Nutrient uptake and partitioning of industrial hemp in the central Plains

Abstract Hemp ( Cannabis sativa L.) production was either illegal or highly regulated in the United States for most of the 20th century. The relaxation of regulations and development of fiber, grain, and cannabinoid markets since the turn of the 21st century has created the need for production information, including the fertility requirements of the crop. A series of experiments was conducted over 3 years at three Kansas locations to assess biomass production and nutrient uptake of fiber and hemp cultivars in seven environments representing a range of growing conditions in the central Great Plains. Nutrient uptake increased as biomass production increased across the range of 1.7–9.8 Mg ha −1 in these experiments ( R 2 = 0.41–0.86). Peak biomass production and uptake of potassium, calcium, and sulfur were greater for the fiber cultivar than for the grain cultivar. However, uptake of the remaining nutrients did not differ between cultivar types. Peak macronutrient uptake reached 180, 22, and 173 kg ha −1 of nitrogen, phosphorus, and potassium, respectively. Secondary nutrient uptake reached 153, 27, and 16 kg ha −1 of calcium, magnesium, and sulfur, respectively. Micronutrient uptake reached 82, 1126, 856, and 272 g ha −1 of copper, iron, manganese, and zinc, respectively. Although dry matter and nutrient partitioning differed between fiber and grain cultivars, cultivar types did not differ in potential export (stalk + seed) of dry biomass and most nutrients. Nutrient management should differ for fiber versus grain production but may be similar for dual‐purpose production systems.