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Table 1 Water demand comparison between Cannabis and commodity crops

From: A narrative review on environmental impacts of cannabis cultivation

Plants Total growing period (days) Water demand per season
(million gallons acre−1)
Daily water demand
(gallon ft−2 day−1)
Ref
Cannabis: outdoor 150 1.57 a 0.24 (HGA, 2010)
Cannabis: outdoor August n.a 0.22 (Wilson et al., 2019)
Cannabis: outdoor September n.a 0.17 (Wilson et al., 2019)
Cannabis: indoor August n.a 0.18 (Wilson et al., 2019)
Cannabis: indoor September n.a 0.22 (Wilson et al., 2019)
Cotton 180–195 0.75–1.39b 0.09–0.15 (Brouwer and Heibloem, 1986)
Cotton / / 0.14–0.17 (Hussain et al., 2020)
Maize 130–150 0.53–0.86b 0.07–0.13 (Brouwer and Heibloem, 1986)
Corn / / 0.22 (peak) (Rogers et al. 2017)
Soybean 135–150 0.48–0.75b 0.07–0.13 (Brouwer and Heibloem, 1986)
Soybean / / 0.22 (peak) (Rogers et al. 2017)
Wheat 120–150 0.48–0.69b 0.07–0.19 (Brouwer and Heibloem, 1986)
Wheat / / 0.19 (peak) (Rogers et al. 2017)
Rice 90–150 0.48–0.75b 0.09–0.18 (Brouwer and Heibloem, 1986)
Rice / / 0.11–0.15 (Intaboot, 2017)
  1. Notea: The water demand of cannabis is calculated based on 22.7 l (6 gallons) of water per day during the growing season and 200 plants per 5,000 sq. ft (HGA, 2010)
  2. Noteb: The water demand of crops is based on crop water need from Table 14 in Brouwer Heibloem (Brouwer and Heibloem, 1986). We convert the unit from mm to million gallon acre−1 according to the rule of unit conversion where 1 acre inch is equivalent to 27,154.29 gallon