Short‐term agronomic consequences of industrial hemp incorporation into traditional corn–soybean rotations

Abstract Kentucky producers have sought to add industrial hemp ( Cannabis sativa L.) for grain, fiber, and/or floral material to their cropping systems since hemp's legalization in the 2018 Farm Bill. This study sought to quantify hemp's impact on ecosystem services provisioned by the traditional corn ( Zea mays L.)–soybean ( Glycine max (L.) Merr.) rotation. We hypothesized that hemp incorporation would diversify crop rotations and positively impact ecosystem services, such as soil nutrient retention and crop yield. This study was conducted at the University of Kentucky North Farm (Lexington, KY) and consisted of six crop rotation treatments in a randomized complete block design with five replications. Cash crop aboveground biomass and yield were quantified at harvest, and belowground biomass was measured by collecting root cores within 2 weeks of harvest. Cover crop wheat ( Triticum aestivum L.) aboveground and belowground biomass was measured to evaluate impact on the successive crop. Soil samples were collected before and at completion of the 3‐year rotation to quantify soil health impacts. Aboveground and belowground biomass of cash and cover crops were unaffected by hemp's inclusion. Similar results were found for most soil health metrics, including nutrient availability. Grain biomass and fiber hemp root biomass in this study were small (∼4x less than corn) and most comparable to soybean. Overall, this study found that inclusion of industrial hemp does not negatively impact ecosystem services in the short term; however, long‐term effects may arise given differences in root biomass and nutrient return via retting compared to traditional cash crops.