BONDUEL, Wis. — Looking to evaluate your nitrogen fertilizer program?  Take a closer at your corn stalks. End-of-season corn stalk testing helps give some insight into how well nitrogen fertilizer was utilized by the corn plant. These results won’t change your yield this fall, but it is more data to use for future management decisions.
“Corn expresses symptoms when nitrogen is deficient,” said Steve Peterson, AgSource Laboratories vice president, laboratory services. “But there isn’t a visible sign for over fertilizing. Corn stalk testing can alert you to excess nitrogen levels and help plan for next year.”
A relationship between stalk nitrate concentrations and relative yields is derived from trials. Studies at Purdue University and Iowa State University show that the nitrogen status of a corn crop can be assessed by measuring nitrate concentrations in the lower portion of cornstalks at the end of the growing season.
Corn plants with inadequate available nitrogen remove N from lower cornstalks and leaves during the grain filling period. Corn plants with excess N accumulate nitrate in their lower stalks at the end of the season. Corn stalk N concentrations can be divided into categories for interpretation, ranging from Low/Deficient to High/Excess.  
Accurate analysis is dependent on correct sampling procedures. Sample collection, preparation and shipping can influence the results. Instructions on how to take a representative sample can be found here.


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