Abstract: To clarify acid buffering capacity of different soil types and the main influencing factors, we collected 0-20 cm top soils from eight types of representative soils in eastern China (black soils, aeolian soils, brown earths, chernozems, purplish soils, red earths, yellow earths, and laterite), and measured acid buffering capacity and the related physicochemical properties. In areas under agricultural cultivation, soils were collected simultaneously from adjacent natural vegetation (woodland or grassland) and farmland. The results showed that acid buffering capacity of soils in the northern part of eastern China (44.8 mmol·kg^-1) was significantly higher than that of the soils in the southern part (15.8 mmol·kg^-1), which can be ascribed to the greatly higher concentrations of carbonate, exchangeable base cations, and organic matter in the northern soils. Differences in soil minerals, temperature, and precipitation between northern and southern parts of eastern China were responsible for the differences in soil acid buffering capacity and related physicochemical properties. The acid buffering capacity of farmland soils (36.6 mmol·kg^-1) was significantly higher than that of forest soils (25.0 mmol·kg^-1), which might be due to higher carbonate concentration and base saturation in farmland soils. Fertilization in farmland was responsible for the above differences. Soil acid buffering capacity was positively correlated with the concentrations of carbonate, exchangeable calcium, and organic matter (P<0.01), positively correlated with base saturation, exchangeable magnesium concentration, and cation exchangeable capacity (P<0.05), but negatively correlated with exchangeable acid concentration (P<0.05). Therefore, concentrations of soil carbonate, exchangeable calcium and organic matter are the main factors influencing soil acid buffering capacity in eastern China.

Key words: carbonate, exchangeable calcium, organic matter, regional difference, land use type.