for cannabis grown using the H-fertilizer treatment is 61.8 kg CO2-eq per kg of dry flower. For cannabis grown with the L+ treatment, the GWP was calculated to be 110.7 kg CO2-eq per kg of dry flower, almost double the H– treatment (Figure 3).

Figure 3.

Figure 3

Open in a new tab

Drivers of GWP in outdoor cannabis production. GWP for FUs of 1 kg of dried flower and 100 g of THC are shown for the high fertilizer-input treatment (H−) and low fertilizer-input treatment (L+), respectively. Total process GHG emission is shown and subanalysis of the transport process as well as the subanalysis of the fertilizer process.

To assess if the increase in THC content in the L+ treatment would increase the environmental performance of outdoor cannabis production, the LCA was repeated using THC as the FU. In treatment H+, the change in FU only slightly affected the GWP with a 2% decrease in GWP: 60.7 kg CO2-eq per 100 g of THC. Conversely, when using 100 g of THC as the FU using values of treatment L+, GWP was calculated to be 91.7 kg CO2-eq.

Potting Media Drives the Majority of the Global Warming Potential

Potting media contributed between 65 and 75% of the GWP impacts in both treatments. The potting media production, being predominantly made of peat moss, is a highly CO2-emitting process. Furthermore, because treatment L+ requires roughly 50 plants to produce 1 kg of dry flower compared to 25 for treatment H–, this effectively doubles the volume of growing media needed in the L+ fertilizer treatment, making it much more GHG intensive than H-.

Analysis of the transport process shows that it contributes <10% of the total GWP, and that freight vehicles had the most impact on CO2 footprint or around 97% of total transport-related GHG emission. Again, the H– treatment, requiring fewer plants and associated potting media to produce 1 kg of dry flower, had significantly less GWP than the L+ treatment. Fertilizer processes (production and use) were the only ones with a smaller GWP in treatment L+.

High Environmental Impact of Potting Media

This study aligns with others showing how the environmental burden of outdoor production in pots or raised beds is driven by potting media.50,51 Enabling on-site potting media reuse instead of acquiring fresh potting media every growth cycle can reduce these impacts.52,53

To assess the environmental performance of reusing potting media, a scenario was run modeling on-site steam sterilization of media using H-fertilizer treatment. This model assumed a decrease in necessary potting media and associated transport but an increase in agricultural machinery and diesel consumption. We incorporated an on-site agricultural steamer using 26 L of diesel per m3 of used potting mix into the LCA model.54

Using the fertilizer treatment H– to produce 100 g of THC has a GWP of 60.7 kg CO2-eq per 100 g of THC. The modeled on-site potting media reuse via steaming decreased the GWP of 100 g of THC to a value of 52.7 kg CO2-eq.

The most GHG-emitting process when reusing potting media was steam sterilization via diesel combustion in agricultural machinery. Transport-associated GWP decreased by 85% when using on-site reuse of potting media because of the absence of annual potting media delivery (Supporting Information, Table S5). Transport had a GWP of 6 kg CO2-eq per FU when using fresh potting mix every year versus 0.8 kg CO2-eq per FU when reusing it. Using new potting media has a GHG emission of 41.5 kg CO2-eq per FU, 10-fold the value of 4.2 kg CO2-eq per FU when reusing it on site. The main process to decrease when using fresh potting media every year was ‘tractor and steamer operation’, specifically diesel consumption. When reusing potting media via steam sterilization, tractor operation was estimated to generate 36 kg CO2-eq per FU. When using fresh potting media, the GWP value of the tractor process is <0.1 kg CO2-eq per FU.

Impacts of Outdoor Cannabis in Other Dimensions

Further analysis only used 100 g of THC as FU. Comparing GWP, MFEP, TA, FD, and MD showed how treatment H– without potting media reuse seems to have overall better environmental performances than L+ or H– with potting media reuse (Figure 4). H– and L+ without potting media reuse seem to have the lowest marine eutrophication potential and MD potential.

Figure 4.

Figure 4

Open in a new tab

Impact category results for the different fertilizer treatments H– or L+ for all life-cycle stages to produce 100 g of THC. Results from modeling of the H-fertilizer treatment with on-site potting media reuse via steam sterilization are shown.

Fossil Fuel Depletion

When fresh potting media was used every year, the processes with the most impact were potting media production, especially perlite production with 40–45% contribution in treatment H– and L+. The need to transport potting media will drive transport-associated externalities, contributing to around 25% of this indicator (Supporting Information, Table S6).

In the on-site reuse of potting media scenario, most of this indicator impact is driven by diesel combustion (78%), and the second contributing process is horticultural input (low-density polypropylene (LDPE) plastic, nylon, reused potting media), accounting for 7%.

