Corn response to in-furrow fertilizer and fungicide across rye cover crop termination timings

Farmers looking to maximize soil conservation benefits of a rye cover crop (Secale cereale L.) (RCC) may choose to delay termination closer to corn (Zea mays L.) planting. However, delaying RCC termination may reduce corn yield due to nitrogen (N) immobilization and seedling disease. The objective of this trial was to evaluate corn growth and yield in response to in-furrow (IF) fertilizer and fungicide following a RCC and across different RCC termination timings. A field study was established at three locations in Kentucky in 2019 and 2020 to evaluate corn response to two RCC termination timings (21 d before corn planting [early terminated] and 1 d after corn planting [postplant terminated]) and three IF starter treatments (fertilizer, fungicide, and fertilizer + fungicide). A postplant-terminated RCC resulted in greater rye shoot biomass, early-season (Apr-May) soil moisture, and preplant soil inorganic N compared with an early-terminated RCC. Also, a postplant-terminated RCC reduced corn stand by an average of 31% at two of three locations and reduced corn yield by an average of 15.7% across locations. The inclusion of IF fertilizer, fungicide, or fertilizer + fungicide did not improve corn yield at any location, and no interaction between RCC termination timing and IF starter was observed. Overall, our results suggest IF fertilizer and/or fungicide does not ameliorate corn stand and yield reductions following a postplant-terminated RCC. In addition, farmers should look to terminate a RCC earlier (14-21 d before planting) to reduce potential corn stand and yield loss.