Abstract Winter cereal rye ( Secale cereale ) (WCR) is widely used in the US Midwest, to reduce nitrate‐N (NO 3 ‐N) and phosphorus losses. However, its adoption before corn ( Zea mays L.) has been limited by concerns over N immobilization and yield penalty. This study evaluated the effects of WCR seeding rate (Study A) and cultivar by seeding rate interaction (Study B) on biomass, composition, corn growth, yield, and soil N dynamics. Study A included a no‐cover crop control (NOCC) and four WCR seeding rates (34, 56, 84, and 112 kg ha −1 ) in a randomized complete block design (RCBD) with six replicates. Study B tested two WCR cultivars (Guardian widely used cultivar vs. hybrid rye) at two seeding rates (67 and 101 kg ha −1 ) in a factorial RCBD with four replicates. Results of Study A indicated that increasing seeding rate led to greater WCR biomass and carbon:N ratio without affecting N uptake. However, higher seeding rates (≥67 kg ha − 1 ) reduced corn stand count and yield in one of 2 years. In Study B, hybrid rye produced more biomass than Guardian, while final corn stand count declined in all WCR treatments compared to NOCC. Soil NO 3 ‐N with WCR was lower than NOCC, suggesting reduced leaching potential during fallow period. We conclude that seeding rates below 67 kg ha −1 minimized yield impacts, with rates as low as 34 kg ha −1 provided similar agronomic benefits. Future research should address tradeoffs in weed suppression, nitrous oxide emissions, and NO 3 ‐N leaching at seeding rates of 20–60 kg ha −1 .
Kula et al. (2026) studied this question.