By Stephen K. Barnhart, Department of Agronomy
High levels of accumulated nitrate nitrogen have been found in drought-stressed corn plants in many parts of Iowa this summer. Where harvest of grain is impractical, and where corn silage is a logical harvested feed option, some fields are being chopped and ensiled. Many producers whose corn crop is too dry for proper ensiling intend to either graze the dried, standing corn crop or to bale and store them as dry stalks for winter feed or bedding. The ensiling process can reduce the nitrate concentration, but our best assumption, at the present time, is that the nitrate concentration will remain high in harvested, dry stalks, but will gradually diminish from stalks in the field as rainfall leaches the stalks over the next few weeks or months.
Based on these assumptions, Iowa State University Extension beef and dairy specialists will continue to monitor the nitrate concentration in these various crop materials over the next few months. Producers are encouraged to check with their regional extension beef and dairy specialists for the most current feeding recommendations.
An added caution: Don't be too hasty in baling corn stalks as dry stalk bales. Stalks baled too wet — greater than about 20 percent moisture content - will generate heat and reduce the already low digestibility of this material. Don't stack large round or large rectangular bales immediately. Allow any initial heat in the bales to dissipate before stacking. If heating goes unchecked, spontaneous combustion and fire can result in large stacks of heating bales.
Stephen K. Barnhart is a professor of agronomy with extension, teaching, and research responsibilities in forage production and management. Barnhart can be contacted at (515) 294-7835 or by email sbarnhar@iastate.edu.
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