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Fig. 1. Monthly flow-weighted nitrate N concentration in subsurface tile drainage as affected by time of N application (time) and nitrapyrin (NP) for (a) corn grown in even years (1994, 1996, and 1998) and (b) corn grown in odd years (1995, 1997, and 1999) for six cycles of a corn–soybean rotation. All months shown had drainage exceeding 9 mm. Notations above each monthly data set indicate statistical significance at P = 0.01 (**), 0.05 (*), and 0.10 (
). Absence of a notation above a monthly data set indicates no significant difference between the flow-weighted nitrate N concentrations.
