Effect of row spacing, nitrogen, and varieties on industrial hemp production in Missouri

Production of industrial hemp ( Cannabis sativa L.) started since the passage of the Agricultural Act of 2014, Public Law 113–79. In Missouri, industrial hemp cultivation started after the 2018 Farm Bill and the Missouri Senate Bill 133 in 2019. Preliminary research was started in 2019 at the Graves-Chappel Extension and Education Center near Rock Port, Missouri, and Lee Greenley Jr. Memorial Research Farm near Novelty, Missouri to evaluate row spacing (19 and 76 cm), nitrogen (N) rates (0, 56, 112, 168, and 224 kg N ha −1 ), and industrial hemp varieties to provide agronomic recommendations. A narrow row spacing (19 cm) increased grain and biomass yield compared to wide row spacing (76 cm). In 2019, grain yield varied from 429 to 628 kg ha −1 in narrow rows and 175–475 kg ha −1 in wide rows at a later planting date, while it varied from 1289 to 1598 kg ha −1 in narrow rows and 1345–1553 kg ha −1 in wide rows in 2020 at an earlier planting date. A similar response was observed for biomass. No significant effect of N rates was observed in northwest Missouri on a highly fertile river bottom soil. Industrial hemp biomass and grain production varied significantly among varieties tested in 2022. The biomass yield ranged from 1343 to 13,696 kg ha −1 while grain yield varied from 255 to 1965 kg ha −1 . Initial findings showed that cultivar selection, row spacing, and weed management observations were important factors affecting industrial hemp production and needed additional research in Missouri.