Evidence from chemical changes in incubated soils for effects of sea salt deposition on Scottish upland soils

Evidence in the literature supporting the hypothesis that inputs of sea salts from the atmosphere increase soil pH and exchangeable Na+ and Mg2+ concentrations in soils in which the release of base cations by mineral weathering is slow is briefly reviewed. It is postulated that if a sea salt effect indeed occurs, long-term incubation of such soils in a field moist state should result in a decline in soil pH and in the relative importance of exchangeable Na+ and Mg2+ on the cation exchange sites. The postulate is confirmed by examining changes in pH and base cation ratios in soils incubated over 3 months at 4 degrees C or at room temperature or for 20 months at ambient outdoor temperatures in Aberdeen. The results obtained during the shorter incubation period support the hypothesis. However, the soil changes observed after 20 months of incubation are more variable, and interpretation is complicated by the high degree of oxidation of organic C observed.