At both sampling depths, differences in pH among ecoregions tended to differ (P<0.05) onlywhen the irrigated sites of the MG were included in the analysis. Their inclusion increased thepH of the MG relative to other ecoregions (data not shown). Removal of those sites from theanalysis eliminated this difference, rendering the effect of ecoregion non-significant. Even withthe removal of the irrigated sites in the MG, pH in this ecoregion was somewhat higher relativeto other ecoregions, likely owing to lower annual precipitation (Table 2) resulting in lessleaching of carbonates from the surface soil layer, and a shallower soil profile (i.e., closerproximity to calcareous bedrock materials). Ecoregion × year was not significant for pH, as
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