Fig. 1. (A) Geographic location of the experimental site. (B) Layout of the experimental site shows location of lysimeters. Strips 1 and 3, tilled N fertilized corn from 1988 to 1997. Strip 2, tilled N fertilized corn from 1988 to 1990, alfalfa from 1991 to 1993, and post-alfalfa tilled corn in 1994. X indicates the plots that have zero-tension lysimeters installed (adapted from Zhu, 2002).