Response of a Scots pine (Pinus sylvestris) stand to application of phosphorus, potassium, magnesium and lime. 1. Soil data

In 1985-1988, a 25-yr-old Scots pine forest in Netherlands was limed and fertilized with P, K and Mg in a 24 factorial design and in an experiment with 5 liming levels, in order to alleviate potential nutrient deficiencies as a result of high N depositions (ca. 40 kg ha-1 yr-1). In this paper, effects of fertilization and liming on nutrients in forest floor and mineral soil are discussed as a basis for explanation of foliar nutrient concentrations and tree performance. Of all treatments, liming showed the widest array of effects, especially in forest floor: raised pH and lowered extractable Al in forest floor, and after 4 yr those in 0-50 cm mineral soil. These effects, except for that on forest floor pH, were stronger with increasing lime dosages. Liming showed transient effects on amounts of soil inorganic N (Ni). Until 1989, Ni in forest floor was lowered and that in mineral soil was raised by liming. This could be attributed to the formation of NO3, which is more mobile than NH4. Plots limed with 3 t lime/ha appeared to have higher Ni concentrations in the whole sampled profile than those limed with >3 t/ha or unlimed plots, the reason for which is unclear. Liming removed extractable K and Mg from forest floor probably by exchange against Ca. Residence time of added P and possibly Mg in forest floor was increased by liming, probably by solubility of added fertilizers. Added K was poorly retained in forest floor and probably quickly leached to soil layers deeper than 50 cm.