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Fig. 3. Linear regression of (a) total potato yield and (b) U.S. no. 1 potato yield on June through August rainfall for amended (filled triangle) and nonamended (open triangle) soil management treatments of the Maine Potato Ecosystem Project, 1992 to 2004. Individual data points are the mean of four replicates (n = 4). Probability values are from extra sums of squares (ESS) analysis comparing amended vs. nonamended soil regression lines (n = 52; 13 yr times four replicates).
