Abstract Research on industrial hemp ( Cannabis sativa L.; < 0.3% ∆‐9‐total tetrahydrocannabinol) has been limited due to legal restrictions on its cultivation. However, changes in government policies have sparked renewed interest in exploring the agronomic aspects of hemp cultivation. Further, increased regulations on fertilizer applications in Florida have necessitated investigating location‐specific nutrient management practices of industrial hemp. This 3‐year study assessed the effect of six nitrogen (N) rates (urea 46‐0‐0 at 0, 56, 112, 168, 224, and 280 kg N ha −1 ) and two cultivars (New West Genetics NWG‐2730 and IND Hemp IH Williams) under a 6 × 2 factorial in randomized complete block design with four replications. The study observed a 27% and 32% increase in aboveground biomass and stem biomass, respectively, with an increase in N rate from 0 to 168 kg ha −1 . Significant cultivar effects were found in emergence stand count, stand count at harvest, plant height, stem biomass, and total aboveground biomass. Cultivar IH Williams resulted in 22%, 38%, and 41% higher emergence stand count, stem biomass, and total aboveground biomass, respectively, than NWG‐2730. There was significant interaction between the N rate × year for stem diameter and cultivar × year for stand count at harvest, plant height, stem biomass, and total aboveground biomass, indicating that the effect of N and cultivar on the growth and biomass yield of industrial hemp was soil and weather dependent. Based on the best‐fit linear plateau model, we conclude that the optimal N rate for fiber hemp in Florida is 147 kg N ha −1 , as there was no significant increase in fiber hemp yields at higher N rates.
Nwosu et al. (Sun,) studied this question.