Terrestrial Acidification

When fresh potting media is used every year, roughly 50–60% of it is caused by potting media production. The second most contributing process for the H– treatment is fertilizer production, accounting for 24% of the impact. The contribution of fertilizer in the L+ treatment decreased to 9%. Like fossil fuel depletion, diesel combustion is what drives most (74%) of this indicator when on-site reuse of potting media is done (Supporting Information, Table S7).

Eutrophication

Fertilizer accounts for 66–67% of the impact in a freshwater environment in treatment H– regardless of potting media reuse. This decreases to 38% in treatment L+. Again, the increase in necessary potting media and associated transport drives the rest of the impact, with a higher impact in L+ treatment, as it requires more of these processes. Marine eutrophication potential is driven by diesel combustion, which is responsible for 70% of the impact when reusing potting media (Supporting Information, Table S8).

Metal Depletion

As in other impact categories, in the potting reuse scenario, tractor and steamer use was the most contributing process (69%). When fresh potting media are used, potting media production becomes the most contributing process, with 25 and 38% of the total impact in treatments H– and L+. H– treatments have a lower impact as they require fewer potting media. Interestingly, the drying process (shed and electricity) is responsible for 50% of the impact in the H– treatment and 38% in the L+ treatment. In the potting media reuse scenario, this is closer to 22% (Supporting Information, Table S9).

Discussion

This study is the first to use results from a fertilizer response trial with a cannabis plant as foreground data for an LCA. The observed increase in THC content using the N-deficiency response of cannabis with an ample supply of K was not enough to make it competitive with a high N-input fertilizer treatment. Even if the environmental performance of K-fertilizer production and use is higher than that of N-fertilizer production and use, it did not translate into a substantial increase in environmental performance for outdoor cannabis production.

Previous studies on cannabis fertilizer response used nitrogen use efficiency (NUE) (dry flower yield over total N input) to assess the environmental performance of the fertilizer treatment.25,26 In accordance with the literature, it was observed that higher N-input fertilizer treatment seems to decrease NUE. While this captures how efficiently the plant transforms the N fertilizer into biomass, it overlooks the effect on producing THC.

The “dilution effect” shows how total THC concentration decreases as the N input increases.23−26,55,56 However, one treatment (low N and high K) significantly affected the total THC content in this study. This could be the first report of a fertilizer treatment affecting cannabinoid content at this magnitude (∼30% increase). This was caused by N deficiency, as evidenced by leaf N content being between 1.5 and 2.5% as opposed to 2.2 and 4.3% in plants with sufficient N.57,58 This has been observed with tobacco plants (Nicotiana tabacum) and hops (Humulus lupulus), where phenolic and alkaloid secondary metabolites content increase under N deficiency.59,60 This LCA is the first to explore the potential benefits of this compound for cannabis.

Even if L+ fertilizer treatment increases THC content, it is associated with a decrease in flower or THC yield on a per-plant basis. This decrease in per-plant yield drove a need for other inputs, notably potting media and subsequent GWP and other indicator MFEP.

It should be noted that the decision to use potting media in the fertilizer response was to control the nutrient content of soil across the years. Cannabis producers with appropriate machinery for soil work may not need potting media for outdoor production. This would undoubtedly greatly decrease the carbon footprint of the L+ treatment, where potting media drive most of its impact. Future studies could focus on estimating yield differences in potting media versus soil.

One limitation of this LCA study is translating findings to the real-world industry. Hypothetically, if a low N-fertilizer input was as efficient at increasing THC in soil agriculture, there would still be no incentive for growers to use this treatment. It would achieve a lower total yield per area at a similar planting density, resulting in increased land use, which has already known consequences in cannabis agriculture.8−10 Future studies could investigate the difference in total area yield of high planting density of smaller, more THC-concentrated cannabis plants versus bigger and less concentrated plants.

Life-Cycle Assessment Interpretation

This is the first study looking at environmental externalities other than GWP. Carbon footprint studies for cannabis have historically used 1 kg of dried flowers as their FU. However, when using primary data from two fertilizer treatments studied here, L+ and H–, it was shown how the FU choice would only slightly affect LCA conclusions. The choice of FU did modulate the environmental impact when looking at the L+ treatment but did not have a significant impact on the H– treatment.

However, it is important to keep monitoring for cannabinoid content increase. For example, a producer focused on extracting, where doses are calculated as mg of THC according to the Canadian law,61 would increase its marketable output proportionally to its THC increase. Combining the N-deficiency response with a higher planting density without relying on potting media could be beneficial for an extract producer who would be interested in ecolabeling or carbon tax credit. Total THC yield will dictate how many units can be sold, the product’s environmental impact, and the grower’s final profit. For reference, cannabis flowers with no report of THC content could become a flawed FU, as it seems that dried flowers are decreasing in popularity among Canadian users, with 60% of people reporting using it in the past 12 months in 2023, versus 80% in 2018.62 Conversely, the proportion of people reporting to have used edible has been steadily increasing in the past years, from 40% in 2018 to 55% in 2023.62 Extracts now represent roughly 30% of the sales in Canada,63 which means THC quantity as a FU could become more relevant.

