24 Like Us on Facebook: BetterFarmingON Better Farming | June/July 2024 More isn’t always better when it comes to applying nitrogen fertilizer – agronomically or financially – certainly not in the face of federal goals to slash nitrous oxide emissions. “In some cases, a little less N may be more,” says Colin Elgie, OMAFRA soil fertility specialist. He explains nitrogen (N) fertilizer plays a critical role in farmers’ cropping systems, particularly in grain crop production. “When used at the proper rate, nitrogen fertilizers promote increased growth and yield, and improved profitability,” Elgie says. “However, overapplication of N fertilizers can and does occur, as the relationship between N and yield is not simply a straight line, where more is always better.” Different factors illustrate why adding more N to crops may not necessarily be in a farmer’s best interests. Agronomic optimization Elgie says grain crops in Ontario respond well to N fertilizer, but that the relationship has its limits, as increasing rates of N applied to a crop will eventually reach a yield plateau. “At this rate, additional N fertilizer will not increase yield, and if applied at exceptionally high rates, can decrease yield,” he says. Issues such as delayed maturity and stalk lodging can reduce quality and harvestable yield. The effects are easily seen in winter wheat, for which high rates of N, coupled with early summer storms, can lead to flattened fields prior to harvest. Impacts are also evident in corn yields. Alfons Weersink, an agricultural economist at the University of Guelph, says in terms of corn’s response to N, yields increase at a decreasing rate until a maximum yield is hit, and then it essentially plateaus. ‘THE RELATIONSHIP BETWEEN N AND YIELD IS NOT SIMPLY A STRAIGHT LINE.’ OVERAPPLYING NITROGEN: WHEN MORE ISN’T BETTER By RICHARD KAMCHEN Appying Nitrogen Emily Croft photo
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