2018 ASHS Annual Conference

Industrial hemp, a versatile plant grown for its fiber, seed or oil, was a valuable cash crop and a major industry in Pennsylvania for more than 260 years prior to its ban in 1933. Due to its close relationship to the marijuana plant, hemp production became a casualty of a 1933 law banning marijuana, and was later named a Schedule 1 drug by the Controlled Substances Act of 1970. In 2017, Rodale Institute was one of 16 organizations that received a permit for the inaugural planting of hemp in Pennsylvania in more than 80 years as part of the Pennsylvania Department of Agriculture Industrial Hemp Pilot Program. A four-year research project was initiated to evaluate industrial hemp varieties that are most suited to soil and climatic conditions in Pennsylvania. Organic farmers are interested in growing hemp but require research-based information that will help them make informed decisions about integrating hemp into their rotations. The project has two components; – a variety trial that aims to determine available varieties with greatest seed yield and fiber content and a weed suppression trial that aims to establish hemp as a dual cover and cash crop. Three varieties are being assessed for weed suppression, viability, height, hemp biomass, seed yield and effect on soil physical and chemical properties. The weed competition trial is evaluating potential of hemp to act as a substitute cover crop in common organic tilled and no-till crop rotations, as a weed suppression cover crop. Preliminary results indicate that both ‘Santhica’ hemp variety and sorghum Sudan grass equally suppress weeds compared to control. The data indicate that hemp suppresses ragweed better than Sudan grass, while the latter suppresses lambsquarters better than hemp. Data also suggest that ‘Santhica’ hemp and Sudan grass reduce soil bulk density. After nearly 80 years, there are encouraging signs that industrial hemp may soon be legal to grow again in the United States. However, the knowledge needed to grow hemp has largely been lost. Our research will help growers make informed decisions and avoid costly mistakes when hemp is legalized.