Bilanzierung von Stofffluessen in magnesiumgeduengten Fichtenoekosystemen im Schwarzwald (Projekt ARINUS)

1992

S. 88-101

27 Lit. Ang.

Unselbständiges Werk

200060416

Within the ARINUS Project treatment of a whole watershed with kieserite (750kg/ha MgSO4H2O) based on the Mg cycling in the control watershed was performed. The ARINUS experimental site Schluchsee located in the higher elevations of the Black Forest (SW Germany) is characterized by severe Mg deficiency and 'unstable N reserves in the soil. With the fertilizer, 130kg/ha Mg were introduced into the system. Fertilization resulted in increased levels of Mg and S in the needles. Despite high inorganic Al concentrations and extremely low Ca/Al ratios in the soil solution, there was no evidence for 'Altoxicity . Fertilizer losses from the system 2 1/2 years (3 growing seasons) after the treatment have been modest, surface water has hardly been affected. More than 70% of the applied Mg has remained in the ecosystem, primarily in the intensively rooted upper soil layer. Therefore, fertilization with readily soluble sulfate-based Mg fertilizers is recommended as an efficient and - in comparison to liming - less risky restoration measure on sites with a high potential for nitrification. To avoid critical Al concentrations in adjacent surface waters, salt fertilizers should not be applied to sites with high amounts of shallow subsurface flow.