The impact of acid rain on potassium and sodium status in typical soils ofthe Wielkopolski National Park (Poland)

A previous investigation of the chemical characteristics of precipitation i n the Wielkopolski National Park has shown its high acidity, which sometime s drops below pH 3.0. This paper deals with the leaching of potassium and s odium ions by acid rain from typical soils of the study area. Laboratory ex periments were conducted on undisturbed soil cores (15 cm in diameter, 50 c m high) with acid solutions of pH 3.0, pH 2.0 and with water of pH 5.6 (con trol). The sprinkling lasted 30 days simulating a rainfall of 400 mm. The e luates were analysed daily. Soil properties and forms of potassium and sodi um were determined before and after treatment. The investigations show that quite significant amounts of K+ and Na+ can be leached from the soil: in t he very acid treatment (pH 2.0) about 4 mg K+ and 3 mg Na+ per kg of soil. The leaching of these elements was smaller in the pH 3.0 and 5.6 treatments . Differences in the dynamics of the process are shown in the leaching curv es. In the case of potassium their shapes are smooth when pH is 5.6 and 3.0 , while at pH 2.0 the curves rise sharply. The leaching curves in the case of sodium do not show sharp peaks, which means that the leaching is slow an d equalised.