Detoxification and amelioration of heavy-metal contaminated forest soils by means of liming and fertilisation

Four experiments were established in 1992 in Scots pine stands (Pinus sylve stris L.) on relatively infertile sites at distances of 0.5, 2, 4 and 8 km to the south-east of the Cu-Ni smelter at Harjavalta, south-west Finland, i n order to investigate the effects of liming, correction fertiliser and sit e-specific fertiliser treatments on heavy metal (Cu, Ni) and macronutrient (Ca, Mg, K) availability in the organic layer. The organic layer samples we re analysed for total, plant-available (BaCl2 + EDTA) and water-extractable Ca, Mg, K, Cu and Ni. A high proportion of the Cu and Ni at 0.5 km was in a non-toxic, immobilised form. Liming had only a relatively small reducing effect on free and exchangeable Cu and Ni concentrations at 0.5 km. The lac k of pH increase following liming may be due to the precipitation of Fe, pr esent in very high concentrations close to the smelter, as Fe(OH)(3), resul ting in the loss of neutralising bicarbonate and hydroxyl ions, but the rel ease of Ca and Mg. Liming strongly increased Ca and Mg availability. The co rrection fertiliser had no effect on Ca or K availability at any of the sit es. (C) 1999 Elsevier Science Ltd. All rights reserved.