Impacts of Nitrogen Fertilizer Application Timing and Rate on Sweet Corn Production Under Subtropical Environmental Conditions

Sweet corn (Zea mays convar. saccharata var. rugosa) is an important crop in the United States (US), particularly in the southeastern region. While effective nitrogen (N) management is essential for optimizing yields, the sandy soils and variable precipitation in this region impact N uptake. This study evaluates the effects of several N rates (ranging from 224 to 336 kg ha−1) and N fertilizer application timing (N fertilizer applied at emergence and side-dress stages) on sweet corn growth and yield under the subtropical environmental conditions of the southeastern US. Field experiments were conducted over three years in the states of Georgia (2020) and Alabama (2021 and 2022). In general, the weather conditions of each season had a direct impact on sweet corn growth, development, and yield parameters. Among all locations, the season in Alabama (2022) allowed for the highest yields (17,380 kg ha−1), which could be attributed to favorable weather conditions that required moderate nitrogen application rates (224–280 kg ha⁻1). Contrarily, the weather conditions of Alabama in 2021 and Georgia in 2020 impacted soil N availability, consequently leading to negative effects on sweet corn growth. Overall, N fertilizer management strategies are indicated to be region- and season-specific in order to enhance sweet corn production while protecting the environment from excessive N losses. Further research is still required to refine these strategies and improve predictive models for diverse climatic conditions.