Industrial Hemp Response to Nitrogen, Phosphorus, and Potassium Fertilization

Industrial hemp (Cannabis sativa L.) production has increased in Canada in recent years, and interest for this multipurpose crop remains high. The lack of agronomic guidelines for Eastern Canada represents, however, a limiting factor for local hemp production. This study assessed biomass and seed yields and composition of two hemp cultivars (CRS-1 and Anka), following various N, P, and K fertilization treatments (0, 50, 100, 150, and 200 kg N or K ha(-1); 0, 25, 50, 75, and 100 kg P ha(-1)). The experiment was conducted in multiple environments in the province of Quebec. Positive linear and quadratic responses of biomass yield, seed yield, and seed crude protein concentration to N fertilization were observed in all environments; the magnitude of the response depended, however, on the environment and cultivar. Across environments and cultivars, biomass and seed yields increased from 1674 to 4209 kg ha(-1) and from 519 to 1340 kg ha(-1), respectively, with the application of 200 kg N ha(-1) when compared with the unfertilized control. Nitrogen fertilization affected biomass cellulose and hemicellulose concentrations, but the overall response remained minimal. Phosphorus and potassium fertilizations had very limited effect on biomass and seed yields and composition in all environments. In conclusion, while industrial hemp responded to N fertilization up to 200 kg N ha(-1), response to P and K fertilization remained limited.