This study highlights a significant finding: while outdoor cannabis production appears to emit 50 times less than its indoor counterpart, it still carries a notable emission burden, ranging from 61.8 to 110.7 kg CO2-eq per kg of dried flowers. Surprisingly, when compared to outdoor-grown food and drug products sharing similar production methods and consumer applications, the GWP of outdoor cannabis is notably higher. For instance, the emissions from outdoor cannabis exceed those from field-grown tobacco by a factor of at least 95 (0.64 kg CO2-eq per kg of green tobacco).64 Moreover, the emissions per kilogram of outdoor-grown dried flowers far surpass those associated with fruits and vegetables in previous studies.65,66 To illustrate, the emissions from outdoor-grown flowers exceed those of outdoor-grown tomatoes by a staggering factor of 1200 (0.05 kg CO2-eq per kg of tomatoes).67 Despite the inherent limitations in these comparisons stemming from variations in production regions, practices, and FU, substantial emissions from outdoor cannabis cannot be ignored.

Certain parameters can explain this great disparity between the GWP of outdoor cannabis calculated here versus the one calculated for agricultural products. First, in terms of economy of scale, our study modeled transport via small vehicles, resulting in higher emissions (10 kg CO2), whereas freight transport would have significantly reduced this footprint below 1 kg CO2. Second, water mass plays a crucial role; a single tomato plant typically yields much more in kilograms than a cannabis plant, especially considering that the dry mass is the FU for cannabis production. Lastly, genotype variations, particularly using different varieties suited for warmer climates, could substantially increase the yield and potentially reduce emissions.

In terms of practical steps, growers aiming to enhance their environmental performance while using potted media are encouraged to explore alternatives, such as locally sourced materials, thus reducing reliance on on-site steaming. Bioresources, including treated agricultural waste, present promising sustainable alternatives.68 Additionally, the conclusion regarding the reuse of on-site potting media suggests that while it may marginally decrease GWP, other environmental indicators are adversely affected by this practice.

Future Work

For future studies, looking at the industry total GWP by considering the entire Canadian volume of production would help in sizing the environmental burden on the industry. If this turned out to be a very large number, then the industry might look at outdoor growing to mitigate GHG emissions. It is important to point out that the GWP of outdoor cannabis could be 20–50 times lower than indoor-grown cannabis.4,5

Furthermore, a comparison with other industries is needed. For example, a comparison with other intoxicating products would be needed to compare the scale of the industry’s environmental impacts with other sectors, such as food or alcohol. For example, if 1 kg of outdoor cannabis produces 60 kg CO2-eq but provides 2000 units of 0.5 g smokable joints, one joint or “’unit’” of cannabis has a GWP of 0.03 kg CO2-eq. If trying to compare recreational cannabis use with alcohol, where a 0.75 L unit of wine has a GWP of 2 kg CO2-eq,68 there would be a need for careful FU selection to compare both. Perhaps “altered conscience” could permit a direct comparison of both industries. This study seems to show that a 0.5 g unit of outdoor cannabis could be 40 times less GHG-emitting than a 0.75 L unit of Portuguese white vinho verde, for instance.68

The same comparison can be made in the medical sector. Comparing medical cannabis production with conventional pharmaceutical production would require appropriate FU selection. Perhaps one dose of the selected pharmaceutical product having equivalent analgesic or antinausea would be a useful FU to use.

In conclusion, this study sheds light on the environmental impacts of outdoor cannabis agriculture, an increasingly significant aspect of the newly legalized and expanding cannabis industry. While previous research has focused largely on indoor production, our study addresses the critical gap in understanding the environmental implications of outdoor cultivation methods. By examining reduced-fertilizer regimes, we aimed to optimize cannabis flower yields while minimizing inputs, considering the intricate balance between nutrient requirements and cannabinoid content. Incorporating primary data from a fertilizer response trial into an LCA model, our findings highlight the potential for significant reductions in GWP, FD, TA, MFEP, and MD compared to indoor production methods. Such insights are paramount for stakeholders, including producers, consumers, and policymakers in nations with existing or forthcoming legalization frameworks, facilitating informed decision-making to mitigate environmental impacts while supporting sustainable cannabis production practices.

Glossary

Abbreviations

CO2-equiv

carbon dioxide equivalent

FD

fossil fuel depletion

FU

functional unit

GHG

greenhouse gas

GWP

global warming potential

HVAC

heating, ventilating and air conditioning

LCA

life-cycle assessment

LCI

life-cycle inventory

LCIA

life-cycle impact assessment

MD

metal resource depletion

MFEP

marine and freshwater eutrophication potential

NUE

nitrogen use efficiency

TA

terrestrial acidification

THC

Δ-9-tetrahydrocannabinol

Supporting Information Available

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsagscitech.4c00054.

