Ontario soil nitrogen supply looking good as corn side-dress timing nears

OMAFRA corn lead Ben Rosser.

Ontario corn growers appear to be sitting on strong yield potential as the the crop shakes off the effects of cool late May weather.

Early planting and some timely, albeit limited, rains across the province have propelled the crop forward. With herbicide application expected to wrap up this week, growers will then turn their attention to the nutrient needs of the crop, and whether side-dress nitrogen is required.

Based on the results of the Ontario Ministry of Agriculture, Food and Rural Affairs’s annual Pre Side-dress Nitrogen Test (PSNT) survey, soil supplies of the key nutrient appear to be in good shape. Ben Rosser, OMAFRA’s corn lead, reports that the PSNT survey indicates the average PSNT value for 2021 was 13 ppm, similar to the long-term average of 12 ppm. The results are based on soil samples collected from 93 sites across Ontario from May 31st to June 2nd, 2021.

Overall soil nitrogen supply (mineralization and losses) can be influenced by weather (soil temperature and moisture) each spring. At Tuesday’s virtual Exeter/Mount Forest agribusiness meeting, Rosser said that the absence of saturating rains has produced minimal loss. He noted that survey results are very similar to 2018 and 2020 — both fairly warm and dry springs, with some cool periods, similar to 2021 conditions.

For growers, the next question is to determine their corn crop’s nitrogen needs. Rosser noted that the PSNT survey results are a general indication of soil nitrogen status across the province and it’s important for growers to sample their own fields before making fertility management decisions.

At the meeting, Pioneer Hybrid sales representative Russ Barker shared some thoughts on what growers should be factoring into their decision. He noted that the absence of moisture means most of the nitrogen applied prior to planting should still be available to the crop. For growers who want to side-dress, the question now becomes how much do you apply. Some may want to feed the crop to drive yield while others may be leery of high-priced UAN 28%. That price will need to be factored into the the equation, says Barker, but with new crop corn prices at $7 per bushel many growers may consider it a good investment.

Check out the full PSNT survey report at Field Crop News.

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