Many canola regions have good conditions right now,growers who have better than usual canola growing conditions may consider a topdressing nitrogen if they didn’t apply enough fertilizer to meet revised yield expectations. Growers in western Saskatchewan, eastern Alberta and the Peace regions should consider a dribble band of liquid nitrogen or broadcast ammonium sulphate before the 4-6 leaf stage. After that stage, the payoff from a nitrogen top up is reduced.
Growers may still see a benefit from the sulphur-nitrogen combination in ammonium sulphate. In western Saskatchewan, Clint Jurke, CCC agronomy specialist has noticed sulphur deficiency in some canola this year, particularly in well-drained land where rains washed sulphur lower in the soil profile, below the depth shallow roots can access.
Field conditions critical: If canola is growing in excessively wet conditions, yellowing and purpling may be the result of moisture stress .But if soil conditions are good, discolouration may be the result of nutrient deficiency.
Factors to consider: Nitrogen topdressing can extend the vegetative period and delay crop maturity. Consider the calendar date and the fall frost risk when making a nitrogen top up decision.
As canola plants grow their roots will start to access sulphur reserves that moisture carried lower into the soil profile. Growers who have been applying recommended rates of sulphur may find that topdress may have a lower economic return than those who have cut sulphur rates.