Topdressing Canola

In the haste to seed canola, fertilizer may have been omitted because of time constraints. Top-dressing canola is very much like top-dressing wheat. The fertilizer nitrogen and sulfur can still be applied while the crop is small. The best top-dressing method is with dry fertilizer. Ammonium sulfate (21-0-0-24) is the favored nitrogen and sulfur source. Ammonium sulfate can be blended with urea to make up the total N needs of the crop. The application should be made to dry plant tissue. Rain will be needed to incorporate the fertilizer. Application of urea without rain for over a week in hot, dry weather may result in significant N losses through volatility. Only 1/4-1/2" of rainfall is usually necessary to incorporate urea. Timing the fertilizer application within a few days of rain is helpful in increasing topdress efficiency. Application of foliar fertilizer is discouraged because of the potential for leaf burning.