Of the thousands of applications for the hemp plant, from bio-based fuels to food products, none presents more of an interesting application than to utilize hemp as a phytoremediation crop, including radioactive materials in the soils. The use of hemp to cleanse the soil presents a cutting-edge incorporation of a plant that is so versatile. Scientific evidence as to the efficacy of hemp as a phytoremediation material is increasing.
However, before we discuss the potential for hemp as an environmental cleanup material, it is important to first understand the term ‘phytoremediation’. “Phytoremediation [is] the use of green plants to treat and control wastes in water, soil, and air…[and] is an important part of the new field of ecological engineering” (S.C. McCutcheon, S.E. Jørgensen, in Encyclopedia of Ecology, 2008). More simply understood, phytoremediation is the ‘absorbing’ or ‘removal’ of contaminants from the environmental to isolate it for proper disposal, thereby providing a cleaner, safer environment.
So, where does hemp as a plant fit in the phytoremediation conversation?
Mounting evidence suggests that the natural ability of hemp to absorb/filter toxic materials from soil, as well as water and air make it an ideal plant for such use. In fact, one of the worst environmental disasters to ever occur, the 1986 Chernobyl Nuclear Disaster in the former Soviet Union (now Ukraine), is one of the early examples of the emerging potential for hemp as an excellent phytoremediator to clean up radioactive material (and other toxins). While this is an extreme example that illustrates the potential for hemp, more practical applications for general use are as a rotation crop on agricultural land to remove phosphate fertilizers, a major contributor of the increase of Cadmium (Cd) in the soil, and pesticides build-up. This would have a multi-fold benefit for farmers. First, use of hemp to cleanse the soil would improve the quality of crops and the health of consumers. Second, the ability to clean up unusable acreage would enable farmers to expand their farming activities. Third, by incorporating hemp as, at least, a rotational crop, provides a potential add-on high-value cash crop.
Hemp is not the exclusive plant for phytoremediation; however, it is the top tier plant. Why?
To be an effective phytoremediator, the plant itself must be able to address contamination in more than the top layer of soil, which requires a root system that goes deeper than typical plants. This is what makes hemp a top-tier candidate for phytoremediation. Hemp roots range from 1.5 feet to 3 feet in length. “This makes it attractive because hemp is able to reach deep into the soil and therefore be much more effective at removing widespread contamination” (Citterio, 2003). Another key attribute is that contaminants are absorbed into every facet of the plant, from the roots to the stalk and leaf of the plant.
The upside benefit is that once hemp is deployed as a phytoremediator and has completed its task, it has potential for use afterward. While that use would obviously not involve processing it for foods, clothing, or other consumer products, the ability to process the hemp plant into bioenergy products, including fuels, and for thermal conversion for power generation.
As the science behind phytoremediation continues to increase, the potential of hemp as a top phytoremediator will continue to be proven an effective vehicle for not only farmers but also for industries faced with greater environmental protection requirements to ensure less damage from its activities are incurred.