%0 Research Notes %T Pulp biosludge and coal ash as nutrient sources for silver birch seedlings %A Veijalainen, Heikki %A Silfverberg, Klaus %A Hytönen, Jyrki %D 1993 %J Suo - Mires and peat %V 44 %N 3 %U http://suo.fi/article/9730 %X Biosludge from a biological waste-water treatment plant was tested in a greenhouse experiment on three substrates at 7 levels (0-240 m3/ha). The growth of birch seedlings was best on nitrogen poor substrate collected from a Vaccinium vitis-idaea (VT) forest site. NPK-fertilization was superior to sludge treatments on poor peat substrate. Biosludge increased the foliar nitrogen content on all three soils. Nutritional value of coal ash was tested at 17 levels (0.4-160 t/ha) on mineral soil from an afforested field. Low application levels of coal ash (400-1600 kg/ha) increased the growth of the birch seedlings more than other applications. However, even extremely high coal ash amounts (up to 160 t/ha) were not lethal for birch seedlings. Coal ash increased foliar boron contents two to three fold and with applications higher than 20 t/ha increase was five to seven fold. Birches planted in 1978 on a coal ash landfilling area showed good survival and growth, despite toxic boron contents and visual disturbances in the leaves. Key words: Boron toxicity, fertilization, peat substrate, recycling