Acid-base characteristics of soils in the Adirondack Mountains, New York

It is believed that atmospheric deposition of S and N in the Adirondack Mountains of New York has depleted soil-base cation pools, reduced soil base saturation (BS), and contributed to enhanced acidification of soils and surface waters. However, data to determine changes in soil characteristics are generally lacking. It is expected that soil acid-base status will improve as acidic deposition declines in response to atmospheric emissions controls. We studied edaphic characteristics at 199 locations within 44 statistically selected Adirondack lake-watersheds, plus 26 additional watersheds that are included in long-term lakewater monitoring programs. The statistically selected watersheds were chosen to be representative of Adirondack watersheds containing lakes larger than 1 ha and deeper than 1 m that have lakewater acid neutralizing capacity (ANC) less than or equal to 200 μmol_c L^-1. Results of soil analyses were extrapolated to the watersheds of 1320 low ANC lakes. In general, the concentrations of exchangeable base cations, base saturation, and soil pH were low. More than 75% of the target lakes received drainage from watersheds having average B horizon exchangeable Ca concentrations < 0.52 cmol_c kg^-1, base saturation < 10.3%, and pH (H₂O) < 4.5. Variations in the effective cation exchange capacity in both O and B horizons were closely correlated with soil organic matter content. These data provide a baseline against which to compare future changes in regional soil chemistry, and provide input data for aquatic and terrestrial effects models intended to project future changes in surface water chemistry, biological conditions, and forest health.