Spodosol variability and assessment of response to acidic deposition

Variability in forest soils makes it difficult to observe short-term changes in chemical properties under field conditions. A buried soil-bag technique was developed to examine the chemical response of a Maine forest soil to loadings of strong acids (HNO₃ and H₂SO₄). Acids were added by irrigation on 18 hardwood plots, 15 by 15 m, American beech (Fagus grandifolia Ehrh.) dominating. Treatments, with three replicates each, were control, low S, high S, low N, high N, and N plus S. Soils were typical northeastern Spodosols, with acidic forest floors (pH 3.6) and upper mineral soils (pH 3.4-4.0). The buried soil-bag technique detected small alterations in forest soil chemistry under field conditions, with minimal disturbance to study plots.