Massive Nitrogen Loss From Midwestern Corn 2008-2010.

Rainfall during April through June was well above average across much of the midwest for 2008, 2009, and 2010. I acquired aerial photographs documenting nitrogen deficiency in corn across several states each year. Mississippi River nitrate concentrations were above normal in these years, indicating that leaching to tile drains or springs/seeps was an important loss mechanism. Preliminary calibrations between relative greenness (from aerial photos) and yield have been developed. These calibrations will be applied to additional photos to assess yield loss. Yield loss estimates will be used to roughly estimate nitrogen loss. I will present and discuss management options for reducing or responding to such losses, including yield responses to rescue N applications.