Evaluation of Plant Analysis and Chlorophyll Meter Readings for Corn Nitrogen Management Using the Boundary-Line Approach.

Plant analysis and portable chlorophyll meters are some of the available tools producers have to assess corn nitrogen status in-season, especially under conditions of N stress. The objective of this study was to determine if whole plant analysis at early corn growth stages and chlorophyll meter readings at silking could be used to predict no-till corn yield potential under N stress using the boundary-line approach.  The boundary-line approach is an alternative to traditional regression techniques. The boundary-line represents the yield potential at a given level of nitrogen stress. Field research was conducted in 2010-2011 at fourteen sites in Eastern Kansas and 540 data points were generated for this analysis. Both early season (V5-V8) N concentrations in whole plants and chlorophyll meter readings at silking provided evidence that this boundary-line approach can be used to predict the yield potential at various levels of N stress in Eastern Kansas. A larger data set over a broader geographic region is needed to assess the potential usefulness of these tools and analysis to predict yield potential when N is the factor limiting yield.