  • Additional experimental details, materials, and methods, including source to OpenLCA code “EnvImpactOutdoorCannabis.zip” is a file containing the OpenLCA code in JSON format (Table S1 calculations). Excel workbook with calculations and references for Table S1 (Supplemental Information.doc). Written file containing Supplemental Methods: additional information for the Method section that is not crucial for understanding the experiment (Figure S1) effect of the fertilizer N-level and the K/N ratio on cannabis plants; and (Table S1) summary of growing season parameters, (Table S2) LCI and data source for the model with and without on-site potting media reuse via steaming. (Table S4) Nutrient content measured in potting media used. (Table S3) Significance of the effects of treatment, sampling year, and their interactions. (Table S5) Main processes contribution to the global warming potential of the outdoor cannabis plant with or without on-site potting media reuse at varying fertilizer treatments. (Table S6) Main process contribution to fossil fuel depletion of outdoor cannabis plant with or without on-site potting media reuse. (Table S7) Main processes’ contribution to terrestrial acidification of outdoor cannabis plant with or without on-site potting media reuse. (Table S8) Main processes’ contribution to the marine and freshwater eutrophication potential of the outdoor cannabis plant with or without on-site potting media reuse. (Table S9) Main processes’ contribution to metal depletion potential of outdoor cannabis plant with or without on-site potting media reuse (PDF)

Author Present Address

§ School for Environment and Sustainability, University of Michigan, 440 Church Street, Ann Arbor, MI 48109, United States

Author Contributions

V.D.B. contributed to conceptualization, methodology, software, formal analysis, validation, data curation, and writing—original draft preparation; V.D.B., C.S., and B.P.G. contributed to investigation and writing—review and editing; M.L. contributed to project administration and funding acquisition. All authors have read and agreed to the version of the manuscript.

The authors acknowledge the support of the Natural Sciences and Engineering Research Council of Canada (NSERC; CRDPF 543704-19 and CREATE 543319-2020) and EXKA Inc. for their continuous support and funding of this project.

The authors declare no competing financial interest.

Special Issue

Published as part of ACS Agricultural Science & Technologyvirtual special issue “AGRO Division 50th Anniversary”.

Supplementary Material

as4c00054_si_001.pdf (172.7KB, pdf)

