NITROGEN FERTILIZATION IMPACT ON HEMP ( CANNABIS SATIVA L.) CROP PRODUCTION: A REVIEW

Regained interest in hemp cultivation has created opportunities and challenges, especially regarding crop management, for example, fertilizer application rate. Most of the literature on nitrogen (N) management in hemp production is from Asia and Europe, with more established cropping systems than in North America. Through our review, we found evidence that N fertilizer has a noticeable positive impact on basic crop morphology and physiology parameters, or at least the crop responds to such infield fertilizer applications. Some physiological parameters that show positive response include photosynthetic pigments, N and nitrate concentration, and water use efficiency. N fertilizer has been demonstrated to increase stem and fiber yield but reduce fiber quality. Increasing N also appears to increase seed yield and protein content. Both excess and low rates of N fertilizer are detrimental to floral hemp. There is little evidence that Δ9‐tetrahydrocannabinol concentration is more affected by N fertilization than genetics. The impact of fertilizer source and timing remains a critical area for research. There is still a need for research on developing a sustainable nutrient management program for hemp.