Effect of Delayed Nitrogen Fertilization on Corn Grain Yields

Abstract

Delaying nitrogen (N) fertilization until mid-season may increase nitrogen use efficiency (NUE), and can assist in determination of fertilizer N needed to achieve maximum grain yields based on the crop's yield potential. Previous research showed that corn yield potential can be accurately estimated mid-season using optical sensor measurements at V8. This study was conducted to determine if N fertilization can be delayed until mid-season without decreasing yields. Several combinations of preplant and sidedress N fertilizer applications at various growth stages were evaluated. Higher corn grain yields and NUE's were achieved with preplant N followed by mid-season sidedress at V6-V10 growth stages. Grain yields were decreased when no preplant N was applied and sidedress N was delayed until tasseling. Results suggest that preplant N followed by mid-season sidedress N application at or before V10 is recommended for corn giving a window of opportunity for N fertilization of 15 to 20 days.