References

  1. Wartenberg A. C.; Holden P. A.; Bodwitch H.; Parker-Shames P.; Novotny T.; Harmon T. C.; Hart S. C.; Beutel M.; Gilmore M.; Hoh E.; Butsic V. Cannabis and the Environment: What Science Tells Us and What We Still Need to Know. Environ. Sci. Technol. Lett. 2021, 8 (2), 98–107. 10.1021/acs.estlett.0c00844. [DOI] [Google Scholar]
  2. Vujanovic V.; Korber D. R.; Vujanovic S.; Vujanovic J.; Jabaji S. Scientific Prospects for Cannabis-Microbiome Research to Ensure Quality and Safety of Products. Microorganisms 2020, 8 (2), 290 10.3390/microorganisms8020290. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Hussain T.; Jeena G.; Pitakbut T.; Vasilev N.; Kayser O. Cannabis Sativa Research Trends, Challenges, and New-Age Perspectives. iScience 2021, 24, 103391 10.1016/j.isci.2021.103391. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Mills E. The Carbon Footprint of Indoor Cannabis Production. Energy Policy 2012, 46, 58–67. 10.1016/j.enpol.2012.03.023. [DOI] [Google Scholar]
  5. Summers H. M.; Sproul E.; Quinn J. C. The Greenhouse Gas Emissions of Indoor Cannabis Production in the United States. Nat. Sustainability 2021, 4 (7), 644–650. 10.1038/s41893-021-00691-w. [DOI] [Google Scholar]
  6. Wilson H.; Bodwitch H.; Carah J.; Daane K.; Getz C.; Grantham T. E.; Butsic V. First Known Survey of Cannabis Production Practices in California. Calif. Agric. 2019, 73 (3), 119–127. 10.3733/ca.2019a0015. [DOI] [Google Scholar]
  7. Butsic V.; Carah J. K.; Baumann M.; Stephens C.; Brenner J. C. The Emergence of Cannabis Agriculture Frontiers as Environmental Threats. Environ. Res. Lett. 2018, 13 (12), 124017 10.1088/1748-9326/aaeade. [DOI] [Google Scholar]
  8. Butsic V.; Brenner J. C. Cannabis (Cannabis Sativa or C. Indica) Agriculture and the Environment: A Systematic, Spatially-Explicit Survey and Potential Impacts. Environ. Res. Lett 2016, 11 (4), 044023 10.1088/1748-9326/11/4/044023. [DOI] [Google Scholar]
  9. Wang I. J.; Brenner J. C.; Butsic V. Cannabis, an Emerging Agricultural Crop, Leads to Deforestation and Fragmentation. Front. Ecol. Environ. 2017, 15 (9), 495–501. 10.1002/fee.1634. [DOI] [Google Scholar]
  10. Xu G.; Fan X.; Miller A. J. Plant Nitrogen Assimilation and Use Efficiency. Annu. Rev. Plant Biol. 2012, 63, 153–182. 10.1146/annurev-arplant-042811-105532. [DOI] [PubMed] [Google Scholar]
  11. Chen X.; Ma C.; Zhou H.; Liu Y.; Huang X.; Wang M.; Cai Y.; Su D.; Muneer M. A.; Guo M.; Chen X.; Zhou Y.; Hou Y.; Cong W.; Guo J.; Ma W.; Zhang W.; Cui Z.; Wu L.; Zhou S.; Zhang F. Identifying the Main Crops and Key Factors Determining the Carbon Footprint of Crop Production in China, 2001–2018. Resour., Conserv. Recycl. 2021, 172 (May), 105661 10.1016/j.resconrec.2021.105661. [DOI] [Google Scholar]
  12. Gao Y.; Cabrera Serrenho A. Greenhouse Gas Emissions from Nitrogen Fertilizers Could Be Reduced by up to One-Fifth of Current Levels by 2050 with Combined Interventions. Nat. Food 2023, 4 (2), 170–178. 10.1038/s43016-023-00698-w. [DOI] [PubMed] [Google Scholar]
  13. Snyder C. S.; Bruulsema T. W.; Jensen T. L.; Fixen P. E.. Review of Greenhouse Gas Emissions from Crop Production Systems and Fertilizer Management Effects. In Agriculture, Ecosystems and Environment; Elsevier, 2009; Vol. 1, pp 247–266. [Google Scholar]
  14. Chen H.; Li X.; Hu F.; Shi W. Soil Nitrous Oxide Emissions Following Crop Residue Addition: A Meta-Analysis. Global Change Biol. 2013, 19 (10), 2956–2964. 10.1111/gcb.12274. [DOI] [PubMed] [Google Scholar]
  15. IPNI . Nitrogen Fertilizer Production and Technology. http://nitrogen.ipni.net/article/NNN-5037 (accessed Sept 15, 2018).
  16. IPCC . Climate Change 2014: Synthesis Report; Pachauri R. K.; Meyer L. A.. 2014 10.1016/S0022-0248(00)00575-3. [DOI]
  17. Rosenfield J.; Lewandrowsky J.; Hendrickson T.; Jaglo K.; Moffroid K.; Pape D.. A Life-Cycle Analysis of the Greenhouse Gas Emissions from Corn-Based Ethanol; 2018.
  18. Mohammed N.The Advantages of a Closed Hydroponic System in Commercial Greenhouses Greenhouse Research & Production Complex; 2017. [Google Scholar]
  19. Huang J.; Xu C.-c.; Ridoutt B. G.; Wang X.-c.; Ren P.-a. Nitrogen and Phosphorus Losses and Eutrophication Potential Associated with Fertilizer Application to Cropland in China. J. Cleaner Prod. 2017, 159, 171–179. 10.1016/j.jclepro.2017.05.008. [DOI] [Google Scholar]
