Direct and residual effects of sulphur pollution on the acidity of a loamy soil

The aim of this investigation was to evaluate both the direct and residual effects of S pollution in the form of simulated acid rain (as dilute H2SO4, pH 2.8–3.5) on the chemical properties of a loamy soil. Five S treatments equivalent to different levels of S deposition (0, 62.5, 125, 250 and 500 kg S. ha−1 .yr−1) were considered. These treatments were superimposed on soils with added lime (CaCO3) according to lime requirements and soils without lime. The study showed a strong degradation of the soil as affected by excessive addition of S. It revealed that the process of soil degradation did not end once the inflow of S to the soil was stopped. After the input of S was cut off and the excess of S washed out, the pH of the studied soil continued to decline. There was also a substantial decrease in the saturation of the exchange complex with bases, mainly as a result of further losses of Ca and Mg from the soil. Both in the case of direct and residual effects of S addition, liming decreased the rate of soil degradation and, hence alleviated the negative effects of the phenomenon.