Abstract |
Much research within the past decade has focused on the effects of increased sulfur (S) deposition on surface waters. As inputs of S deposition as SO4(2-) build up in the soil over time, the concentration of SO4(2-) leaching from soils may also increase. Leachate SO4(2-) concentrations were greater for the high-S than for the low-S treatment for each soil type, resulting in greater cation leachate concentrations for soils that received the high-S treatment. Calcium was the primary base cation in both the Spodosol and Alfisol leachates. Declining concentrations of base cations and NH4(+) over the length of the study led to an increase in Al(3+) concentrations and decrease in pH for some of the Spodosol leachates. It is difficult to extrapolate their laboratory rates of change to the BBWM catchments because of differences between the experiment and field conditions. Soil temperature, the amount and rate of S application, and the total mass of soil exposed to treatment were hypothesized to be important factors affecting net S retention in Spodosols under field conditions. However, the authors feel that SO4(2-) adsorption under field conditions would still be the primary mechanism of S retention because of similarities between SO4(2-) concentrations in treatment solutions used for the present experiment and those in natural throughfall solutions. |