  20. Kumar R. R.; Cho J. Y. Reuse of Hydroponic Waste Solution. Environ. Sci. Pollut. Res. 2014, 20, 9569–9577. 10.1007/s11356-014-3024-3. [DOI] [PubMed] [Google Scholar]
  21. Menegat S.; Ledo A.; Tirado R. Greenhouse Gas Emissions from Global Production and Use of Nitrogen Synthetic Fertilisers in Agriculture. Sci. Rep. 2022, 12 (1), 14490 10.1038/s41598-022-18773-w. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Bócsa I.; Máthé P.; Hangyel L. Effect of nitrogen on tetrahydrocannabinol (THC) content in hemp (Cannabis sativa L.) leaves at different positions. J. Int. Hemp Assoc. 1997, 4 (2), 78–79. [Google Scholar]
  23. Caplan D.; Dixon M.; Zheng Y. Optimal Rate of Organic Fertilizer during the Vegetative-Stage for Cannabis Grown in Two Coir-Based Substrates. HortScience 2017, 52 (9), 1307–1312. 10.21273/HORTSCI11903-17. [DOI] [Google Scholar]
  24. Caplan D.; Dixon M.; Zheng Y. Optimal Rate of Organic Fertilizer during the Flowering Stage for Cannabis Grown in Two Coir-Based Substrates. HortScience 2017, 52 (12), 1796–1803. 10.21273/HORTSCI12401-17. [DOI] [Google Scholar]
  25. Saloner A.; Bernstein N. Nitrogen Supply Affects Cannabinoid and Terpenoid Profile in Medical Cannabis (Cannabis Sativa L.). Ind. Crops Prod. 2021, 167 (December 2020), 113516 10.1016/j.indcrop.2021.113516. [DOI] [Google Scholar]
  26. Saloner A.; Bernstein N. Response of Medical Cannabis (Cannabis Sativa l.) to Nitrogen Supply under Long Photoperiod. Front. Plant Sci. 2020, 11, 1517. 10.3389/fpls.2020.572293. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Song C.; Saloner A.; Fait A.; Bernstein N. Nitrogen Deficiency Stimulates Cannabinoid Biosynthesis in Medical Cannabis Plants by Inducing a Metabolic Shift towards Production of Low-N Metabolites. Ind. Crops Prod. 2023, 202, 116969 10.1016/j.indcrop.2023.116969. [DOI] [Google Scholar]
  28. Tanney C. A. S.; Lyu D.; Schwinghamer T.; Geitmann A.; Ruan E. D.; Smith D. L. Sub-Optimal Nutrient Regime Coupled with Bacillus and Pseudomonas Sp. Inoculation Influences Trichome Density and Cannabinoid Profiles in Drug-Type Cannabis Sativa. Front. Plant Sci. 2023, 14 (May), 1–10. 10.3389/fpls.2023.1131346. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Tanney C. A. S.; Backer R.; Geitmann A.; Smith D. L. Cannabis Glandular Trichomes: A Cellular Metabolite Factory. Front. Plant Sci. 2021, 12, 721986 10.3389/fpls.2021.721986. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Zandkarimi F.; Decatur J.; Casali J.; Gordon T.; Skibola C.; Nuckolls C. Comparison of the Cannabinoid and Terpene Profiles in Commercial Cannabis from Natural and Artificial Cultivation. Molecules 2023, 28 (2), 1–15. 10.3390/molecules28020833. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Heidemann J. C.; Barbosa J. G. Production and Quality of Three Varieties of Chrysanthemum Grown in Pots with Different NPK Rates. Ornamental Hortic. 2017, 23 (4), 426–431. 10.14295/oh.v23i4.1020. [DOI] [Google Scholar]
  32. Barbosa J. G.; Kampf A. N.; Martinez H. E. P.; Koller O. C.; Bohnen H. Chrysanthemum Cultivation in Expanded Clay. I. Effect of the Nitrogen-phosphorus-potassium Ratio in the Nutrient Solution. J. Plant Nutr. 2000, 23 (9), 1327–1336. 10.1080/01904160009382103. [DOI] [Google Scholar]
  33. Barbosa J. G.; Barbosa M. S.; Almeida D. B.; Sá P. G.; Finger F. L.; Martinez H. E. P.; Grossi J. A. S. Production and Postharvest Quality of Chrysanthemum Flowers Grown in Hydroponic System Under Different N:K Ratios. Acta Hortic. 2015, 1060, 281–287. 10.17660/ActaHortic.2015.1060.42. [DOI] [Google Scholar]
  34. Antón A.; Torrellas M.; Montero J. I.; Ruijs M.; Vermeulen P.; Stanghellini C. Environmental Impact Assessment of Dutch Tomato Crop Production in a Venlo Glasshouse. Acta Hortic. 2012, 927, 781–792. 10.17660/actahortic.2012.927.97. [DOI] [Google Scholar]
  35. Maham S. G.; Rahimi A.; Subramanian S.; Smith D. L. The Environmental Impacts of Organic Greenhouse Tomato Production Based on the Nitrogen-Fixing Plant (Azolla). J. Cleaner Prod. 2020, 245, 118679 10.1016/j.jclepro.2019.118679. [DOI] [Google Scholar]
  36. Tabatabaie S. M. H.; Murthy G. S. Cradle to Farm Gate Life Cycle Assessment of Strawberry Production in the United States. J. Cleaner Prod. 2016, 127, 548–554. 10.1016/j.jclepro.2016.03.175. [DOI] [Google Scholar]
