As the Central Valley nears the end of yet another dry winter, farmers around the region have water on the mind with irrigation season looming. While the area’s largest agribusiness operations include fruit, nut and vegetable crops, marijuana is the state’s newest cash crop, and its cultivators are looking to conserve water when growing the in-demand plant.
Estimations from the Journal of Bioscience state that, on average, a one-acre outdoor cannabis crop requires 457,600 gallons of water per year, or about 1.4 acre feet of water. Though it sounds high, cannabis falls in the mid- to low-range compared to some of California’s other crops.
Alfalfa, for example, requires about 5.2 acre feet of water, while almonds call for 3.8 acre feet.
Local governments throughout the state have permitted thousands of indoor and outdoor marijuana farms since recreational grows became legal on Jan. 1 – Stanislaus County alone received 265 Commercial Cannabis Permit applications, and approved 61 of them – even though state regulators are unsure how much water the new industry will consume.
Representatives from both Turlock Irrigation District and Modesto Irrigation District stated that their respective irrigation seasons will move forward as planned, with no adjustments being made for the new marijuana crops popping up around the area.
Darron Silva of JDI Farms, who owns a marijuana dispensary in Modesto and manages a grow operation in Patterson, has grown cannabis for about 15 years, he said. His crop in Patterson consists of a 22,000 square foot grow which contains a cluster of greenhouses, each 2,840 square feet. There are 620 plants in each greenhouse, but how much water each plant needs depends on the season, said Silva.
“You give the plant one gallon of water per 10 gallons of soil, so for a 20-gallon pot of soil, you would need to give the plant two gallons every time you water it,” said Silva. “In the summer, you water every other day or every day, depending on the weather, and in the winter you’re watering twice, maybe once a week because the humidity levels are higher and the plants don’t dry out as fast.”
That means that in the summer, just one of Silva’s greenhouses can consume up to 1,240 gallons of water per day and the same amount can be consumed by a plant over the course of a week in the winter.
To keep his crop’s water consumption low, Silva has taken conservative measures when deciding what kind of system to use. Every plant is watered by using a drip system which can be customized for each individual plant, and uses water that has been run through a strict reverse osmosis system. This filtration method removes dissolved salts in the water that Silva uses, which he procures from a well on the property.
Silva, like many almond farmers in the area, switched from flood irrigating to a drip irrigation system for his crops when the drought in California first began. Drip irrigation systems can reduce water use by up to 40 percent compared to flood irrigation, cutting costs for cultivators and conserving water.
Should the water received during last year’s record-setting rainy season once again prove to be the last the state sees for a while, Silva’s conservation efforts to date have prepared him, he said. Other measures Silva has taken include raised soil beds and amendments to that soil, such as the placement of beneficial microbes which decrease the amount of watering necessary for a plant.
“It is a worry – we’re always concerned about there not being enough water,” he said. “We’re seeing throughout the marijuana growing practice that a lot of people are going into water conservation mode and installing drip systems.
“In preparation for future droughts, we wanted to be in that conservation mode.”