The Agro-Ecological Value of Industrial Hemp: A Sustainable Solution for Modern Agriculture

Cannabis, particularly hemp, is increasingly recognised as a valuable crop for both commercial and small-scale agricultural cultivation due to its extensive interactions within agri-ecosystems. These interactions support biodiversity and offer potential for ecological sustainability. 

However, as noted by O’Brien and Arathi (2019:1), cannabis is still a “relatively new crop under scientific enquiry,” meaning its full ecological value remains underexplored. Aliferis and Bernard-Perron (2020) introduced the term “Cannabinomics,” reflecting the emerging and dynamic nature of the cannabis industry, which promises significant economic and ecological impact.

1. Supporting pollinating ecosystem agents

Pollination is a cornerstone of thriving agri-ecosystems, ensuring the reproduction of over 75% of flowering plants, including key crops. South Africa’s unique Afrotropical bee species, such as Apis mellifera capensis (Cape honey bee) and Apis mellifera scutellata (African honey bee), are essential pollinators that require consistent pollen sources to maintain their immune systems and pathogen resistance.

Although hemp lacks nectar, male hemp plants provide abundant pollen, which serves as a crucial nutrient source for honey bees, other pollinating bees, and various pollinating agents (Flicker, Poveda, and Grab, 2019; O’Brien and Arathi, 2019). Male hemp plants, which grow taller than female plants, release significant quantities of pollen for up to six or seven weeks. The height and temporal flowering of these male plants directly influence bee species richness and abundance.

Studies conducted in New York and Colorado have shown that hemp pollen can fill gaps in pollen availability when other crops are not flowering, supporting the biodiversity of Hymenoptera (Flicker et al., 2019; O’Brien and Arathi, 2019). 

Integrating hemp strategically within South Africa’s agricultural regions could mitigate seasonal pollen scarcity and provide essential ecosystem services. This approach can also serve as an additional income source for hemp farmers.

How hemp supports pollinators

• Anemophilous pollination: Hemp is wind-pollinated, producing abundant pollen that supplements the diets of bees, particularly during pollen-scarce periods. 
• Pollen availability: Male hemp plants release pollen over an extended period (up to 6-7 weeks), filling seasonal pollen gaps and supporting bee health.
• Plant height & diversity: The height of hemp plants (ranging from 1.5m to 4m) correlates with increased diversity and abundance of pollinator species. Taller hemp varieties provide more extensive pollen sources, supporting a broader range of pollinators.
• Pollen integration: Hemp pollen acts as a functional complementary plant within agri-ecosystems, aiding in honeybee immune support and reducing pathogen susceptibility.

In a world where pollinator populations are under threat, integrating industrial hemp into crop rotations can serve as a reliable pollen source, promoting healthier bee communities and enhancing agricultural productivity.

2. Restoring soil health

Industrial hemp is a powerful ally in regenerating and stabilising degraded soils. Its robust root system, high biomass yield, and stress-tolerant genetics make it ideal for phytoremediation (the process of using plants to decontaminate soil). By “cleaning” the soil through the absorption of contaminants, hemp supports healthier crop rotations and enhances soil productivity.

Hemp’s ability to hyperaccumulate heavy metals was demonstrated in a 1998 Ukrainian study addressing contamination near Chernobyl (Ahmad et al., 2015). This characteristic shows promise for restoring abandoned mine sites and degraded soils in South Africa, including the Eastern Cape.

Cannabis also contains natural chemical constituents that function as herbicides. This reduces the need for synthetic pesticides, benefiting indigenous insect populations and overall ecosystem health.

Key bioremediation benefits

• Stress-tolerant genes: Hemp’s resistance to soil contaminants is facilitated by heavy metal-responsive genes like Glutathione-Disulfide Reductase (GSR) and Phospholipase D-A (PLDA).
• Fast growth cycle: With a life cycle of just 180 days, hemp can quickly restore soil health, improving edaphic (soil-related) properties and nematode resistance.
• Heavy metal absorption: Hemp can absorb toxic metals like copper, cadmium, and lead, making it a valuable tool for rehabilitating mining sites and polluted farmlands.
• Improved soil performance: After hemp remediation, soils exhibit increased fertility and reduced toxicity, benefiting subsequent crops and ensuring long-term agricultural sustainability.

3. Carbon sequestration to help combat climate change

In an era of escalating greenhouse gas emissions, hemp offers an ecologically significant solution for carbon sequestration. By absorbing and storing carbon dioxide (CO₂), hemp can help offset the carbon footprint of agricultural and industrial processes.

According to Vosper (2019), one hectare of industrial hemp can absorb up to 22 tonnes of carbon dioxide. This capacity for carbon sequestration positions hemp cultivation as a strategic approach to offset emissions and meet South Africa’s carbon reduction targets. Hemp offcuts can also be repurposed for animal feed or bedding, ensuring minimal waste.

Carbon sequestration potential

• High carbon absorption: One hectare of hemp can absorb up to 22 tonnes of CO₂ during a single growing season, depending on agronomic practices like sowing density.
• Carbon trading opportunities: Integrating hemp into farming practices can provide opportunities for carbon credits, helping reduce anthropogenic greenhouse gas emissions and promoting sustainable resource management.
• Deep root systems: Hemp’s extensive root system helps store carbon in the soil, contributing to long-term carbon sequestration.

4. Enhancing agro-ecosystem management

Healthy agro-ecosystems are essential for sustainable food production and biodiversity preservation. Industrial hemp contributes to agro-ecosystem management through its beneficial interactions with soil, pollinators, and the broader environment.

Key contributions of hemp

• Soil enrichment: Hemp’s tap root system improves soil structure, prevents erosion, and promotes nutrient cycling.
• Biodiversity support: By providing pollen for diverse pollinator species, hemp enhances overall ecosystem resilience.
• Complementary crop: Hemp can be integrated with other crops to create diverse, resilient farming systems, reducing reliance on chemical fertilizers and pesticides.

5. Revenue generation through hemp products

Hemp offers various avenues for income beyond its agricultural benefits, adding value to farm operations.

• • Bioremediated soil: This does not make the farmer money but essentially reduces farmer costs by decreasing the total cost of inputs (fertiliser) into the next crop rotational planting.
  • Byproducts for livestock: Hemp biomass can be repurposed for animal feed or bedding, ensuring minimal waste and providing another income source.
  • Textiles, biofuels, and more: Hemp’s versatility extends beyond agriculture. Its fibres can be used in textiles, building materials, and biofuels, offering farmers multiple markets for hemp products.

South Africa’s path to sustainable growth and green prosperity

As research into “Cannabinomics” continues, the dynamic cannabis industry is poised to play a critical role in ecological and economic sustainability. South Africa has the opportunity to lead the way in integrating this sustainable crop into its agricultural systems, benefiting both the environment and local communities.