Initial insights into sunn hemp–corn intercropping for forage production and nitrogen reduction

Corn ( Zea mays ) is a globally important crop to produce grain and silage for livestock systems. However, corn generally requires high levels of nitrogen (N) fertilizer. Introducing sunn hemp ( Crotalaria juncea L.; SH), an annual legume, is a potential option for reducing N inputs. This study aimed to evaluate initial insights of herbage accumulation (HA), nitrogen biological fixation, and nitrogen use efficiency (NUE) using SH intercropped with corn in two locations, Marianna, FL, and Marshfield, WI. Treatments were SH monoculture, corn without N‐fertilizer (Corn − N), N‐fertilized corn (Corn + N), corn and SH planted on the same day (Corn + SH0), and corn and SH planted 4 weeks later (Corn + SH4). Corn + N had greater HA at both sites. The treatment SH fixed 87 kg N ha −1 and had a greater %N derived from the atmosphere (%Ndfa) in Marianna (71.4%). N yield was greater for Corn + N in both sites, and no difference was found between the intercropped treatments. Corn + SH0 in Marianna and Corn + SH4 in Marshfield resulted in great NUE (72% and 69%, respectively). The data indicate that intercropping corn and SH can enhance NUE. However, intercropping corn and SH reduces the overall HA, which requires further evaluation to promote producer adoption of these systems.