  37. Zheng Z.; Fiddes K.; Yang L. A Narrative Review on Environmental Impacts of Cannabis Cultivation. J. Cannabis Res. 2021, 3 (1), 35 10.1186/s42238-021-00090-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. International Organization for Standardization. ISO 14044: Environmental Management—Life Cycle Assessment—Requirements and Guidelines 2006, https://www.iso.org/obp/ui/#iso:std:iso:14044:ed-1:v1:en (accessed 2023–01–29).
  39. International Organization for Standardization. ISO 14040-Environmental Management—Life Cycle Assessment—Principles and Framework, 2006, Geneva, Switzerland.
  40. Brentrup F.; Küsters J.; Lammel J.; Barraclough P.; Kuhlmann H. Environmental Impact Assessment of Agricultural Production Systems Using the Life Cycle Assessment (LCA) Methodology II. The Application to N Fertilizer Use in Winter Wheat Production Systems. Eur. J. Agron. 2004, 20 (3), 265–279. 10.1016/S1161-0301(03)00039-X. [DOI] [Google Scholar]
  41. Brentrup F.; Küsters J.; Kuhlmann H.; Lammel J. Environmental Impact Assessment of Agricultural Production Systems Using the Life Cycle Assessment Methodology: I. Theoretical Concept of a LCA Method Tailored to Crop Production. Eur. J. Agron. 2004, 20 (3), 247–264. 10.1016/S1161-0301(03)00024-8. [DOI] [Google Scholar]
  42. Skowrońska M.; Filipek T. Life Cycle Assessment of Fertilizers: A Review. Int. Agrophys. 2014, 28 (1), 101–110. 10.2478/intag-2013-0032. [DOI] [Google Scholar]
  43. Roy P. O.; Deschênes L.; Margni M. Life Cycle Impact Assessment of Terrestrial Acidification: Modeling Spatially Explicit Soil Sensitivity at the Global Scale. Environ. Sci. Technol. 2012, 46 (15), 8270–8278. 10.1021/es3013563. [DOI] [PubMed] [Google Scholar]
  44. Hasler K.; Bröring S.; Omta S. W. F.; Olfs H. W. Life Cycle Assessment (LCA) of Different Fertilizer Product Types. Eur. J. Agron. 2015, 69, 41–51. 10.1016/j.eja.2015.06.001. [DOI] [Google Scholar]
  45. De Backer B.; Debrus B.; Lebrun P.; Theunis L.; Dubois N.; Decock L.; Verstraete A.; Hubert P.; Charlier C. Innovative Development and Validation of an HPLC/DAD Method for the Qualitative and Quantitative Determination of Major Cannabinoids in Cannabis Plant Material. J. Chromatogr. B: Anal. Technol. Biomed. Life Sci. 2009, 877 (32), 4115–4124. 10.1016/j.jchromb.2009.11.004. [DOI] [PubMed] [Google Scholar]
  46. Orlowicz S.; Krepich S.; Aqeel Z.; Layne J.. 18 Cannabinoids for Potency Testing by LC-UV, 2020. https://www.phenomenex.com/documents/2020/11/04/06/17/18-cannabinoids-for-potency-testing-by-lc-uv.
  47. Tyszler M.; Kramer G.; Blonk H. Comparing apples with oranges: On the functional equivalence of food products for comparative LCAs. Int. J. Life Cycle Assess. 2014, 19 (8), 1482–1487. 10.1007/s11367-014-0762-x. [DOI] [Google Scholar]
  48. Nemecek T.; Kägi T.. Life Cycle Inventories of Agricultural Production Systems; Ecoinvent Report, 2007; 2797. https://db.ecoinvent.org/reports/15_Agriculture.pdf.
  49. Huijbregts M. A. J.; Steinmann Z. J. N.; Elshout P. M. F.; Stam G.; Verones F.; Vieira M.; Zijp M.; Hollander A.; van Zelm R. ReCiPe2016: A Harmonised Life Cycle Impact Assessment Method at Midpoint and Endpoint Level. Int. J. Life Cycle Assess. 2017, 22 (2), 138–147. 10.1007/s11367-016-1246-y. [DOI] [Google Scholar]
  50. Lazzerini G.; Lucchetti S.; Nicese F. P. Green House Gases(GHG) Emissions from the Ornamental Plant Nursery Industry: A Life Cycle Assessment(LCA) Approach in a Nursery District in Central Italy. J. Cleaner Prod. 2016, 112, 4022–4030. 10.1016/j.jclepro.2015.08.065. [DOI] [Google Scholar]
  51. Russo G.; De Lucia B.; Vecchietti L.; Rea E.; Leone A. Environmental and Agronomical Analysis of Different Compost-Based Peat-Free Substrates in Potted Rosemary. Acta Hortic. 2011, 891, 265–272. 10.17660/ActaHortic.2011.891.32. [DOI] [Google Scholar]
  52. Vandecasteele B.; Similon L.; Moelants J.; Hofkens M.. Cascading Use of Renewable Growing Media versus Peat or Mineral Wool: Added Value of Biochar for End-of-Life, Recycling of Nutrients and C Storage Potential; Springer, 2022; pp 1–21. [Google Scholar]
