Maximize the benefits of top-dress nitrogen

A good rain swept through much of Alberta in early June, dropping 50 – 140 mm (2 to 5.5 inch) of rain in various regions. The rain has provided relief to the dry conditions and optimism for the upcoming growing season. If your target yield has been bumped up because of the rain, top-dressing nitrogen is a common practice to match the nutrient demand with the new target yield.  

A few considerations play into making the most of top-dressed nitrogen. In short, the best management practices include: 

Timing/growth stage

Nitrogen applied before the end of tillering (GS 29) is most effective in increasing yield potential. Starting from stem elongation stage, top-dressed nitrogen can only maintain yield potential, or go towards grain protein. 

Minimize N loss

Though often foliar-applied, plants absorb most of the N through their roots. Urea or fertilizer products containing urea broadcast on soil surface are prone to N loss through volatilization. Dribble banding, fertigation or applying within 2 days before a rain event of ½ inch or more can reduce N losses and maximize plant absorption. 

Avoid fertilizer burn 

UAN can cause leaf burn when applied at higher rates or during hot, dry conditions. To minimize the risk of leaf burn, use moderate rates, dilute UAN with water and apply later in the day to avoid high temperature and sunlight conditions.  

Refer to Managing In-crop nitrogen in cereals for more information.