Fig. 4. Gravimetric soil moisture in the amended and nonamended soil treatments (a) in the first year soil moisture was measured (1995), (b) at the end of Phase 1 (1998), and (c) 6 yr into Phase 2 (2004) of the Maine Potato Ecosystem Project (n = 8). Error bars correspond to 1 SE. Significant differences between the treatments in any given year are indicated with * p < 0.05, ** p < 0.01, and *** p < 0.001.