By Dr. Fatemeh Etemadi
Our water, air and land are being polluted more than ever by textile manufacturing byproducts and plastic microparticles. With industrial hemp’s resurgence as a cash crop and ability to integrate into regenerative farming practices, hemp might be the answer to our problems.
Hemp grows rapidly and has an extensive root system, making it a potential tool for natural weed suppression and enhancing soil health. Weed management is considered a perennial obstacle for existing organic farmers and a barrier for those considering transitioning to organic. Successful weed management in organic systems often includes intensive tillage and repeated cultivation that can degrade soil health. As a cover crop, hemp enhances soil health by shading out weeds, reducing the need for synthetic herbicides.
Hemp, as a multipurpose crop, is environmentally friendly, can increase farmer income, is nutritious when consumed, and has many uses in agriculture and industry. As industrial hemp can be a good option in the transition to sustainable agriculture, Rodale Institute has conducted several experiments to gather crucial information to help farmers succeed and to examine hemp as a tool for regenerative farming.
In 2017, Rodale Institute initiated a four-year trial studying the effects of industrial hemp as part of a regenerative organic crop rotation to enhance soil health, increase crop production, weed suppression, and improve organic fertility management when growing hemp in Pennsylvania. Subsequent trials added to this study include analysis of nutrient management, planting dates and CBD varieties. The overall goal of Rodale Institute’s research into industrial hemp is to estimate the potential for this crop to improve farmer success in a regenerative organic system.
The rotational research trial results indicated that hemp is a viable weed suppression cover crop that has higher economic value than something like sorghum Sudangrass, typically used as a forage for livestock. This may provide potential to reduce tillage in organic systems.
Soybean and wheat yields following hemp remained relatively high compared to other production systems on the Rodale Institute farm in Pennsylvania — often reaching or exceeding national averages.
In the nutrient management trial, we learned that hemp grain yield is increased with increased nitrogen fertilizer application. Sufficient nitrogen availability allows hemp to maximize growth and outcompete weeds at smaller between-row spacings (7.5 inch), while weed species outcompeted hemp in larger row spacings (15 inch) when nitrogen is limited.
In CBD varieties, CBD concentrations were highest with the application of straw and compost compared to black plastic mulch and bloodmeal (12-0-0) applied as fertilizer; however, plant height, width, branch number and biomass were highest in plants with bloodmeal and plastic mulch, resulting in higher total CBD yield. There appears to be tradeoffs between mulching types, increased nitrogen fertility, plant production and CBD concentration. Future research should continue to optimize spacing, fertility and mulching needs.
Since the launch of the Rodale Institute industrial hemp research program in 2017, public interest in our work has grown rapidly. In addition to attending conferences and meetings, Rodale Institute staff consult with farmers regularly across the Northeast and entire United States on growing industrial hemp in a regenerative way to determine how hemp can benefit farmers while mitigating environmental impacts.
In 2021, the hemp research program will begin to transition more research trials to the Pocono Organics site in Long Pond, Pennsylvania, and will include continued analysis of nutrient management, cover crops, reduced tillage and a selection of auto-flowering varieties for regenerative organic hemp production. Also, the Institute plans to test more varieties, specifically domestic varieties as they become available, and adjust planting date, harvest date, seeding rate, and spacing to maximize the marketability of the varieties for their intended use. This research helps us learn how to increase farmer income, learn more about seed and dual-purpose varieties and determine if they can fit into a grain rotation as a weed smother crop.
To learn more about Rodale Institute work on industrial hemp, visit RodaleInstitute.org/IndustrialHemp.
Dr. Fatemeh Etemadi is Rodale Institute’s Post-Doctoral Research Associate in Industrial Hemp. Fatemeh is a Ph.D. graduate from University of Massachusetts, Amherst, with the concentration in agronomy and crop physiology. Fatemeh works on Rodale Institute’s Industrial hemp research. Contact Fatemeh at Fatemeh.Etemadi@RodaleInstitute.org.