| Abstract: | Fertilization with calcined magnesite and Mg-hydroxide for site amelioration in a heavily damaged Norway spruce ecosystem Fertilization experiments with calcined magnesite and Mg-hydroxide were carried out in a heavily damaged, 60-year old Norway spruce ecosystem at Hohe Matzen in the Fichtelgebirge/NE-Bavaria. The site is characterized by high atmospheric inputs with deposition rates of 1.25 kg H, 42 kg S, and 32 kg N per ha and year, and low pH-values of the soil (typic Dystrochrept derived from granite). The trees show severe symptoms of needle yellowing due to Mg-deficiency. Fertilization resulted in manyfold increased Mg-concentrations in soil solution down to 70 cm soil depth and a significant increase of pH down to 25 cm mineral soil depth. Nitrate concentrations were higher after fertilization, but decreased within 15–24 months below the control level. The higher solubility of the Mg-hydroxide resulted in an earlier and clearer pH-increase paralleled by a decrease of the NO3-concentrations. As a mean over the whole experimentation period no increased N-output from the soil was found after hydroxide application. Fertilization also increased the amount of exchangeable Mg down to 40 cm mineral soil depth. Application of Mg-hydroxide leads to higher Mg-contents in recent-year needles three vegetation periods after fertilization. The lower solubility of magnesite results in a half- to one-year delay in its effects on soil chemical parameters with no reaction of the needle contents within this period. |
