Jim Fawcett, Extension Field Agronomist, Southeast
The skyrocketing cost of nitrogen fertilizer as well as the nitrogen losses observed in 2008 due to the wet weather has many crop producers wondering about proper nitrogen fertilizer practices in the future. Nitrogen fertilizer losses result in lower corn yields as well as environmental concerns. Losses in corn yields in Iowa due to nitrogen losses in 2008 have been estimated at nearly a billion dollars.
The Corn Soybean Initiative partner, Linn Cooperative, and ISU conducted on-farm research and demonstration plots in the fall of 2007 and spring of 2008 to highlight different sources, timings, and rates of nitrogen fertilizer, as well as the use of nitrification inhibitors and urease inhibitors. Late spring soil nitrate and end of season stalk tests were conducted on the plots. A plot tour was conducted in August, and results of the trial were shared with other agronomists around the state. The information was highlighted at several “Making Fertilizer Decisions in Uncertain Times” presentations in eastern Iowa, as well as statewide in the Crop Advantage series.
The excess rains in the spring of 2008 resulted in large losses of nitrogen in farm fields and in the plots. This resulted in very large differences in corn yields based on the timing and rate of nitrogen application, resulting in a unique teaching moment on the benefits of waiting until spring to apply nitrogen. About 75 growers that attended the plot tour could see for themselves the benefits of waiting until spring or later to apply nitrogen or to use a nitrification inhibitor in the fall to reduce losses. Hundreds of others taught at the Crop Advantage series and other winter educational sessions could use the information to make decisions for the 2009 growing season.
100 Corn and Soybean Production and Protection
Page last updated:
April 14, 2009
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