I wrote an ICM News article February 21, 2013, that provided a summary of fall soil profile nitrate sampling results following the 2012 corn harvest. As I cautioned in that and other articles, the amount of nitrate-N that might remain for a 2013 corn crop depends on springtime rainfall. Unfortunately, much of Iowa has received considerable precipitation since soils thawed, especially the eastern two-thirds of Iowa. The two maps of the Midwest region show the total precipitation and deviation from normal since March 7, 2013. Tile lines are flowing again, and nitrate in the profile will move with percolating water. Not all of the precipitation entered the soil, but the amounts received and comments from ISU Extension and Outreach field agronomists who have sampled soil profiles this spring for moisture content suggest the soil profiles in most of the state have been recharged. Therefore, we have lost the opportunity to use much of the profile nitrate carried over from last year. Also, this spring’s precipitation after the dry fall reminds us why profile sampling for nitrate is not a routine practice in much of the Corn Belt.
Iowa State University
Sawyer, John E., "Wet Conditions and Change in Soil Profile Nitrate" (2013). Integrated Crop Management News. 74.
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