Response of cannabidiol hemp (Cannabis sativa L.) varieties grown in the southeastern United States to nitrogen fertilization

Abstract

With the expanding hemp cannabidiol (CBD) industry in the United States, information on fertilizer recommendations for optimal production under field conditions is deficient in the literature. This study evaluates the effects of nitrogen (N) fertilization on bud biomass and CBD yield of two high-yielding CBD hemp varieties (Spectrum and Therapy) under field conditions. Four application rates of N fertilization (0, 56, 112, and 224 kg N ha-1) were supplied using 2 commercially available N fertilizers. Fresh bud biomass, dry bud biomass, and CBD yield (g plant-1) increased quadratically with N fertilization rates, with optimum rates between 140 and 190 kg N ha-1. When pooled across varieties, the tissue N concentration was linearly related to the fresh bud biomass, dry bud biomass, and CBD yield. Our findings show that N fertilization can affect CBD yield under field conditions. The resulting effect of N fertilizer rates on these varieties could serve as a preliminary guide for CBD hemp production under field conditions, although results may differ with variety, location, or fertilizer type.