CANOLA QUIZ – Nitrogen top-up

An in-season top-up of nitrogen fertilizer can make sense for a few reasons. For example, if growers cut back on rates with the dry start to the season, recent rains may have increased crop yield potential and its need for nitrogen. If the crop won't have enough, a top-up can make good economic sense.

1. On the 4R topic of Right Source, the Canola Encyclopedia says that if using a liquid fertilizer, apply _____________ to reduce absorption of liquid into the plant, which will increase the amount of leaf burn.

A fine mist

On a warm, dry day

When leaves are moist

With low rates of water

2. On the topic of Right Time, the Canola Encyclopedia says: "Ideally, a nitrogen top dress should occur _______________." (Fill in the blank.)

Before plants start to show deficiency symptoms

After herbicide spraying when the sprayer is available

Before the four- to six-leaf stage of the crop

Before flowering

3. For Right Rate, the Canola Encyclopedia says, "Growers may need to top dress up to ____ pounds per acre of actual nitrogen to visually notice an improvement, but yield differences for rates lower than that may show up at harvest." (Fill in the blank.)

4. For Right Place, the Canola Encyclopedia says broadcast spreading of urea or surface dribble banding of UAN are the most common and fastest methods, but these methods can also result in the highest losses if rain doesn’t follow soon after the application. The Encyclopedia notes that one of these options (urea or UAN) tends to be better than than the other for losses. Which one tends to have lower losses when broadcast?

UAN

urea

5. A detailed Canola Watch article on top dress tips lists a few factors that can increase nitrogen losses when nitrogen fertilizer is applied in-crop. Moisture is a major factor. Which moisture factor below would likely cause the highest amount of loss for a surface application?

Soil surface is bone dry

One tenth of rain follows application

Half inch of rain follows application

Air has low humidity