Effect of delayed nitrogen fertilization on corn grain yields

Scope and method of study. Delaying sidedress nitrogen (N) fertilizer application until later in the growing season has potential for increasing nitrogen use efficiency (NUE). Delaying N fertilization would also help to determine the amount of fertilizer N needed to be applied to achieve maximum grain yields based on the crops yield potential. This two-year study was conducted in 2005 and 2006 to determine the optimum nitrogen management strategy for corn by evaluating several combinations of preplant and sidedress N fertilizer applications at various growth stages.; Findings and conclusions. Higher corn grain yields and NUE's were achieved with preplant N applications followed by mid-season sidedress fertilization at V6-V10 growth stages. Grain yields were decreased when no preplant N was applied and sidedress N fertilization was delayed until the VT growth stage. Delaying N fertilizer until mid-season supplies N at the time when the crops need for N and N uptake are at maximum, and thus facilitates more efficient N fertilizer use. Results of this study suggest that preplant N followed by mid-season sidedress N application at or before the V10 growth stage is recommended for corn.