Effect of Nitrogen Fertilizer Application Timing and Herbicide on Industrial Hemp.

A field experiment was established in 2017 in Bowling Green, KY to evaluate various nitrogen fertilizer application timings on the growth and yield of industrial hemp (Cannabis sativa). The study utilized a split plot design with 157 kg ha^-1 nitrogen fertilizer applied at 3 timings (at plot establishment, side-dressed, and 78 kg ha^-1 at establishment plus 78 kg ha^-1 side-dressed); a control treatment was included and each treatment was replicated 4 times. Industrial hemp was seeded at a rate of 43 kg ha^-1 on June 2^nd into a conventionally tilled silt loam soil. Half of each treated plot was sprayed with pendimethalin herbicide at a rate of 2.8 L ha^-1 the day after seeding. Data collected included stand counts at 34 days after planting (DAP), plant heights at 34 and 55 DAP, and stand counts, plant heights, above-ground biomass, and seed yield at harvest (89 DAP). Herbicide application reduced stand count and plant height 34 DAP but did not reduce height 55 DAP or at harvest. Herbicide did not reduce above-ground biomass but did reduce seed yield. Nitrogen application timing did not influence stand count, biomass or seed yield but did influence plant height early in the growing season.