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Fig. 3. Chlorophyll (SPAD) values for corn relative to SPAD values from a nonlimiting N strip and the 95% confidence limits for different dates in 2002 and 2004. The N treatments for corn were H = 199 kg ha–1, M = 138 kg ha–1, L = 69 kg ha–1, R = 69 kg ha–1 of N applied at V1 to V3 with another 69 kg ha–1 N side-dressed at midseason (V16), and Z = no N fertilizer. Dotted horizontal line is at the 0.95 sufficiency threshold value. The dashed vertical line is the time of the midseason N application to the R treatment.
