IN-SITU SOIL SOLUTION CHEMISTRY IN AN ACID FOREST SOIL AS INFLUENCED BY GROWING ROOTS OF NORWAY SPRUCE (PICEA-ABIES [L.] KARST)

A new approach for non-destructive monitoring of soil solution chemist ry in high spatial and temporal resolution for rhizosphere studies is presented. In a 5 x 10 mm grid, 30 micro suction cups (01mm) were inst alled in a rhizotron with Norway spruce (Picea abies [L.] Karst.) grow ing in low pH B-horizon soil. Roots grew through the grid, closely pas sing the suction cups. Soil solution composition before, during and af ter root passage was determined. For K+ and Mg2+ a significant decreas e of soil solution concentration near root tips and elongation zones w as observed, indicating a marked uptake of these elements. Mg2+ concen tration was also significantly lowered when the root system aged, sugg esting that this ion might also be taken up in older parts of the root system. No influence of growing roots was found on Na+-concentrations .