With the large rainfall events across many parts of Manitoba recently, some farmers are noticing yellowing in their crops and wondering if they should top up their fields with some more nitrogen fertilizer. Unfortunately, there are no easy rules to follow or large experimental datasets to refer to for making this type of decision.
The attached article by Dr. Don Flaten, University of Manitoba, and John Heard, Manitoba Agriculture, outlines some principles if considering midseason application of nitrogen fertilizer.
And remember….the first issue to consider is whether the crop yellowing is from N deficiency or simply flooding stress due to excess water. Applying N fertilizer onto crops that are suffering primarily from flooding stress could be a poor investment.
Submitted by: John Heard, Crop Nutrition Specialist, Manitoba Agriculture
Visit Manitoba Agriculture website at http://www.gov.mb.ca/agriculture/crops/soil-fertility/ for more information on soil fertility.