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Basis for Testing


End of season stalk testing was developed to evaluate how well nitrogen fertilizer was utilized by the corn plant. This allows the producer to distinguish between over fertilization and fertilizing to maximize profits.


A relationship between stalk nitrate concentrations and relative yields was developed from trials having rates of N fertilizer applied ranging from 0 to 300 lb. N/acre.

Corn plants with inadequate available nitrogen remove N from lower cornstalks and leaves during the grain filling period.

Corn plants with excess N for maximum yields accumulate nitrate in their lower stalks at the end of the season.

This relationship indicates that stalk N concentration can be divided into four categories for interpretation.

For laboratory specific information regarding plant tissue analysis, procedures, guidelines, test packages/supplies or analysis kits, please contact one of our laboratories nearest you listed below:  

Laboratory Locations:

AgSource Laboratories - Bonduel, WI715-758-2178 bonduel@agsource.com 
AgSource Laboratories - Ellsworth, IA 515-836-4444ellsworth@agsource.com 
AgSource Laboratories - Lincoln, NE 402-476-0300 lincoln@agsource.com 
AgSource Laboratories - Umatilla, OR541-922-4894 umatilla@agsource.com