  53. Vandecasteele B.; Blindeman L.; Amery F.; Pieters C.; Ommeslag S.; Van Loo K.; De Tender C.; Debode J. Grow - Store - Steam - Re-Peat: Reuse of Spent Growing Media for Circular Cultivation of Chrysanthemum. J. Cleaner Prod. 2020, 276, 124128 10.1016/j.jclepro.2020.124128. [DOI] [Google Scholar]
  54. Arancibiata R. A.Soil Steaming to Reduce the Incidence of Soil-borne Diseases, Weeds and Insect Pests. Missouri Produce Growers Bulletin, 2020, https://ipm.missouri.edu/MPG/2020/11/steaming-RA/ (accessed May 8, 2023).
  55. Massuela D. C.; Munz S.; Hartung J.; Nkebiwe P. M.; Graeff-Hönninger S. Cannabis Hunger Games: Nutrient Stress Induction in Flowering Stage – Impact of Organic and Mineral Fertilizer Levels on Biomass, Cannabidiol (CBD) Yield and Nutrient Use Efficiency. Front. Plant Sci. 2023, 14, 151. 10.3389/fpls.2023.1233232. [DOI] [PMC free article] [PubMed] [Google Scholar]
  56. Dilena E.; Close D. C.; Hunt I.; Garland S. M. Investigating How Nitrogen Nutrition and Pruning Impacts on CBD and THC Concentration and Plant Biomass of Cannabis Sativa. Sci. Rep. 2023, 13 (1), 19533 10.1038/s41598-023-46369-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  57. Cockson P.; Landis H.; Smith T.; Hicks K.; Whipker B. E. Characterization of Nutrient Disorders of Cannabis Sativa. Appl. Sci. 2019, 9 (20), 4432 10.3390/app9204432. [DOI] [Google Scholar]
  58. Llewellyn D.; Golem S.; Jones A. M. P.; Zheng Y. Foliar Symptomology, Nutrient Content, Yield, and Secondary Metabolite Variability of Cannabis Grown Hydroponically with Different Single-Element Nutrient Deficiencies. Plants 2023, 12 (3), 422 10.3390/plants12030422. [DOI] [PMC free article] [PubMed] [Google Scholar]
  59. Fritz C.; Palacios-Rojas N.; Feil R.; Stitt M. Regulation of Secondary Metabolism by the Carbon-Nitrogen Status in Tobacco: Nitrate Inhibits Large Sectors of Phenylpropanoid Metabolism. Plant J. 2006, 46 (4), 533–548. 10.1111/j.1365-313X.2006.02715.x. [DOI] [PubMed] [Google Scholar]
  60. Tadano T. Plant Nutrition for Sustainable Food Production and Environment. Trends Sci. 1998, 3 (1), 75–77. 10.5363/tits.3.75. [DOI] [Google Scholar]
  61. Government of Canada. Cannabis Regulations. Justice Laws Website. https://laws-lois.justice.gc.ca/PDF/SOR-2018-144.pdf.
  62. Government of Canada. Canadian Cannabis Survey 2023, Summary. Cannabis research and data. https://www.canada.ca/en/health-canada/services/drugs-medication/cannabis/research-data/canadian-cannabis-survey-2023-summary.html.
  63. Statistics Canada . Control and sale of alcoholic beverages and cannabis, April 1, 2021 to March 31, 2022. Government of Canada, https://www150.statcan.gc.ca/n1/daily-quotidien/230224/dq230224a-eng.htm (accessed 2023–04–17).; Gruda N. S. Increasing Sustainability of Growing Media Constituents and Stand-Alone Substrates in Soilless Culture Systems. Agronomy 2019, 9 (6), 1–24. 10.3390/agronomy9060298. [DOI] [Google Scholar]
  64. Zafeiridou M.; Hopkinson N. S.; Voulvoulis N. Cigarette Smoking: An Assessment of Tobacco’s Global Environmental Footprint Across Its Entire Supply Chain. Environ. Sci. Technol. 2018, 52 (15), 8087–8094. 10.1021/acs.est.8b01533. [DOI] [PubMed] [Google Scholar]
  65. Stoessel F.; Juraske R.; Pfister S.; Hellweg S. Life Cycle Inventory and Carbon and Water FoodPrint of Fruits and Vegetables: Application to a Swiss Retailer. Environ. Sci. Technol. 2012, 46 (6), 3253–3262. 10.1021/es2030577. [DOI] [PMC free article] [PubMed] [Google Scholar]
  66. Heller M. C.; Keoleian G. A. Greenhouse Gas Emission Estimates of U.S. Dietary Choices and Food Loss. J. Ind. Ecol. 2015, 19 (3), 391–401. 10.1111/jiec.12174. [DOI] [Google Scholar]
  67. Muñoz P.; Antón A.; Nuñez M.; Paranjpe A.; Ariño J.; Castells X.; Montero J. I.; Rieradevall J. Comparing the Environmental Impacts of Greenhouse Versus Open-field Tomato Production in the Mediterranean Region. Acta Hortic. 2008, 801, 1591–1596. 10.17660/ActaHortic.2008.801.197. [DOI] [Google Scholar]
  68. Neto B.; Dias A. C.; Machado M. Life Cycle Assessment of the Supply Chain of a Portuguese Wine: From Viticulture to Distribution. Int. J. Life Cycle Assess. 2013, 18 (3), 590–602. 10.1007/s11367-012-0518-4. [DOI] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

as4c00054_si_001.pdf (172.7KB, pdf)

Articles from ACS Agricultural Science & Technology are provided here courtesy of American Chemical Society

RESOURCES