Episode 86 | Making Every Nutrient Count: Fall Fertilizer Decisions for Productivity, Profitability, and Water Quality

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The Illinois Nutrient Loss Reduction Podcast

The Illinois Nutrient Loss Reduction podcast explores efforts to reduce nutrients in Illinois waterways from agricultural runoff to municipal wastewater with host Todd Gleason and producers Rachel Curry, Nicole Haverback and Luke Zwilling with University of Illinois Extension.

University of Illinois Extension soil fertility specialist John Jones advises farmers to delay fall nitrogen applications until soil temperatures at a four-inch depth fall to 50 degrees Fahrenheit and continue cooling. To further prevent nitrogen loss through leaching, he recommends using nitrification inhibitors to delay the microbial conversion of ammonium to vulnerable nitrate. While fall applications are common, there is evidence spring anhydrous ammonia applications require 16 to 20 fewer pounds of nitrogen per acre to achieve similar yields. For phosphorus and potassium, producers should rely on recent soil tests to avoid unnecessary applications in high-testing areas, keeping in mind that dry fall conditions can artificially lower potassium and pH readings. Finally, Jones advocates using the online Nitrogen Rate Calculator to determine application rates that maximize economic profit per acre rather than absolute maximum yield, ensuring that the cost of additional fertilizer does not outpace the value of the resulting crop. John Jones, Soil Scientist, Extension Soil Fertility University of Illinois