The effects of forest liming on fertilization on fine-root growth

Results are reported from the investigations of fine-root development in Norway spruce and Scots pine stands in South and Central Sweden, subjected to different liming and fertilization regimes. The growth responses of the fine roots to varying mineral nutrient regimes seem to be dependent on the tree species, the age of the tree population and soil conditions. Nitrogen fertilization in some of the investigated stands had negative effects on the development of fine roots, resulting in a reduction in the amount of fine roots to about 50% of that in the control. However, negative effects were not consistent in all stands, positive growth responses were also obtained. In these stands, the amount of fine roots was increased by 2 to 3 times. Liming in combination with fertilization resulted in a strong decrease in the amount of fine roots to about 30% of that in the control in some of the investigated stands. Liming in high doses is expected to produce a persistent increase in pH (H₂O) and base saturation in the soil. However, results from the present study suggest that liming may have a negative effect on the development of tree fine roots, particularly in areas with a high N deposition. The application of crushed dolomite had less negative effects on fine root development than crushed calcitric lime and different types of residue products, such as wood and peat ashes.