Long-term Forest Ecosystem Research LWF

(44) Soil solution

Soil solution, i.e., the water in the pore space of soils, contains dissolved mineral nutrients that are essential for the growth and vitality of plants and soil organisms.

Atmospheric acid deposition can influence the chemical composition of the leachate and thus of the soil solution. As a result, soil acidification may accelerate, which not only leads to nutrient losses but can also increase the concentration of acidic cations (e.g., aluminum), which have a toxic effect on roots and can inhibit root growth.

By continuously analysing the chemical composition of soil solutions, we monitor the acidification processes and the nutrient balance of the soil in the rhizosphere.

Every two weeks the soil solution is aspirated with lysimeters at four soil depths: directly under the litter layer, and in 15 cm, 50 cm, 80 cm. The samples are mixed in the laboratory, filtered and chemically analyzed.

Based on our soil solution monitoring, we were able to confirm that as a result of the reduced atmospheric sulphur deposition, the concentrations of sulphate in the topsoil have decreased on most LWF sites (Fig. 3).