Soil response to s and n treatments in a Northern New England low elevation coniferous forest

Abstract

A field experiment was designed to evaluate the effects of differing forms of acidifying S and N compounds on the chemistry of soils and soil solutions in a low elevation coniferous forest in northern New England. Treatments consisted of O, 1500, 3000, and 6000 eq of SO42− or NO3− ha−1 for the 1987 growing season applied biweekly as H2SO4 or HNO3, or in a single application as dry] (NH4)2SO4. Acidifying treatments resulted in a significant increase in soil solution SO42− (1.2 to 2.6) or NO3− (12 to 80) in the upper B horizon. Excess strong acid anion leaching was associated with an accelerated loss of base cations, particularly MG2+ As solutions passed through the upper 25 cm of the soil profile, mean SO42− concentrations decreased by 5 to 50% of the initial values, indicating that much of the applied SO42− was immobilized in the upper portion of the pedon. Elevated concentrations of adsorbed and water-soluble SO42− indicate that abiotic adsorption of SO42− by soils is the dominant mechanism for the initial attenuation of SO42− concentrations in these solutions. Other soil properties showed only small or no change due to treatments over the single growing season of this study. These results indicate that H2SO4, HNO3, and (NH4)2SO4 can all effectively increase strong acid anion concentrations in the soil-soil solution system.