26 Story Idea? Email Paul.Nolan@Farms.com Better Farming | July/August 2024 ‘THE RELATIONSHIP BETWEEN N AND YIELD IS NOT SIMPLY A STRAIGHT LINE.’ OVERAPPLYING NITROGEN: WHEN MORE ISN’T BETTER By RICHARD KAMCHEN APPLYING NITROGEN More isn’t always better when it comes to applying nitrogen fertilizer – agronomically or financially – and certainly not in the face of federal goals to slash nitrous oxide emissions. “In some cases, a little less N may be more,” says soil fertility specialist Colin Elgie. He explains nitrogen (N) fertilizer plays a critical role in growers’ 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 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. Agricultural economist Alfons Weersink says in terms of corn’s reTracy Miller photo
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