S-NUTRITION OF YELLOWED BEECH AND SPRUCE IN THE SOUTHERN BLACK-FOREST

In spring of 1988, a European beech and a Norway spruce stand in the southern Black Forest were fertilized with MgSO4 to alleviate extreme Magnesium deficiency diagnosed by foliar and soil analyses. In addition to a fast and remarkable improvement of the Mg-nutrition and vitality of the fertilized trees at the end of the first and fifth growing season after fertilizer application, the SO4-S content as well as the S(org)-fraction had increased particularly in the leaves of the fertilized beech trees compared to the controls. When comparing the S(org):N ratios of fertilized and control trees it became evident that a considerable part of the absorbed sulphate had been metabolized. Foliar analysis data of 1992 indicate S-deficiency in the unfertilize, beech trees. It is concluded that the S-nutrition of both spruce and beech can be insufficient in areas with low S-deposition such as the southern Black Forest.