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From Soil to Stone Wool: The growing trend of alternative media in cannabis cultivation

AgTech, conservationists and multiple levels of government are sounding the alarm about the importance of soil health. In fact, the U.S. House Committee on Agriculture held a hearing last fall on the very subject. Stakeholders from across the agriculture and conservation sectors convened to discuss the latest research and initiatives on facilitating soil health. Due to federal prohibition, cannabis operators were not included in that conversation — but they should definitely be paying attention.

One particular cultivation practice, hydroponic growing, promotes soil health by entirely removing soil from the equation. Hydroponics utilize inert growing media in place of soil and reduce water and pesticide use compared to soil-based systems.

A hydroponic grow, whether the crop is tomatoes or cannabis, requires only water, a container, nutrients, anchors, light sources and alternative growing media like stone wool.

While hydroponics is still an evolving methodology in commercial vegetable production, the use of inert growing media for hydroponics has been well-developed in the cannabis sector. For growers that keep costs and public sentiment top of mind, hydroponics are here to assist.

Water conservation

The energy and water usage of cannabis has become a well-documented concern as state regulatory programs mature. Documenting usage and investing in technologies that can grow more with less are paramount to reducing the footprint of this emerging industry.

Substrates like stone wool that absorb predictable amounts of inputs like fertilizer and water can save on utility expenditures in the short term. They may also protect against adverse regulatory shifts in the long term if governments mandate reduced use of inputs like fertilizer and water.

If and when Congress, and subsequently federal agencies, expand regulatory oversight to cannabis, the federal government could be compelled to implement water restrictions to address environmental issues commonly associated with cannabis cultivation. To understand the potential consequences, look at protests by Dutch farmers in 2022 over new emissions standards that forced radical changes in a tight timeframe.

Indeed, soil health is intricately connected to other sustainability concerns like water quality. Not only are non-particulate substrates growing in popularity, so are water reclamation and filtration systems. Many legal states are already offering cannabis growers rebates on more efficient systems such as LED lights, incentivizing a shift away from the hot, energy-hungry HIDs that have long been an industry staple.

It stands to reason that both water and soil health will join energy efficiency as regulatory priorities.

Sustainably sourced

Another, more topical benefit to inert substrates such as stone wool is that, because they’re typically made of processed basalt, they entirely bypass the matter of soil purity. There is no soil in hydroponic substrates to contaminate a consumable crop — and likewise, the environmental impacts are greatly lessened with this type of growing media.

Further, with growing federal concerns about the levels of heavy metals and “forever chemicals” called PFAS contaminating ecosystems and causing adverse health effects, agricultural commodity producers have little time to waste. A study by Healthy Babies, Bright Futures (HBBF) found that 94% of tested baby foods, family meals, and homemade purees had “detectable amounts of one or more heavy metals.”

While organic shopping cannot guarantee lower exposure to these chemicals, foods grown hydroponically could limit exposure to heavy metals and PFAS in soil since they do not appear in the materials used to produce stone wool.

As the agriculture and cannabis industries and consumer advocates continue to examine methods of growing, the demand for alternative sustainability measures in these industries will increase—particularly in drought-riddled Western states and states with newly legalized cannabis markets.

Proactivity about soil health equates to proactivity about building a greener cannabis industry overall.

A greener cannabis industry protects producers’ success and longevity. Investing in growing techniques that prioritize soil health means investing in public health, too. Proactively upgrading to more sustainable equipment selections sooner rather than later is one way cannabis producers can protect their bottom line while researchers and regulators determine best practices for the future of soil health.

Madison Walker is Head of Public Affairs for North America at Grodan, a global leader in precision growing solutions and inventor of stone wool cultivation. She is responsible for the development and implementation of Good Manufacturing Practices and Good Production Practices protocols for the United States, Canada, and International markets. 

To learn more about how their products contribute to a more sustainable agricultural industry, see their blog and podcast.