To meet N level needs while avoiding weather-related pitfalls, growers can spread risk by applying N at multiple times. Nitrogen may be applied in the fall, early spring (preplant), at planting and in-season (sidedress).

"The ideal circumstances are to do a split application," Shanahan says. This time of year – in-season – N applications allow for adjustments to planned N supply based on weather variations.

If wet spring conditions result in N losses, sidedress rates can be increased. If warm temperatures and moderate rainfall results in high N mineralization and an N-sufficient crop, sidedress rates can be reduced. (Determining these needs can be done using the evaluation tools noted above.)

In-season N applications can supply N to the crop near the time of maximum plant uptake. However, if wet conditions develop, sidedress applications may be delayed beyond the optimum application date. Very dry conditions can result in a delay in availability of sidedressed N to the plant.

Because of the risks associated with in-season N application, the practice should be managed carefully. Soil fertility specialists often recommend only one-third of total crop supply be targeted for sidedress application. In addition, growers should be prepared to apply sidedress N as quickly as possible when the window of opportunity appears. Finally, a backup plan should be in place for in-season application to help avert significant nitrogen deficiency and yield loss in case of weather issues.

"To make the most of N applications, growers need to evaluate the type of equipment and N sources available," Shanahan says. "They also need to assess the weather and adjust based on conditions to ensure an N strategy that delivers."

To help evaluate your N needs and choices, consult your area Pioneer agronomist or university Extension resources for assistance, or visit the agronomy section of